Effect of Primary PCI in asymptomatic STEMI patients presenting 12-48 hours of symptom onset, on myocardial viability assessed on SPECT - ‘EPITOME-99’

Effect of Primary PCI in asymptomatic STEMI patients presenting 12-48 hours of symptom onset, on myocardial viability assessed on SPECT - ‘EPITOME-99’ | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Effect of Primary PCI in asymptomatic STEMI patients presenting 12-48 hours of symptom onset, on myocardial viability assessed on SPECT - ‘EPITOME-99’ Manjunath Suresh Pandit, Sibasis Sahoo, Vishalkumar M Patel, Senthilraj Thangasami, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4163687/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background : Guidelines on revascularization of asymptomatic STEMI patients presenting 12-48 hours of symptom onset are limited, evidence contributing lack of symptoms to non-viable myocardium are scarce. We utilized TC-99mSestaMIBI scan to study the impact of primary PCI on myocardial viability by deriving myocardial salvage index (MSI) in asymptomatic STEMI patients presenting between 12-48 hours of symptom onset to PCI. Methods and results : We enrolled 141 patients with STEMI (12-48 hours), from January 2020 to December 2023, who then underwent TC-99mSestaMIBI scan, followed by revascularization of IRA with 138 patients completing the designed study with follow-up scan at 3 months. A substantial MSI of > 0.50 was achieved by 36 %, 8% and 5 % of patients from cohort A(12-24 hrs.), B(25-36 hrs.), and C(37-48 hrs.) respectively.Post Hoc analysis determined a comparable AAR of 34.47 %( ±11.70) throughout cohorts, however a greater reduction in FIS [Q=4.72 (p=.00309)]and MSI gain was noted among patients of cohort A alone [Q=4.18 (p=.01025)]. Regression analysis of MSI against PCI timing was negatively correlated (R= -0.41). Conclusion : Asymptomatic stable STEMI patients presenting 12-24 hours of symptom onset to PCI, benefited from primary PCI with lesser final infarct size and larger MSI. Despite a comparable AAR across cohorts, MSI fell sharply among patients undergoing primary PCI 24-48 hours of symptom onset with a larger final infarct size, warranting viability guided revascularization. Although primary PCI improved final LVEF and MSI in patients with ischemic heart failure, parameter gain alone was insufficient in endeavoring a positive clinical impact. ST segment elevation MI Percutaneous coronary intervention Myocardial salvage index TC-99m SestaMIBI scan Late presenting myocardial infarction Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 INTRODUCTION In patients with acute ST-segment elevation myocardial infarction (STEMI), the time interval between symptom onset and hospital arrival is one of the most consistent predictors of mortality 1 . Most deaths occur at the start of disease manifestation, and in the 40% to 65% of the cases, death occurs within the first hour, and in 80%, within the first 24 hours 2 . Duration of ischemia, as a key determinant of infarct size, has been recognized since the 1970s, guided by the wave front phenomenon, whereby myocyte death is proportionate to the duration of coronary artery occlusion and starts from the endocardium 3 . This knowledge has pushed pharmacological and catheter-based coronary interventions to minimize delay to reperfusion. Nonetheless, the relationship between the probability of death and ischemia time (defined as time from symptoms onset to reperfusion therapy) is non-linear 4 . The major benefit of revascularization of the Infarct related artery [IRA] is obtained when the time of onset of symptoms is less than 12 hours 5, 6 . However, 8% to 40% of all STEMI patients may present later than 12 hours after symptom onset, a patient group commonly designated as late presenters 7 . In clinical practice however the proportion of latecomers is high [GRACE 8 study: 12 % and TETAMI 9 study: 40 %].The clinical benefits of reperfusion in stable STEMI patients presenting 12 hours after symptom onset is controversial, with a few studies demonstrating benefit thought to be unrelated to myocardial savage. Pathophysiological mechanism: The “open artery hypothesis” speculates that restoration of anterograde blood flow to the peri-infarct area is beneficial to the myocardium even late and beyond the time limit set for salvage from myocardial. Salvage of myocardium at risk (“hibernating” myocardium) from death due to apoptosis may be a plausible explanation. Ischemia can indeed induce apoptosis in cardiomyocytes and even late reperfusion may favorably affect the apoptotic cascade 10, 11 . Moreover, ischemia itself stimulates formation of collateral circulation, which in the setting of AMI can serve to preserve some degree of retrograde perfusion, potentially extending the period of viability of myocardium at risk 12 . Viability of stunned myocardium has indeed been demonstrated weeks after AMI, suggesting that reperfusion of the IRA could interrupt the progression from hibernating myocardium to necrotic/apoptotic myocardium 13 . However these theoretically potential benefits have not translated into clinical benefits in various trials. Clinical trials on late presenters treated with catheter based Revascularization have shown conflicting results 14-17 ,whereas imaging studies have suggested a beneficial effect of primary PCI in STEMI patients presenting up to 72 hours after symptom onset 18-20 . Late PCI also has the potential for harm from procedure-related complications, distal embolization of atherothrombotic debris resulting in myocardial injury, and loss of recruitable collateral flow to other coronary territories 21, 22 . Concept of Myocardial salvage Salvage of threatened myocardium is the principal mechanism by which patients with acute myocardial infarction (AMI) benefit from reperfusion. Various modalities although inaccurate can be used to measure the parameters of myocardial salvage, i.e. Electrocardiogram may be used to estimate area at risk (AAR), but not FIS 23 . Indirect measures of salvage can be calculated from angiographic estimates of AAR combined with estimates of FIS by imaging techniques or biochemical markers. Although both CMR and SPECT can be used for the assessment of myocardial salvage, SPECT imaging is the gold standard for assessment of infarct size, left ventricular (LV) function, area at risk [AAR], final infarct size [FIS] myocardial salvage, and myocardial salvage index. Delineation of AAR prior to reperfusion therapy requires tracer availability on a 24 hours basis and technical support for imaging within the following few hours, hence the global lack of data for the same. Evidence contributing lack of symptoms to a nonviable myocardium is lacking and it would be unethical to randomize patients with myocardial infarction (< 48 hours of symptom onset) to a control arm or a non-intervention arm without evaluating the possibility of salvageable myocardium. Effect of primary PCI on ‘latecomers’ presenting 12-48 hours of symptom onset with myocardial salvage as a primary endpoint is less well studied. Hence, we have designed a study to evaluate the effect of primary PCI on myocardial viability in asymptomatic stable STEMI patients presenting 12-48 hours of symptom onset accessed by TC-99m SestaMIBI scan. METHODS We conducted an open label prospective study from January 2020 to December 2023 at U N Mehta institute of cardiology, Ahmedabad and screened all STEMI patients > 18 years of age who presented 12-48 hours of symptom onset (figure 1). U N Mehta institute of cardiology (Affiliated to B J Medical college) is the largest state of art cardiac hospital of India, serving Gujarat and two neighboring states covering over 90.8 million citizens. STEMI was defined as ST-segment elevation ≥0.1 mV in ≥2 contiguous leads or documented new onset left bundle branch block (LBBB). Exclusion criteria included patients with active chest pain, cardiogenic shock (systolic blood pressure <80 mmHg), arrhythmias, congestive heart failure and/or pulmonary edema (Killip class ≥ III), or previous stroke (less than 3 months old), major abdominal or orthopedic surgery, malignancies, pacemaker, previous coronary artery bypass grafting, known or suspected pregnancy, unwillingness to provide written informed consent for participation in the study. All included patients were educated about the research and a written informed consent was obtained. Institutional ethics committee approval was obtained for the respective study at our institution. PCI Protocol All patients received an initial dose of 325 mg of aspirin, clopidogrel (300-600 mg), and 80 mg of atorvastatin along with an intravenous bolus of 70 U/kg of body weight of unfractionated heparin. After the preliminary assessment, patients enrolled were taken to the catheterization laboratory immediately after an initial SPECT Tc-99m sestaMIBI scan. The decision whether to perform a PCI procedure (with or without stenting) or to refer the patient for coronary artery bypass graft surgery was made by primary operator on the basis of lesion severity, anatomy, calcium burden and TIMI flow of the infarct-related artery. Patients who suffered intra-operative hypotension needing catecholamines, arrhythmias, coronary complications [dissection or perforation] and those requiring revascularization of non-infarct related artery were excluded from the study. Post revascularization all patients were advocated dual antiplatelet therapy for one year [Aspirin (75mg) + Ticagrelor (180 mg) or Aspirin (75mg) + Clopidogrel (150 mg)] as per the discretion of treating and follow up physician. Successfully revascularized individuals were subjected to SPECT Tc-99m sestaMIBI scan at 3 months of follow up. SPECT protocol All patients underwent SPECT Tc-99m sestaMIBI scan at the department of Nuclear medicine, U N Mehta institute of cardiology. Scans were evaluated by an experienced professional blinded to patient’s clinical profile. American Heart Association, American College of cardiology, and Society of Nuclear Medicine have defined the standards for plane selection and display orientation for serial myocardial slices generated by SPECT imaging with respective nomenclature i.e. short, vertical long, and horizontal long axes 24 . Scoring left ventricular myocardial perfusion during rest using 17 segments: For the semi-quantitative evaluation of left ventricular perfusion, Sum rest score (SRS) is used to calculate the perfusion score considering both the extent and severity of ischemia in relation to the 17 segments of the polar map. Normal perfusion (as compared with averaged gender-specific data from the population of healthy individuals) is indicated on the scale as a score of 0 (normal perfusion in relation to the control group). Mild and moderate perfusion impairment is indicated by 1 and 2 points, respectively. A score of 3 points indicates significant perfusion impairment, while a score of 4 points is used to indicate total impairment, meaning practically no perfusion. It is estimated that a left ventricular perfusion deficit with a score of 1 or 2 indicates that isotopic activity in this segment is approximately 60% in comparison to the area of radiotracer accumulation specified as 100%. Three points indicate radiotracer activity between 40% and 60%, while 4 points indicate radiotracer activity below 40% in relation to the area with 100% activity respectively. Assessment of AAR by SPECT : After initial myocardial uptake, subsequent 99mTc-Sestamibi clearance is slow without redistribution once bound to viable myocardium 25 . Hence, any myocardial perfusion study will reflect perfusion at the time of tracer injection. Therefore, it is possible to assess AAR by tracer injection before coronary intervention. Assessment of FIS by SPECT : Assessment of FIS by 99mTc-Sestamibi SPECT requires repeated imaging in a stable post-infarction state. FIS imaging must be postponed at least 120 h as assessment of 99mTc-Sestamibi uptake performed at 48–72 h overestimates FIS. A further reduction in infarct size can be seen during the following days to weeks 26 . Optimal timing is better after several weeks. FIS measured by 99mTc-Sestamibi SPECT is consistent with histopathological estimates 27, 28 . A salvage index of ‘1’ indicates complete revival of infarct area at risk, whereas a salvage index of ‘0’ means no change in the infarct size despite revascularization. Endpoints Primary endpoints of our study were LV remodeling indices derived from 99mTc-Sestamibi scan viz area at risk [AAR], final infarct size [FIS], and myocardial salvage index at day 1and at 3 months of follow up respectively and secondary endpoints were the composite of cardiovascular death, recurrent MI, heart failure and stroke. Statistical Analysis Categorical variables were presented as frequencies and percentages and compared using χ2 or Fisher exact test. Continuous variables were tested for normality, and differences were assessed using Student t test or Mann-Whitney U test accordingly. Linear regression analyses between symptom onset to primary PCI as a continuous variable and myocardial salvage index, final infarct size, and LV function were performed. According to the duration of symptom onset to balloon time, patients were sub-classified into three cohorts i.e. cohort A [12-24 hrs.], cohort B [25-36 hrs.] and cohort C [37-48 hrs.] respectively. Association between late-presenting patients and the primary, as well as secondary endpoints, were adjusted for confounders by including any baseline variable with P <0.1 for differences between the groups in multiple regression analyses. Furthermore, ANOVA test and post HOC analysis of cohorts were done to evaluate the effect of primary PCI and its timing on MSI. All analyses were performed using SPSS software. A P value <0.05 was considered statistically significant for all analyses. RESULTS Between January 2020 and December 2023, a total of 264 late presenters were screened for enrollment, 195 patients were certified eligible to undergo SPECT followed by revascularization based on the inclusion criteria established. Out of 195 patients 166 patients underwent SPECT Tc-99m sestaMIBI scan, who were then mobilized to cath lab for revascularization. Successful culprit artery revascularization was performed in 141 patients, while 18 patients were referred for coronary artery bypass grafting, 5 patients required multivessel PCI and 2 patients developed intraoperative coronary complications. As described previously, post Primary PCI subjects were sub-categorized into three cohorts (12 hours each) based on duration of symptom onset, Cohort wise baseline patient characteristic are shown in table 1 respectively. Out of 141 patients who underwent PCI for IRA, 35 patients required intra-coronary glycoprotein IIb/IIIa followed by a systemic infusion and none of the patients underwent thrombus aspiration as per institutional guidelines and operator discretion. PCI peri-procedural data are represented in table 2. Median duration of follow-up after primary PCI was 98 days (range), with 138 patients successfully completing the designed study (figure 1). Out of 141 patients who received primary PCI, only 17 patients underwent right femoral artery cannulation and remaining patients were treated with right radial artery access. Post IRA revascularization more than two third of patients belonging to cohort C (36-48 hours) failed to achieve TIMI III flow which could be hypothesized either to microvascular obstruction or non-viable myocardium. A two way ANOVA analysis (table 3) determines a statistically significant difference in final LVEF achieved by patients who underwent primary PCI 12-24 hours (cohort A) of symptom onset. There was no statistically significant difference in AAR to the onset of symptoms across the cohorts (p = 0.3), however fall in MSI was concurrent with the delay in timing of PCI to symptom onset (figure 4). On post HOC analysis of cohorts, patients from cohort A achieved significantly higher MSI as compared to cohort B and C respectively [Q = 4.18 ( p = .01025) and Q = 5.14 ( p = .00115)]. Table 1. Baseline patient characteristics subcategorized into cohorts based on duration of symptom onset to Primary PCI. Cohort A (n=83) Cohort B (n=37) Cohort C (n=21) Test value (P Value) Age (Mean ± SD) 60.93 ± 12.06 60.81 ± 10.65 57.14 ± 10.92 0.946 (0.391) NS Male (%) 68 (82%) 26 (70%) 17 (81%) 2.15 (0.3412) NS Smoker (%) 43 (52%) 23 (62%) 11 (52%) 1.156 (0.5610) NS Hypertension (%) 25 (30%) 15 (41%) 02 (10%) 6.173 (0.0456) * Diabetes mellitus (%) 14 (17%) 17 (46%) 04 (19%) 12.037 (0.00243) * Dyslipidemia (%) 13 (16%) 06 (16%) 06 (28%) 1.993 (0.369) NS Family history of IHD (%) 10 (12%) 02 (5%) 05 (24%) 4.279 (0.1177) NS Heart rate 86.64 ± 13.95 78.03 ± 10.23 77.43 ± 13.61 7.849 (<0.001) * Systolic BP 140.02 ± 25.98 139.84 ± 21.96 143.52 ± 25.89 0.182 (0.834) NS Diastolic BP 88.92 ± 13.13 87.78 ± 12.28 93.81 ± 14.97 1.504 (0.226) NS Killip class – I (%) 71 (85.50%) 23 (62.10%) 08 (38%) 21.453 (0.000021) * Killip class - II (%) 12 (14.50%) 14 (37.90%) 13 (62%) Infarct localization on Electrocardiogram (%) New onset LBBB 02 (2.40%) 01 (2.70%) 01 (4.80%) 12.609 (0.12602) NS Anterior 47 (56.60%) 22 (59.50%) 18 (85.70%) Posterior 06 (7.20%) 02 (5.40%) 00 (00) Inferior 34 (40.90%) 14 (37.80%) 02 (9.50%) Lateral 02 (2.40%) 03 (8.10%) 00 (00) 2D Echocardiogram (M-mode) LVEF Day 1 36.02 ± 6.79 35.54 ± 9.41 35.85 ± 7.50 0.951 NS Final LVEF 48.25 ± 9.42 39.75 ± 10.95 37.95 ± 10.17 <0.0001 * Table 2. Peri-procedural cohort wise data undergoing primary PCI post SPECT Tc-99m sestaMIBI scan (day 1). Cohort A (n=83) Cohort B (n=37) Cohort C (n=21) P Value Location of infarct related lesion Left main Left anterior descending 57 (68.70%) 26 (70%) 19 (90.50%) 9.883 (0.0424) * Left circumflex 08 (9.60%) 08 (21.60%) 02 (9.50%) Right coronary 23 (27.70%) 09 (24.30%) 00 (00) Pre-PCI TIMI flow 0 66 (79.50%) 24 (64.90%) 20 (95%) 10.112 (0.0385) * 1 16 (19.30%) 10 (27%) 01 (5%) 2 01 (1.20%) 03 (8.10%) 00 (00) 3 00 (00) 00 (00) 00 (00) Post-PCI TIMI flow 0 00 (00) 00 (00) 00 (00) 18.384 (0.0001) * 1 00 (00) 00 (00) 00 (00) 2 07 (8.50%) 01 (2.70%) 08 (38%) 3 76 (91.50%) 36 (97.30%) 13 (62%) Table 3. Cohort wise data of LV indices derived from SPECT Tc-99m sestaMIBI scan SPECT Tc-99m sestaMIBI parameters Cohort A (n=83) Cohort B (n=37) Cohort C (n=21) P Value Area at risk 35.44 ± 12.79 31.90 ± 10.18 35.14 ± 9.23 0.300 NS Final Infarct size 16.39 ± 9.87 19.36 ± 7.48 24.19 ± 11.30 0.0043 * Myocardial salvage index 0.53 ± 0.23 0.38 ± 0.18 0.34 ± 0.19 0.00006 * Although the AAR was comparable throughout cohorts, on post HOC analysis a statistically significant reduction in the final infarct size was seen among patients in cohort A vs C [Q = 4.72 ( p = .00309)], while a reduction of FIS in cohort B and cohort C were obvious but statistically insignificant (table 4). Myocardial salvage index was smaller in late presenters, with no statistically significant difference among cohort B & cohort C [Q = 0.96 ( p = .77697)]. A substantial salvage index (i.e. MSI >0.5) was achieved among 59 % of patients in cohort A and in not more than 35 % of patients in cohort B and C respectively. Timing of Primary PCI did not have a positive impact on MSI in patients presenting 24-48 hours of symptom onset [table 5]. Table 4: Post HOC analysis of FIS among cohorts. Pairwise Comparisons HSD .05 = 5.5339 Q .05 = 3.3515 Q .01 = 4.1910 HSD .01 = 6.9200 T 1 :T 2 M 1 = 16.39 2.97 Q = 1.80 ( p = .41359) M 2 = 19.36 T 1 :T 3 M 1 = 16.39 7.8 Q = 4.72 ( p = .00309) M 3 = 24.19 T 2 :T 3 M 2 = 19.36 4.83 Q = 2.93 ( p = .10034) M 3 = 24.19 Table 5: Post HOC analysis of MSI among cohorts. Pairwise Comparisons HSD .05 = 0.1228 Q .05 = 3.3515 Q .01 = 4.1910 HSD .01 = 0.1535 T 1 :T 2 M 1 = 0.53 0.15 Q = 4.18 ( p = .01025) M 2 = 0.38 T 1 :T 3 M 1 = 0.53 0.19 Q = 5.14 ( p = .00115) M 3 = 0.34 T 2 :T 3 M 2 = 0.38 0.04 Q = 0.96 ( p = .77697) M 3 = 0.34 Throughout the study cohorts, delaying the duration of performing Primary PCI from symptom onset was associated with larger AAR & FIS although with a lower correlation coefficient (figure 2). While evaluation MSI against timing of Primary PCI, a moderately negative (R= -0.41) relation exists between these two variables which is indicative of patients who underwent late PCI had a linear correlation with reduced myocardial salvage Index (figure 3b and 4). DISCUSSION Optimal treatment for patients who have acute myocardial infarction with ST-segment elevation includes early reperfusion with primary percutaneous coronary intervention (PCI) or thrombolytic therapy. However, approximately one third of eligible patients do not receive early reperfusion therapy, in many cases because of late presentation. Evidence on behavior and the fate of myocardium, after revascularization in asymptomatic STEMI patients presenting beyond 12 hours is scarce. To study the efficacy of Primary PCI in patients presenting 12-48 hours of symptom onset, we enrolled 141 patients for Tc-99m sestaMIBI scan followed by IRA revascularization and sub categorized them based on the timing of Primary PCI to symptom onset, into three cohorts of 12 hours each. 138 patients completed the designed study with a follow up Tc-99m sestaMIBI scan. We found that duration of symptom onset did not affect the initial LVEF and AAR throughout the cohorts. Despite having a comparable AAR, cohorts B and C had larger FIS and poorer MSI. Also, patients from Cohort A achieved higher final LVEF compared to rest of the subjects. As our study enrolled stable STEMI patients, unstable patients were systemically excluded from based on vitals and killip’s class at presentation. The mean pulse of the patients enrolled was 86/min with a mean SBP of 140 (± 25.98) mmHg and mean DBP 89(± 13.20) mmHg. 27 % of patients were in Killip’s class II at presentation and rest of the 102 individuals were in Killip’s class I. Albert Schömig et al 29 in BRAVE II also excluded patients in killip’s class III and IV, enrolling 81 % of patients in Killip’s class I and 19 % of patients in Killip’s class II, their patients had an mean pulse of 72/min, mean SBP of 140 mmHg and a mean DBP of 80 mmHg. Doo Sun Sim et al 30 in their study found that, 83 % of patients were in Killip’s class I and 17 % of patients were in Killip’s class II. James E Udelson et al 31 in OAT-NUC trial had 82 % patients in killip’s class I and 18 % of patients in killip’s class II-IV. Hyperdynamic apex was observed in few patients with anemia, none of them had pericardial rub or a murmur. Among the patients who presented with STEMI, 62% of patients suffered an anterior wall MI followed by inferior wall MI (25 %), and few individuals suffered infarction of posterior wall (9%) associated with IWMI. Patients from cohort C predominantly suffered anterior wall infarction and achieved an overall smaller MSI. On coronary angiogram, 63 % had occlusion of single vessel involving left anterior descending, 18 % patients involving right coronary artery and 8.5 % patients involving circumflex artery respectively. 14 (9.9 %) individuals had double vessel disease who’s SYNTAX score were < 22. Albert Schömig et al 29 in BRAVE II found that 63 % of individuals had AWMI and 35 % had IWMI subsequently 37 % of patients had a lesion in LAD, 31 % in RCA and 29 % in LCX. All of our patients underwent PTCA + stenting of IRA with 3 rd generation DES. TIMI III flow was achieved in 88 % of our patients in comparison to 87 % in BRAVE II trial. Echocardiographic assessment at presentation showed that Initial mean LV function was 35.87 %( ±7.61) and final mean LVEF mean follow up of 98 days was 44.54 % (±10.87) figure. A statistically significant difference (P=<0.0001), was noted in final LVEF in total cohorts. Lars Nepper-Christensen et al 32 found that in his patients initial mean LVEF was 45 % and final LVEF was 51 % which was statistically significant. Shoichi Miyamoto et al 33 had also found a statistically significant difference in initial (48%) and chronic LVEF (51 %). All of the patients underwent Tc99m-sestaMIBI scan prior to revascularization, area at risk at day 1 and final infarct size at follow up is expressed as % of infarct size, mean AAR was 34.47 %(±11.70) and mean final infarct size was 18.29% (±9.85), with a mean MSI of 0.46 (± 0.22) in overall cohorts. Lars Nepper-Christensen et al 32 studied that AAR, FIS and MSI of patients enrolled in his study were 34 %, 13 % and 0.58 respectively. In total cohorts, an MSI of > 0.50 was attained among 36 %, 8% and 5 % of patients from cohort A, B, and C respectively (figure 5). We also found that age (primary event) did not have any statistical significance over myocardial salvage index. Myocardial salvage and infarct size may in addition to duration of ischemia be affected by peri procedural events, such as distal embolization, no-reflow phenomenon, or lethal reperfusion injury. It could be speculated that the risk of distal embolization and no-reflow increases in late presenters as the thrombotic occlusion of the coronary artery consolidates over time 35 . On analysis of secondary endpoints among overall cohorts, 13 % of patients had recurrent heart failure hospitalization and 27 % of patients needed optimization of heart failure therapy as a result of worsening functional class (NYHA class ≥ II). Aforementioned patients predominantly suffered an AWMI (65 %), with a mean final LVEF of 38.87 (±9.77) on follow up. The mean duration of Primary PCI to symptoms in these patients was 24.60 (±9.11) hours with a mean MSI of 0.31 (± 0.16). Although the final LVEF and FIS observed was statistically significant (p<0.05), it did not contribute clinically in improving functional class, which also solidifies our understanding of ischemic heart failure pathology being multifactorial. Also, in this group of patients mean AAR (33.82 (± 10.62)) was comparable to total cohort, however primary PCI did not exert a positive clinical impact (figure 6). On further analysis of secondary endpoints one patients suffered CV death, 2 patients suffered non hemorrhagic stroke and none of the patients had recurrent MI. In BRAVE II trial cumulative incidence of the composite of death, recurrent MI, or stroke was 4.9%. Doo Sun Sim et al 30 reported that 1.7 % of patients had MI/death at12 months. Patrick W. McNair et al 34 in their study found that 16 % of patients had heart failure, 4 % of patients died and 2 % of patients suffered stroke. Conclusion Asymptomatic stable STEMI patients presenting 12–24 hours of symptom onset to PCI had a significant benefit with primary PCI with a lesser final infarct size and a larger myocardial savage index. Despite a comparable AAR across the cohorts, MSI fell sharply in patients undergoing primary PCI 24–48 hours of symptom onset with a larger final infarct size, warranting a viability guided revascularization. Although primary PCI improved final LVEF and MSI in patients who suffered ischemic heart failure, gain in parameters alone was insufficient in endeavoring a positive clinical impact on the course of ischemic heart failure, contemplating a multifactorial pathology. Limitations Despite having a large number of patients who qualified the enrollment criteria, our study population was smaller due to the restricted availability of nuclear material. Infarct size derived from Tc-99m sestaMIBI could possibly have an Observer bias as it is a semi-quantitative analysis with a feedback from reporter, also LVEF calculated at presentation and at follow up was reported by multiple observers and may carry a subjective inter-observer bias. Declarations Acknowledgments We would like to thank Dr. R K Patel, Dr Jayesh Prajapati, Dr Tanmay Agarwal, Dr Mithilesh Kulkarni, Dr. Amita Goswami and the staff, Dept. of Nuclear Medicine, U N Mehta institute of Cardiology, Ahmedabad, Gujarat, India. Disclosures : - None Conflict of interest : - None Author Contribution Author M.P. and S.T. were primarily responsible for enrolling patients eligible for this study and as well as performing PCI in STEMI- late comersAuthor S.S. is a senior cardiologist and unit chief who made decisions on revascularization and technical aspectsAuthor V.P. is qualified nuclear medicine physician who was primary responsible to report TC-99m sestaMIBI scan reportsAuthor V.K. played role as a statistical expert and helped deriving complex post HOC analysisAurthor J.J. V.P. and P.S. made sure study is blinded, helped in coordination and adressed patient greviencesAll authors reviewed the manuscript References Qian L, Ji KT, Nan JL, Lu Q, Zhu YJ, Wang LP et al (2013) Factors associated with decision time for patients with ST-segment elevation acute myocardial infarction. J Zhejiang Univ Sci 14(8):754–758 Piegas LS, Feitosa G, Mattos LA, Nicolau Jc, Rossi Neto JM, Timerman A et al (2009) ;Sociedade Brasileira de Cardiologia. IV Diretrizes da SBC sobre tratamento do infarto agudo do miocárdio com supradesnível do segmento ST. Arq Bras Cardiol 93(6 supl 2):e179–e264 Reimer KA, Jennings RB (1979) The wavefront phenomenon of myocardial ischemic cell death. II. Transmural progression of necrosis within the framework of ischemic bed size (myocardium at risk) and collateral flow. Lab Invest 40:633–644 Gersh BJ, Stone GW, White HD, Holmes DR Jr. (2005) Pharmacological facilitation of primary percutaneous coronary intervention for acute myocardial infarction: is the slope of the curve the shape of the future? JAMA 293:979–986. 10.1001/jama.293.8.979 Ibanez B, James S, Agewall S, Antunes MJ, Bucciarelli-Ducci C, Bueno H, Caforio ALP, Crea F, Goudevenos JA, Halvorsen S, Hindricks G, Kastrati A, Lenzen MJ, Prescott E, Roffi M, Valgimigli M, Varenhorst C, Vranckx P, Widimský P, ESC Scientific Document Group (2018) 2017 ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation: the Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC). Eur Heart J 39:119–177. 10.1093/eurheartj/ehx393 O’Gara PT, Kushner FG, Ascheim DD, Casey DE, Chung MK, de Lemos JA, Ettinger SM, Fang JC, Fesmire FM, Franklin BA, Granger CB, Krumholz HM, Linderbaum JA, Morrow DA, Newby LK, Ornato JP, Ou N, Radford MJ, Tamis-Holland JE, Tommaso CL, Tracy CM, Woo YJ, Zhao DX (2013) 2013 ACCF/AHA Guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation 127:e362–e425. 10.1161/CIR.0b013e3182742cf6 Schömig A, Ndrepepa G, Kastrati A (2006) Late myocardial salvage: time to recognize its reality in the reperfusion therapy of acute myocardial infarction. Eur Heart J 27:1900–1907. 10.1093/eurheartj/ehl174 Eagle KA, Nallamothu BK, Mehta RH et al (2008) Trends in acute reperfusion therapy for ST-segment elevation myocardial infarction from 1999 to 2006: we are getting better but we have got a long way to go. Eur Heart J 29:609–617 Cohen M, Gensini GF, Maritz F et al (2003) TETAMI Investigators - Prospective evaluation of clinical outcomes after acute ST-segment elevation myocardial infarction in patients who are ineligible for reperfusion therapy: preliminary results from the TETAMI registry and randomized trial. Circulation 3:14–21 Abbate A, Bussani R, Biondi-Zoccai GG et al (2002) Persistent infarct related artery occlusion is associated with an increased myocardial apoptosis at postmortem examination in humans late after an acute myocardial infarction. Circulation 106:1051–1054 Abbate A, Bussani R, Biondi-Zoccai GG et al (2005) Infarct-related artery occlusion, tissue markers of ischaemia, and increased apoptosis in the peri-infarct viable myocardium. Eur Heart J 26:2039–2045 Sabia PJ, Powers ER, Ragosta M, Sarembock U, Burwell LR, Kaul S (1992) An association between collateral blood flow and myocardial viability in patients with recent myocardial infarction. N Engl J Med 327:1825–1831 Brunken R, Tillisch J, Schwaiger M et al (1986) Regional perfusion, glucose metabolism, and wall motion in patients with chronic electrocardiographic Q wave infarctions: evidence of persistence of viable tissue in some infarct regions by positron emission tomography. Circulation 73:951–963 Abbate A, Biondi-Zoccai GG, Appleton DL, Erne P, Schoenenberger AW, Lipinski MJ, Agostoni P, Sheiban I, Vetrovec GW (2008) Survival and cardiac remodeling benefits in patients undergoing late percutaneous coronary intervention of the infarct-related artery: evidence from a meta-analysis of randomized controlled trials. J Am Coll Cardiol 51:956–964. 10.1016/j.jacc.2007.11.062 Ioannidis JP, Katritsis DG (2007) Percutaneous coronary intervention for late reperfusion after myocardial infarction in stable patients. Am Heart J 154:1065–1071. 10.1016/j.ahj.2007.07.049 Hochman JS, Lamas GA, Buller CE, Dzavik V, Reynolds HR, Abramsky SJ, Forman S, Ruzyllo W, Maggioni AP, White H, Sadowski Z, Carvalho AC, Rankin JM, Renkin JP, Steg PG, Mascette AM, Sopko G, Pfisterer J, Fridrich V, Mark DB, Knatterud GL (2006) Occluded Artery Trial Investigators. Coronary intervention for persistent occlusion after myocardial infarction. N Engl J Med . ;355:2395–2407. 10.1056/NEJMoa066139 Gierlotka M, Gasior M, Wilczek K, Hawranek M, Szkodzinski J, Paczek P, Lekston A, Kalarus Z, Zembala M, Polonski L (2011) Reperfusion by primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction within 12 to 24 hours of the onset of symptoms (from a Prospective National Observational Study [PL-ACS]). Am J Cardiol 107:501–508. 10.1016/j.amjcard.2010.10.008 Schömig A, Mehilli J, Antoniucci D, Ndrepepa G, Markwardt C, Di Pede F, Nekolla SG, Schlotterbeck K, Schühlen H, Pache J, Seyfarth M, Martinoff S, Benzer W, Schmitt C, Dirschinger J, Schwaiger M, Kastrati A (2005) Beyond 12 hours Reperfusion Alternative Evaluation (BRAVE-2) Trial Investigators. Mechanical reperfusion in patients with acute myocardial infarction presenting more than 12 hours from symptom onset: a randomized controlled trial. JAMA 293:2865–2872. 10.1001/jama.293.23.2865 Busk M, Kaltoft A, Nielsen SS, Bøttcher M, Rehling M, Thuesen L, Bøtker HE, Lassen JF, Christiansen EH, Krusell LR, Andersen HR, Nielsen TT, Kristensen SD (2009) Infarct size and myocardial salvage after primary angioplasty in patients presenting with symptoms for < 12 h vs. 12–72 h. Eur Heart J 30:1322–1330. 10.1093/eurheartj/ehp113 Stiermaier T, Eitel I, de Waha S, Pöss J, Fuernau G, Thiele H, Desch S (2017) Myocardial salvage after primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction presenting early versus late after symptom onset. Int J Cardiovasc Imaging 33:1571–1579. 10.1007/s10554-017-1143-x Monteiro P, Antunes A, Goncalves LM, Providencia LA (2003) Long-term clinical impact of coronary-collateral vessels after acute myocardial infarction. Rev Port Cardiol 22:1051–1061 Singh M, Rihal CS, Lennon RJ, Garratt KN, Mathew V, Holmes DR Jr (2005) Prediction of complications following nonemergency percutaneous coronary interventions. Am J Cardiol 96:907–912 van Hellemond IE, Bouwmeester S, Olson CW, Botker HE, Kaltoft AK, Nielsen SS et al (2011) Consideration of QRS complex in addition to ST-segment abnormalities in the estimated ‘risk region’ during acute anterior myocardial infarction. J Electrocardiol 44:370–376 American Heart Association (1992) American College of Cardiology, and Society of Nuclear Medicine. Standardization of cardiac tomographic imaging. Circulation 86:338–339 Okada RD, Williams SJ, Glover DK, Dragatokis D (1988) Cardiac imaging and myocardial kinetics of technetium-tertiary butyl-isonitrile during dipyridamole-induced hyperemia. Am Heart J 116:979–988 Ndrepepa G, Mehilli J, Martinoff S, Schwaiger M, Schomig A, Kastrati A (2007) Evolution of left ventricular ejection fraction and its relationship to infarct size after acute myocardial infarction. J Am Coll Cardiol 50:149–156 Medrano R, Lowry RW, Young JB, Weilbaecher DG, Michael LH, Afridi I et al (1996) Assessment of Myocardial viability with 99mTc sestamibi in patients undergoing cardiac transplantation. A scintigraphic/pathological study. Circulation 94:1010–1017 Kristensen J, Mortensen UM, Nielsen SS, Maeng M, Kaltoft A, Nielsen TT et al (2004) Myocardial perfusion imaging with Tc-99m sestamibi early after reperfusion reliably reflects infarct size reduction by ischaemic preconditioning in an experimental porcine model. Nucl Med Com 25:495–500 Schomig A, Mehilli J, Antoniucci D et al (2005) Mechanical reperfusion in patients with acute myocardial infarction presenting more than 12 hours from symptom onset: a randomized controlled trial. JAMA 293:2865–2872 Sim DS, Jeong MH, Ahn Y, Kim YJ, Chae SC, Hong TJ, Seong IW, Chae JK, Kim CJ, Cho MC, Rha SW, Bae JH, Seung KB (2012) Park, Korea Acute Myocardial Infarction Registry (KAMIR) Investigators Benefit of percutaneous coronary intervention in early latecomers with acute ST-segment elevation myocardial infarction. Am J Cardiol 110:1275–1281 Udelson JE, Pearte CA, Kimmelstiel CD, Kruk M, Kufera JA, Forman SA, Teresinska A, Bychowiec B, Marin-Neto JA, Höchtl T, Cohen EA, Caramori P, Busz-Papiez B, Adlbrecht C, Sadowski ZP, Ruzyllo W, Kinan DJ, Lamas GA, Hochman JS (2011) The Occluded Artery Trial (OAT) Viability Ancillary Study (OAT-NUC): influence of infarct zone viability on left ventricular remodeling after percutaneous coronary intervention vs. optimal medical therapy alone. Am Heart J 161:611–621 Nepper-Christensen L, Lønborg J, Høfsten DE, Ahtarovski KA, Bang LE, Helqvist S, Kyhl K, Køber L, Kelbæk H, Vejlstrup N, Holmvang L, Engstrøm T (2018) Benefit from reperfusion with primary percutaneous coronary intervention beyond 12 hours of symptom duration in patients with ST-segment–elevation myocardial infarction. Circ Cardiovasc Interv 11:e006842. 10.1161/CIRCINTERVENTIONS.118.006842 Miyamoto S, Goto Y, Fujita M et al (2001) Late reperfusion (6–24 hours after onset) improves left ventricular function in patients with acute myocardial infarction. Jpn Circ J 65:389–394 McNair PW, Bilchick KC, Keeley EC (2019) Very late presentation in ST elevation myocardial infarction: predictors and long-term mortality. Int J Cardiol Heart Vasc 22:156–159 Lønborg J, Engstrøm T, Ahtarovski KA, Nepper-Christensen L, Helqvist S, Vejlstrup N, Kyhl K, Schoos MM, Ghotbi A, Göransson C, Bertelsen L, Holmvang L, Pedersen F, Jørgensen E, Saunamäki K, Clemmensen P, De Backer O, Kløvgaard L, Høfsten DE, Køber L, Kelbak H (2017) DANAMI-3 Investigators. Myocardial damage in patients with deferred stenting after STEMI: a DANAMI-3-DEFER substudy. J Am Coll Cardiol 69:2794–2804. 10.1016/j.jacc.2017.03.601 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4163687","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":284016971,"identity":"bcbef62c-09ea-4136-a3b0-690d87ac26ce","order_by":0,"name":"Manjunath Suresh Pandit","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3UlEQVRIiWNgGAWjYJACAxDBxt58gIGxgRQtfDzHEojXAgZyEjkGxGnRbT97oJiHoS6PjefMN4mfO2zkGNgPH92AT4vZmbwEYx6Gw8Vs7L3bJHvPpBkz8KSl3cCr5UCOAVDLgcQ2nrPbJHjbDic2SPCY4ddy/g1IS11im0TOM8m/RGm5AbaFGaSFTZo4W268MTCcA/ILzzFja9m2NGM2gn45n2Nm8AYYYvLtzQ9vvm2zkeNnP3wMrxYgYDNg/MeQAGSwSIC5BJSDAPMDIAHSwvyBCNWjYBSMglEwAgEAkL1Hqn9JHUwAAAAASUVORK5CYII=","orcid":"","institution":"U N Mehta institute of cardiology, B J Medical college","correspondingAuthor":true,"prefix":"","firstName":"Manjunath","middleName":"Suresh","lastName":"Pandit","suffix":""},{"id":284016972,"identity":"1e4cef2b-e430-4fb8-91a9-03d41bfcdd81","order_by":1,"name":"Sibasis Sahoo","email":"","orcid":"","institution":"U N Mehta institute of cardiology","correspondingAuthor":false,"prefix":"","firstName":"Sibasis","middleName":"","lastName":"Sahoo","suffix":""},{"id":284016974,"identity":"157d11d0-e684-4f26-82d5-1427c511b21c","order_by":2,"name":"Vishalkumar M Patel","email":"","orcid":"","institution":"U N Mehta institute of cardiology","correspondingAuthor":false,"prefix":"","firstName":"Vishalkumar","middleName":"M","lastName":"Patel","suffix":""},{"id":284016975,"identity":"7b743f63-a3cf-41bc-9f57-9a353c7234ff","order_by":3,"name":"Senthilraj Thangasami","email":"","orcid":"","institution":"Apollo hospitals","correspondingAuthor":false,"prefix":"","firstName":"Senthilraj","middleName":"","lastName":"Thangasami","suffix":""},{"id":284016976,"identity":"e38f03e1-d9a2-4358-bea7-221741425d26","order_by":4,"name":"Vinayak H Kashyap","email":"","orcid":"","institution":"U N Mehta institute of cardiology, B J Medical college","correspondingAuthor":false,"prefix":"","firstName":"Vinayak","middleName":"H","lastName":"Kashyap","suffix":""},{"id":284016977,"identity":"cdf7fbe8-04ad-47f8-9e22-d9d46be990f4","order_by":5,"name":"Jevin Jameria","email":"","orcid":"","institution":"Nirali hospital","correspondingAuthor":false,"prefix":"","firstName":"Jevin","middleName":"","lastName":"Jameria","suffix":""},{"id":284016978,"identity":"995bc3be-a5f4-4988-a943-701cf4c64c32","order_by":6,"name":"Vimlesh Pandey","email":"","orcid":"","institution":"U N Mehta institute of cardiology","correspondingAuthor":false,"prefix":"","firstName":"Vimlesh","middleName":"","lastName":"Pandey","suffix":""},{"id":284016979,"identity":"15769589-1150-4e25-93e2-6ec464ce8b26","order_by":7,"name":"Parth Shanishwara","email":"","orcid":"","institution":"U N Mehta institute of cardiology","correspondingAuthor":false,"prefix":"","firstName":"Parth","middleName":"","lastName":"Shanishwara","suffix":""}],"badges":[],"createdAt":"2024-03-25 13:31:57","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4163687/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4163687/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":53746764,"identity":"ab6ead41-708c-480e-a78e-900ab660c746","added_by":"auto","created_at":"2024-03-29 17:59:14","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":62237,"visible":true,"origin":"","legend":"\u003cp\u003eStudy design\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4163687/v1/22a223602146a9b1ea84001e.png"},{"id":53746189,"identity":"20f46b3b-9bd3-4ce6-b16e-73ac4908dca6","added_by":"auto","created_at":"2024-03-29 17:51:14","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":54150,"visible":true,"origin":"","legend":"\u003cp\u003eRegression analysis of area at risk (a) and final infarct size (b) against hours to primary PCI after symptom onset\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4163687/v1/855ee7c28ee74f93baa89995.png"},{"id":53746187,"identity":"02d30492-0e3e-4d39-afbe-bfa39fa15783","added_by":"auto","created_at":"2024-03-29 17:51:14","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":68628,"visible":true,"origin":"","legend":"\u003cp\u003eRegression analysis of myocardial salvage index against hours to primary PCI after symptom onset (a) and age (b) respectively.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4163687/v1/d03d057975b3e26c5b0f84ce.png"},{"id":53746185,"identity":"1bf34361-eef6-44ef-8452-37fa78c91c35","added_by":"auto","created_at":"2024-03-29 17:51:14","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":31206,"visible":true,"origin":"","legend":"\u003cp\u003eshowing trends in myocardial salvage index with symptom duration\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4163687/v1/014c5c8ea8c82129c68242f1.png"},{"id":53746188,"identity":"1fb3ea3e-fee8-46a5-a756-e82c02074972","added_by":"auto","created_at":"2024-03-29 17:51:14","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":22606,"visible":true,"origin":"","legend":"\u003cp\u003ePercentage of patients achieving myocardial salvage index of ≥0.50 stratified by duration of symptom onset to primary percutaneous coronary intervention.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4163687/v1/f4ce9c5dac08ae9c5dc3b718.png"},{"id":53746190,"identity":"c6843a3f-8ced-41b5-93c6-c60b328106c9","added_by":"auto","created_at":"2024-03-29 17:51:15","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":963231,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e: Tc-99msestaMIBI on day 1, Illustration of a patient from our study with recurrent heart failure hospitalization, who had presented with AWMI and a complete occlusion of proximal LAD (AAR= 45.57 %), 6 \u003cstrong\u003e(b)\u003c/strong\u003e: Tc-99msestaMIBI on day 91of post revascularization (FIS = 44.1 %, Myocardial salvage index: \u003cstrong\u003e0.03\u003c/strong\u003e), timing of Primary PCI: 38\u003csup\u003eth\u003c/sup\u003e hour of symptom.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4163687/v1/f824e7b532870877913b0e50.png"},{"id":53746191,"identity":"a71aa3c7-42f6-45a9-a816-905a93b56b23","added_by":"auto","created_at":"2024-03-29 17:51:15","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":1046206,"visible":true,"origin":"","legend":"\u003cp\u003e(a) : Tc-99msestaMIBI on day 1 illustrates a patient from our study who presented with inferior wall MI. Coronary angiography revealed a CTO lesion in LAD and a complete thrombotic occlusion of RCA (AAR = 51.45%),7 (b) illustrates that post PCI (IRA only), viability was preserved in the LV segments supplied by RCA and a reduction in the infarct size of LV segments supplied by LAD, through improved collateral flow (FIS = 27.93 %, Myocardial salvage index: 0.45) timing of Primary PCI: 25\u003csup\u003eth\u003c/sup\u003e hour of symptom.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-4163687/v1/247ce5c5f7b0bb1b2e2c5ebc.png"},{"id":72256420,"identity":"fc9d4438-2ba9-48dc-b9ef-3d0d21b4cc67","added_by":"auto","created_at":"2024-12-24 09:47:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2571713,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4163687/v1/a39c0662-09c9-4b46-aa33-c29b6144056c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effect of Primary PCI in asymptomatic STEMI patients presenting 12-48 hours of symptom onset, on myocardial viability assessed on SPECT - ‘EPITOME-99’","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eIn patients with acute ST-segment elevation myocardial infarction (STEMI), the time interval between symptom onset and hospital arrival is one of the most consistent predictors of mortality\u003csup\u003e1\u003c/sup\u003e. Most deaths occur at the start of disease manifestation, and in the 40% to 65% of the cases, death occurs within the first hour, and in 80%, within the first 24 hours\u003csup\u003e2\u003c/sup\u003e. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDuration of ischemia, as a key determinant of infarct size, has been recognized since the 1970s, guided by the wave front phenomenon, whereby myocyte death is proportionate to the duration of coronary artery occlusion and starts from the endocardium\u003csup\u003e3\u003c/sup\u003e. This knowledge has pushed pharmacological and catheter-based coronary interventions to minimize delay to reperfusion. Nonetheless, the relationship between the probability of death and ischemia time (defined as time from symptoms onset to reperfusion therapy) is non-linear\u003csup\u003e4\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe major benefit of revascularization of the Infarct related artery [IRA] is obtained when the time of onset of symptoms is less than 12 hours\u003csup\u003e5, 6\u003c/sup\u003e. However, 8% to 40% of all STEMI patients may present later than 12 hours after symptom onset, a patient group commonly designated as late presenters\u003csup\u003e7\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eIn clinical practice however the proportion of latecomers is high [GRACE\u003csup\u003e8\u003c/sup\u003e study: 12 % and TETAMI\u003csup\u003e9\u003c/sup\u003e study: 40 %].The clinical benefits of reperfusion in stable STEMI patients presenting 12 hours after symptom onset is controversial, with a few studies demonstrating benefit thought to be unrelated to myocardial savage.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePathophysiological mechanism: \u0026nbsp;\u003c/strong\u003eThe \u0026ldquo;open artery hypothesis\u0026rdquo; speculates that restoration of anterograde blood flow to the peri-infarct area is beneficial to the myocardium even late and beyond the time limit set for salvage from myocardial. Salvage of myocardium at risk (\u0026ldquo;hibernating\u0026rdquo; myocardium) from death due to apoptosis may be a plausible explanation. Ischemia can indeed induce apoptosis in cardiomyocytes and even late reperfusion may favorably affect the apoptotic cascade \u003csup\u003e10, 11\u003c/sup\u003e. Moreover, ischemia itself stimulates formation of collateral circulation, which in the setting of AMI can serve to preserve some degree of retrograde perfusion, potentially extending the period of viability of myocardium at risk \u003csup\u003e12\u003c/sup\u003e. Viability of stunned myocardium has indeed been demonstrated weeks after AMI, suggesting that reperfusion of the IRA could interrupt the progression from hibernating myocardium to necrotic/apoptotic myocardium \u003csup\u003e13\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eHowever these theoretically potential benefits have not translated into clinical benefits in various trials. Clinical trials on late presenters treated with catheter based Revascularization have shown conflicting results\u003csup\u003e14-17\u003c/sup\u003e ,whereas imaging studies have suggested a beneficial effect of primary PCI in STEMI patients presenting up to 72 hours after symptom onset\u003csup\u003e18-20\u003c/sup\u003e. Late PCI also has the potential for harm from procedure-related complications, distal embolization of atherothrombotic debris resulting in myocardial injury, and loss of recruitable collateral flow to other coronary territories \u003csup\u003e21, 22\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConcept of Myocardial salvage\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSalvage of threatened myocardium is the principal mechanism by which patients with acute myocardial infarction (AMI) benefit from reperfusion. Various modalities although inaccurate can be used to measure the parameters of myocardial salvage, i.e. Electrocardiogram may be used to estimate area at risk (AAR), but not FIS\u003csup\u003e23\u003c/sup\u003e. Indirect measures of salvage can be calculated from angiographic estimates of AAR combined with estimates of FIS by imaging techniques or biochemical markers.\u003c/p\u003e\n\u003cp\u003eAlthough both CMR and SPECT can be used for the assessment of myocardial salvage, SPECT imaging is the gold standard for assessment of infarct size, left ventricular (LV) function, area at risk [AAR], final infarct size [FIS] myocardial salvage, and myocardial salvage index. Delineation of\u0026nbsp;AAR prior to reperfusion therapy requires tracer availability on a 24 hours basis and technical support for imaging within the following few hours, hence the global lack of data for the same.\u003c/p\u003e\n\u003cp\u003eEvidence contributing lack of symptoms to a nonviable myocardium is lacking and it would be unethical to randomize patients with myocardial infarction (\u0026lt; 48 hours of symptom onset) to a control arm or a non-intervention arm without evaluating the possibility of salvageable myocardium.\u003c/p\u003e\n\u003cp\u003eEffect of primary PCI on \u0026lsquo;latecomers\u0026rsquo; presenting 12-48 hours of symptom onset with myocardial salvage as a primary endpoint is less well studied. Hence, we have designed a study to evaluate the effect of primary PCI on myocardial viability in asymptomatic stable STEMI patients presenting 12-48 hours of symptom onset accessed by TC-99m SestaMIBI scan.\u0026nbsp;\u003c/p\u003e"},{"header":"METHODS","content":"\u003cp\u003eWe conducted an\u0026nbsp;open label prospective study from January 2020 to December 2023\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eat U N Mehta institute of cardiology, Ahmedabad and screened all STEMI patients \u0026gt; 18 years of age who presented 12-48 hours of symptom onset (figure 1). U N Mehta institute of cardiology (Affiliated to B J Medical college) is the largest state of art cardiac hospital of India, serving Gujarat and two neighboring states covering over 90.8 million citizens. STEMI was defined as ST-segment elevation\u0026nbsp;\u0026ge;0.1 mV in\u0026nbsp;\u0026ge;2 contiguous leads or documented new onset left bundle branch block (LBBB). Exclusion criteria included patients with active chest pain, cardiogenic shock (systolic blood pressure \u0026lt;80 mmHg), arrhythmias, congestive heart failure and/or pulmonary edema (Killip class \u0026ge; III), or previous stroke (less than 3 months old), major abdominal or orthopedic surgery, malignancies, pacemaker, previous coronary artery bypass grafting, known or suspected pregnancy, unwillingness to provide written informed consent for participation in the study. All included patients were educated about the research and a written informed consent was obtained. Institutional ethics committee approval was obtained for the respective study at our institution.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePCI Protocol\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll patients received an initial dose of 325 mg of aspirin, clopidogrel (300-600 mg), and 80 mg of atorvastatin along with an intravenous bolus of 70 U/kg of body weight of unfractionated heparin. After the\u0026nbsp;preliminary assessment, patients enrolled were taken to the catheterization laboratory immediately after an initial\u0026nbsp;SPECT Tc-99m sestaMIBI scan. The decision whether to perform a PCI procedure (with or without stenting) or to refer the patient for coronary artery bypass graft surgery was made by primary operator on the basis of lesion severity, anatomy, calcium burden and TIMI flow of the infarct-related artery. Patients who suffered intra-operative hypotension needing catecholamines, arrhythmias, coronary complications [dissection or perforation] and those requiring revascularization of non-infarct related artery were excluded from the study. Post revascularization all patients were advocated dual antiplatelet therapy for one year [Aspirin (75mg) + Ticagrelor (180 mg) or Aspirin (75mg) + Clopidogrel (150 mg)] as per the discretion of treating and follow up physician. Successfully revascularized individuals were subjected to\u0026nbsp;SPECT Tc-99m sestaMIBI scan\u0026nbsp;at 3 months of follow up.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSPECT protocol\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll patients underwent\u0026nbsp;SPECT Tc-99m sestaMIBI scan at the department of Nuclear medicine, U N Mehta institute of cardiology. Scans were evaluated by an experienced professional blinded to patient\u0026rsquo;s clinical profile.\u0026nbsp;American Heart Association, American College of cardiology, and Society of Nuclear Medicine have defined the standards for plane selection and display orientation for serial myocardial slices generated by SPECT imaging with respective nomenclature i.e. short, vertical long, and horizontal long\u0026nbsp;axes\u003csup\u003e24\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eScoring left ventricular myocardial perfusion during rest using 17 segments:\u003c/strong\u003e For the semi-quantitative evaluation of left ventricular perfusion, Sum rest score (SRS) is used to calculate the perfusion score considering both the extent and severity of ischemia in relation to the 17 segments of the polar map. Normal perfusion (as compared with averaged gender-specific data from the population of healthy individuals) is indicated on the scale as a score of 0 (normal perfusion in relation to the control group). Mild and moderate perfusion impairment is indicated by 1 and 2 points, respectively. A score of 3 points indicates significant perfusion impairment, while a score of 4 points is used to indicate total impairment, meaning practically no perfusion. It is estimated that a left ventricular perfusion deficit with a score of 1 or 2 indicates that isotopic activity in this segment is approximately 60% in comparison to the area of radiotracer accumulation specified as 100%. Three points indicate radiotracer activity between 40% and 60%, while 4 points indicate radiotracer activity below 40% in relation to the area with 100% activity respectively.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAssessment of AAR by SPECT\u003c/strong\u003e: After initial myocardial uptake, subsequent 99mTc-Sestamibi clearance is slow without redistribution once bound to viable myocardium\u003csup\u003e25\u003c/sup\u003e. Hence, any myocardial perfusion study will reflect perfusion at the time of tracer injection. Therefore, it is possible to assess AAR by tracer injection before coronary intervention.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAssessment of FIS by SPECT\u003c/strong\u003e: Assessment of FIS by 99mTc-Sestamibi SPECT requires repeated imaging in a stable post-infarction state. FIS imaging must be postponed at least 120 h as assessment of 99mTc-Sestamibi uptake performed at 48\u0026ndash;72 h overestimates FIS. A further reduction in infarct size can be seen during the following days to weeks\u003csup\u003e26\u003c/sup\u003e. Optimal timing is better after several weeks. FIS measured by 99mTc-Sestamibi SPECT is consistent with histopathological estimates\u003csup\u003e27, 28\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAdwAAABKCAYAAAAR6+UfAAATYklEQVR4Ae2ci5EktRJF1wVswAV8wARswAU8wAM8wAIswAEcwAN82BeHiAP5klT9+rM9vVcRHaoqKX9XUl6pumc+fU4JAkEgCASBIBAEHo7Ap4dbiIEgEASCQBAIAkHgcwg3kyAIBIEgEASCwBMQCOE+AeSYCAJBIAgEgSAQws0cCAJBIAgEgSDwBARCuE8AOSaCQBAIAkEgCIRwMweCQBAIAkEgCDwBgRDuE0COiSAQBIJAEAgCIdzMgSAQBIJAEAgCT0AghPsEkGMiCASBIBAEgkAIN3MgCASBIBAEgsATEAjhPgHkmAgCQSAIBIEgEMLNHAgCQSAIvDgCP//88+dPnz59pj5Tfv/997/lvv/++6XYjz/++Hcf9PcPcr/99ttS9lkNf/755398675O+Pz666//J/fNN9+MLhPjDz/88H99v/vuu88//fTT2P/qwxDuVeQiFwSCQBB4AgJ//fXXZ4hiIpQ98xAmcluEiw7IhX6//PLLPyr/+OOPf56/AuniAz5OpInftLHB6AXSVA7i7sUNB5sZsKagBzvffvtt737TfQj3JvgiHASCQBB4LAIQAokf0jhzwuV0p9we4UrMkGwtR07Itf8jr7d8sW2y79uB6bRKvOAKxr3wbHre+525D+GeQSt9g0AQCAJPRABC4KQlMfDa80jhpAbZQkTU06mw6pGY6zOuJbI9wu5yj7j39fCZTQd+QJqQ6nRKl4yntkfEEMJ9BKrRGQSCQBC4AwIQnQQDaRwlPmTsS43sqkDOK92S3FGiX9m4x3NfDbMJOFN8Xe7r4ior4U6n39rvXtfrUbiXhegJAkEgCASB0whw6uLkaVmRou3WfE/JidbvK/cI1+9GJXb1UEtWZ0mu6rjXtb5U4mRDsLUZcDOB7FQ8wYMtuh5dQriPRjj6g0AQCAInEYAoINv6qvMo4UJA9cS2R7jTyRG7yEHczyCiPXgkzroB8XX7tFFQn5uJre9iPeWCL9hVQlfPveoQ7r2QjJ4gEASCwJ0QgAQgvFogBD5bhRMbJFlJQ8JdnVI9OaqfGh0QsafkLZvPaJM4q49er+LCLzcTe5sG9BMzOsGj4nfP+LZH756WoisIBIEgEAR2EfCVcCcSCWZLAWTRT3x7hCvJqNcTX/0TIdu2au3o55G6+7rSP/kkCa9keK5PRzYO9HHzsXUi3rK31xbC3UMo7UEgCASBJyLgr2pXhLVyhVPcSobnncDRwzPaOsHwjBPfqxSJk9fIFnyHILfK2TggXWT4PKI8RusjPI3OIBAEgsCbIyABTicySWeCgFegEOT06tTT4US4tvXTrLYqwU12n/XsLHHil1hu/ahq8t9T7tR267MQ7q0IRj4IBIEgcCcEILp+2lS1JLgizvqDImWoJVXqXtTZifXod59d3yPuJU58PVOMu28m0EEbMU4lhDuhkmdBIAgEgTdCwFfCnfwMUXLshOtr0IlYkJV4JsL1h0LasEYXp8oVKdnvGbW+TP5v2edkSwwdL2TAcnodLZarTc+WvSNtOeEeQSl9gkAQCAIPRMBXwhDE9AtZiEBy7K+NJWJ+RNQLumzvJCKRYbO/wob0ec6pefKn23nUPbbxAV+6/1s29R+5jhdyYgkGxgd+kDAfn23ZuNIWwr2CWmSCQBAIAndCALKTVCAICLIXnvuBLDy1Saa0oaMTZ22nDwRD8Re+6qTuJCMpTXq7f4+69/Wufh45cROH/a3FSz/RAzbGSD/i5BTdcVDmHnUI9x4oRkcQCAJBIAgEgR0EQrg7AKU5CASBIBAEgsA9ELhMuH4hvTqyV+c4vtuv/kS7v+7o30EoY1111mve1/N+39cD1Njpr1eqjNe8PuA1Qn2lgzy+9dcQytSaPvhH/1XxxxDGUWtemax+DID/tW+9xp6vh1Z2a0zI7vVHD3iI40rv5Nfqhx4rHT5nzPtcApMjr47Q4RzaGqsjODAGFV+ua5lewdX21fUR/5R1LtbXaM7F6XuoHlf3n3vkj5QjY1rHadLrWtCPPq9X6wBd6O7rv/t9JV7iQr8+UVu6v1trWJnUQeAWBP6dfRe01MSwSub1y2sWTC20uRj64qSfSY4+q4RuoqwEy0LCFnIsuFXRPn1d7CQ9E4vPVvI8N6HuLVY3Hei24BsbBZLAimAqBsrhtz4yBvg8FZ6baFb6u5x41sTU+3CvX/Q7gtOkw9ixaQyMHePW58okXxMm16tyFAcxXc0bx3BrPlYfjvqHDGNKzH0uVoyqbq5rXH190Iafdb51+X5/ZEzrmp/GnTywNZ/FsPqFHvUS76pcjbeOQ8fJMd9aRyt/8jwInEXgJsKFZCSciTBxpvaZkr4JZdrBm/z7IjFIF/e0SN1NT23Io9PEzkKuxQXan9c+XGODBEmC2SNcY5k2JsjzmYq+1ARlP7FbxUg/de/FQl9POcaknanWLxLVlQL++Db5zrPpebcjQaEHf7bKERyMaTWWzreJaCbbR/3bmouSzGoNGNdknzim+Tb15Znxb40pOiWpaYxcd6uN7modEKekO+UCfb4a72pO8zxkK7qpH43AnOUPWmWyuiueCIGFA6mxMFko00JSvpMxCxDZVcIwYePDRCa2r5KHi3svUa+gwCa2kafG160iBpO9rSQiPtOGRoJEfiq2rzDoMowhdvR1leSR068+bl3n6t7Ei54rhXlB8jfBr+YJuhkrMNrDQcJZES7PV209hjP+ORe38O76a1xHfZp01GdiuTWme3OecaXPqqCbsZjWgfZX8TiOq/aVTZ5rt843nrFuV5uDLX1pCwJXEJgz9QFNJnPrvghYHExmFpEJZTWxWYB9kZL8JxLXNdqQQ/+q0M6nFxf2tEPvfVf3JBZjpp7sVFkxqM+4Fr8VYZsopgSFPLhhe2o/Q4rI4wPjJhlOOvVfv2oCs+1IrQ30nC3OLfzjQ/zoW5WjODgWjmvVp44jpHjGv1vmoj5dwbDG5vXemIoPtZuyPv5gt7WuVusAH9S/Wku3xOsGXN/Anfl+ZDzFJ3UQuBWB/7LRQY1MfkmCpN8Jk8Vr4mIB2XdSL3my4CicDliYJK6puDAliKmPiXiy66LfIpRJp8+wj1793SNc4gAD8VAPtUluRRjqXmFh+xSLuntSrPa9BhM3L5LhpNP+2hUDnx+tHR9w0e5RWeIycapnhR86jeeIndU4Mb+xe6Sc8e+WuTjF5do44mfvoy+ruVbXvOTnOKgL/LbeNtCOnVWhnc9Ubo0Xu6xbSJb6yHyY/MizIHAVgXlmH9BGUpFATL6KuZukNiFunVZZoCwyFgAyJDfqVbF/X+y1v3b10TYT0kTE9tmriaUm3x5/lzc5VVIgPvwn7qqry9K+laBMksTbi217pOgGR3kT26TTPvjVN1m2Ha21gy4wXSX6qg/c6mbHca7Y1v5cOz57ONAXX/rcQDfP7u2fc/EqjsblWsE/cOxzvuMx3SO7N6Z1zaMDTCpW+IEO/el2HKvVfNcHdEzl1njNG+jfmi+TbZ/pAzqOfq7a0mbq90FgntkH4iOZO5FYQEw+ExqT0kXlJLfvpNrEQ7JA797Ok37Y2+qHPfroh3b1Z4us7TvVJI2efF2EK4ISn75A8WElg20T1Jav6hR7fTZ57SVz+hFP9UPsVmOmX4zDrcVTE3Ew9vizVcC6+qUvPF8VdFdiWPXjuXjaR3y25pp9qc/4d+tc1Nde9zlf/Vtduyncmmt1zaOHvthGlmI8KxvOqxWWjuVqzvY4vT8arzGu9K/8zvMgcC8ELhGuydwk7ULinsVUCUlytO/KcRYBC2hrwStr39VOmn4kh5oMlDVJ1KRt25G6Jx1k9gjXdsnExLJHWOJKIpuKJ4opgWhjD0+SVScr7a4wsn3l1+Tr1jM2C47Xlr+Sszii0zh7DNqzfQ9r+zN3mTcW/Fnpto/1Wf+cix1HN6ASCjVx1GJc1bezm4OqzzFdkWFf88hKYI7ZHlb4SiyrdSthq6/6d2u8+M86MXf0DWq19SWu61jn+vjbg2dhda858W9mOaHRyW/ic+FJtnXROsH31Jtw1bnVX5BXfUxYlfjt66LvCcz2rZq4tD3VK5307aSoH6vkgx9uVlZ9PDlPCcoE2pN5jU+cplh4tiJc/VrFW20cva6+rGScS5O/lXiqvEl8FUvty7XjwrUbmqNxnvVPW5N+1xSxTu2ruNC5mi891nqvLytZfMCXvj5ZY3woxL+Fc+1bbXttDqj5w7Zb40U360Rct9aFNlMHgXsjcIlwWVRMYIuLkQXFwrWYRGtf22rNImYx7/VTxoTrfa/xjz4TEZlYpiTW9dR7fCS+KRlob9IpNv2EpczWwscecUxFf2gH516Mc5VA6U+fCSN9xsepbPk19T/6jPFfxYsvfdOiXmTqvPM59dnNgbghu8Kn6vf6in/a2po3qzVxNi79XNVgyLiuCvFNvjB/kHXOQGhTcfOyGiflV2N8S7z4iO9uFvB3ZWfyvT5zzNBx9LNaR1Vvrr8OBOZsvhN7T0QSJhOwJnh3k3vfsRztp1tOdO9rDfmQOPhsEdGU5NwguDCr3q2EShs+TQvLtk6sxjwRHnb1ZZWgPN2usMWfrQRqgpswsm2yveWXm4BJp1iCx8rnFeGqd9rsoHdrPpBYaZ8K8XWdPKM/4wN+01zouq76p61pLuIXfqywMq7JPzCexq777b3j3TeFtlOjb5qrzmPHbvIHeeOZ1gjtyqNvKlfjxS7jWPOS5F2fTTbzLAjcG4E5E+1YIRH0hTMlB0mhk01X7y65J7/ez3sXzJSoXLgrXfiCr5NP6J12vpLMJINPYDFhQtvKV3f8+DsVE9SUcG1byap7K+kSJ75NxQQ8yWt78gscJvyqDXROfovxlNR5trV5AHs+vahzsmeMfXPgeGFvNd7dzlX/9uYiMU0EtBWX5N/XZ/e53uvHlsxqfqMHrGjfGnvX+BSPbdOcQv/VeB3jPo7OYeymBIFnIvDfLLVj3cW5WhyKs0hciFsLufbrC0NdvYZQ0E0iRZ7C4uKehc+CWhUTEvLIUNDhop9Ihmer5Ic+2/sClvhWPokP/XrRn5qguJYQaF+dJuwDHlMfxgOfVmPIc9qnBDr5he/Oi45Bj8uY6a9vxIWvk78mTdqmgiy+8nEu2M/E2uNEJ35M8YnNyp66rW/xj/jxg49zkWf6MMWEXePqWBO/c1F9+rmqsQcO2Or6lHFsO462OydW8vTThmNOTRzgjO2ttX8lXnMEuntxzMBdf3qf3AeBRyDw39m4YaUmt71FQnv9sGh6YbLXPlxvkXOVZ0FJLMixoFnwPelWGa/pU2WRZ+Ej3xOVCUwbXX9tp4+JY4oN/GrRBxZ+bTPBoa9+jLH7WHVKlsrhXy01mXe79Kvt6MBHy8ovbVHXOJSrNf7hE7aVIy7s9uSHrtqvzw0Tp3oYQ8eHtiprn1pPBGL8Wxgbzy3+qaPPRbEA64n0j8RFjEeLhCcuHWNitI3a+V31S4hTG/2c51UP19hmDByzqtPrK/H2ceHegi0w1pcJY/umDgL3RuD4yry35egLAkEgCASBl0aATbAb1zOOHpFj8+PGp9ceLvom/IwPr9g3hPuKoxKfgkAQCAIvgIBvfCDEM+WonG9QIHULJOvbtHd7A3EORRFJHQSCQBAIAm+NgCdQX8EfDfaMHF8ZQOb1qyvt+HXdka93lHn1OoT76iMU/4JAEAgCXwABSJCTqj+Km37cObl1Rs7v//tvB9Abwp3QzbMgEASCQBB4KwT8sRqvd309fOSkeVbOH3lOuj1ZHyX6jzAAOeF+hFGKj0EgCASBJyLAd6f+ZckZwj0rR//p+2G/2+1/ZfFECB5iKoT7EFijNAgEgSDwMRHof5J2lHDPynF6hmwrqfL9L/b4ERXP8yvljzmH4nUQCAJBIAjsIADBQXb1Fa+ES70qV+Q8xUK69QPRerpe2fuoz3PC/agjF7+DQBAIAndGwH9MU9UeIdwrcur1H5NwuuV7Wz7vdrIVzxCuSKQOAkEgCHzFCPjnPPW0Wa9XJ9yrcpxk0Y+8RRJe/dcy+33UOoT7UUcufgeBIBAE7ogABDj9P2xeL0OMK8K9KofO+g8vCEVb09/l3jHUL6YqhPvFoI/hIBAEgsBrICDR1dOmntkGsfZi21W5Tqy8SoaIea38jiWE+46jmpiCQBAIAicQgOA6+SkuqU6Ee1XOf904nZo59UK67/g9bgjXWZU6CASBIPAVIuD3pvzwaSr+c4p+6rwqB5GiC1KdXmFD/LS94/e4IdxphuVZEAgCQeArQEDShOA4WfqLYUOv7fTxFFyfn5FDr//sAn18OtF7+qUNO+9UQrjvNJqJJQgEgSAQBF4WgRDuyw5NHAsCQSAIBIF3QiCE+06jmViCQBAIAkHgZREI4b7s0MSxIBAEgkAQeCcEQrjvNJqJJQgEgSAQBF4WgRDuyw5NHAsCQSAIBIF3QiCE+06jmViCQBAIAkHgZREI4b7s0MSxIBAEgkAQeCcEQrjvNJqJJQgEgSAQBF4WgRDuyw5NHAsCQSAIBIF3QiCE+06jmViCQBAIAkHgZREI4b7s0MSxIBAEgkAQeCcEQrjvNJqJJQgEgSAQBF4WgRDuyw5NHAsCQSAIBIF3QiCE+06jmViCQBAIAkHgZRH4H+g9ihvZjWacAAAAAElFTkSuQmCC\" width=\"476\" height=\"74\"\u003e\u003c/p\u003e\n\u003cp\u003eA salvage index of \u0026lsquo;1\u0026rsquo; indicates complete revival of infarct area at risk, whereas a salvage index of \u0026lsquo;0\u0026rsquo; means no change in the infarct size despite revascularization.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEndpoints\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePrimary endpoints of our study were LV remodeling indices derived from 99mTc-Sestamibi scan viz area at risk [AAR], final infarct size [FIS], and myocardial salvage index at day 1and at 3 months of follow up respectively and secondary endpoints were the composite of cardiovascular death, recurrent MI, heart failure and stroke.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCategorical variables were presented as frequencies and percentages and compared using\u0026nbsp;\u0026chi;2 or Fisher exact test. Continuous variables were tested for normality, and differences were assessed using Student \u003cem\u003et\u0026nbsp;\u003c/em\u003etest or Mann-Whitney \u003cem\u003eU\u0026nbsp;\u003c/em\u003etest accordingly. Linear regression analyses between symptom onset to primary PCI as a continuous variable and myocardial salvage index, final infarct size, and LV function were performed. According to the duration of symptom onset to balloon time, patients were sub-classified into three cohorts i.e. cohort A [12-24 hrs.], cohort B [25-36 hrs.] and cohort C [37-48 hrs.] respectively. Association between late-presenting patients and the primary, as well as secondary endpoints, were adjusted for confounders by including any baseline variable with \u003cem\u003eP\u003c/em\u003e\u0026lt;0.1 for differences between the groups in multiple regression analyses. Furthermore, ANOVA test and post HOC analysis of cohorts were done to evaluate the effect of primary PCI and its timing on MSI. All analyses were performed using SPSS software. A \u003cem\u003eP\u0026nbsp;\u003c/em\u003evalue \u0026lt;0.05 was considered statistically significant for all analyses.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eBetween January 2020 and December 2023, a total of 264 late presenters were screened for enrollment, 195 patients were certified eligible to undergo SPECT followed by revascularization based on the inclusion criteria established. \u0026nbsp;Out of 195 patients 166 patients underwent SPECT Tc-99m sestaMIBI scan, who were then mobilized to cath lab for revascularization. Successful culprit artery revascularization was performed in 141 patients, while 18 patients were referred for coronary artery bypass grafting, 5 patients required multivessel PCI and 2 patients developed intraoperative coronary complications. As described previously, post Primary PCI subjects were sub-categorized into three cohorts (12 hours each) based on duration of symptom onset, Cohort wise baseline patient characteristic are shown in table 1 respectively. Out of 141 patients who underwent PCI for IRA, 35 patients required intra-coronary glycoprotein IIb/IIIa followed by a systemic infusion and none of the patients underwent thrombus aspiration as per institutional guidelines and operator discretion. PCI peri-procedural data are represented in table 2. Median duration of follow-up after primary PCI was 98 days (range), with 138 patients successfully completing the designed study (figure 1). \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOut of 141 patients who received primary PCI, only 17 patients underwent right femoral artery cannulation and remaining patients were treated with right radial artery access. Post IRA revascularization more than two third of patients belonging to cohort C (36-48 hours) failed to achieve TIMI III flow which could be hypothesized either to microvascular obstruction or non-viable myocardium. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA two way ANOVA analysis (table 3) determines a statistically significant difference in final LVEF achieved by patients who underwent primary PCI 12-24 hours (cohort A) of symptom onset. There was no statistically significant difference in AAR to the onset of symptoms across the cohorts (p =\u0026nbsp;0.3), however fall in MSI was concurrent with the delay in timing of PCI to symptom onset (figure 4). On post HOC analysis of cohorts, patients from cohort A achieved significantly higher MSI as compared to cohort B and C respectively\u0026nbsp;[Q = 4.18\u0026nbsp;(\u003cem\u003ep\u003c/em\u003e = .01025) and Q = 5.14 (\u003cem\u003ep\u003c/em\u003e = .00115)].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 1. Baseline patient characteristics subcategorized into cohorts based on duration of symptom onset to Primary PCI.\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"609\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003eCohort A\u003c/p\u003e\n \u003cp\u003e(n=83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003eCohort B\u003c/p\u003e\n \u003cp\u003e(n=37)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003eCohort C\u003c/p\u003e\n \u003cp\u003e(n=21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003eTest value (P Value)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eAge (Mean \u0026plusmn; SD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e60.93 \u0026plusmn; 12.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e60.81 \u0026plusmn; 10.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e57.14 \u0026plusmn; 10.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003e0.946 (0.391) NS\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eMale (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e68 (82%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e26 (70%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e17 (81%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003e2.15 (0.3412) NS\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eSmoker (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e43 (52%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e23 (62%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e11 (52%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003e1.156 (0.5610) NS\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eHypertension (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e25 (30%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e15 (41%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e02 (10%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003e6.173 (0.0456) *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eDiabetes mellitus (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e14 (17%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e17 (46%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e04 (19%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003e12.037 (0.00243) *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eDyslipidemia (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e13 (16%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e06 (16%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e06 (28%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003e1.993 (0.369) NS\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eFamily history of IHD (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e10 (12%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e02 (5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e05 (24%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003e4.279 (0.1177) NS\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eHeart rate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e86.64 \u0026plusmn; 13.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e78.03 \u0026plusmn; 10.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e77.43 \u0026plusmn; 13.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003e7.849 (\u0026lt;0.001) *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eSystolic BP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e140.02 \u0026plusmn; 25.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e139.84 \u0026plusmn; 21.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e143.52 \u0026plusmn; 25.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003e0.182 (0.834) NS\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eDiastolic BP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e88.92 \u0026plusmn; 13.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e87.78 \u0026plusmn; 12.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e93.81 \u0026plusmn; 14.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003e1.504 (0.226) NS\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eKillip class \u0026ndash; I (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e71 (85.50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e23 (62.10%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e08 (38%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e21.453 (0.000021) *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.35564853556485%\" valign=\"top\"\u003e\n \u003cp\u003eKillip class - II (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e12 (14.50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e14 (37.90%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e13 (62%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\" colspan=\"5\" valign=\"top\"\u003e\n \u003cp\u003eInfarct localization on Electrocardiogram (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eNew onset LBBB\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e02 (2.40%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e01 (2.70%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e01 (4.80%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" rowspan=\"5\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e12.609 (0.12602) NS\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.35564853556485%\" valign=\"top\"\u003e\n \u003cp\u003eAnterior\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e47 (56.60%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e22 (59.50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e18 (85.70%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.35564853556485%\" valign=\"top\"\u003e\n \u003cp\u003ePosterior\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e06 (7.20%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e02 (5.40%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.35564853556485%\" valign=\"top\"\u003e\n \u003cp\u003eInferior\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e34 (40.90%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e14 (37.80%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e02 (9.50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.35564853556485%\" valign=\"top\"\u003e\n \u003cp\u003eLateral\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e02 (2.40%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e03 (8.10%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.548117154811717%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\" colspan=\"5\" valign=\"top\"\u003e\n \u003cp\u003e2D Echocardiogram (M-mode)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eLVEF Day 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e36.02 \u0026plusmn; 6.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e35.54 \u0026plusmn; 9.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e35.85 \u0026plusmn; 7.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003e0.951 NS\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.750410509031198%\" valign=\"top\"\u003e\n \u003cp\u003eFinal LVEF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e48.25 \u0026plusmn; 9.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e39.75 \u0026plusmn; 10.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.912972085385878%\" valign=\"top\"\u003e\n \u003cp\u003e37.95 \u0026plusmn; 10.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.510673234811165%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026lt;0.0001 *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eTable 2. Peri-procedural cohort wise data undergoing primary PCI post SPECT Tc-99m sestaMIBI scan (day 1).\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"522\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.804597701149426%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.17624521072797%\" valign=\"top\"\u003e\n \u003cp\u003eCohort A\u003c/p\u003e\n \u003cp\u003e(n=83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.32567049808429%\" valign=\"top\"\u003e\n \u003cp\u003eCohort B\u003c/p\u003e\n \u003cp\u003e(n=37)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.32567049808429%\" valign=\"top\"\u003e\n \u003cp\u003eCohort C\u003c/p\u003e\n \u003cp\u003e(n=21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.367816091954023%\" valign=\"top\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\" colspan=\"5\" valign=\"top\"\u003e\n \u003cp\u003eLocation of infarct related lesion\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.804597701149426%\" valign=\"top\"\u003e\n \u003cp\u003eLeft main\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.17624521072797%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.32567049808429%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.32567049808429%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.367816091954023%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.804597701149426%\" valign=\"top\"\u003e\n \u003cp\u003eLeft anterior descending\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.17624521072797%\" valign=\"top\"\u003e\n \u003cp\u003e57 (68.70%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.32567049808429%\" valign=\"top\"\u003e\n \u003cp\u003e26 (70%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.32567049808429%\" valign=\"top\"\u003e\n \u003cp\u003e19 (90.50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.367816091954023%\" rowspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003e9.883 (0.0424) *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"47.651006711409394%\" valign=\"top\"\u003e\n \u003cp\u003eLeft circumflex\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.55480984340045%\" valign=\"top\"\u003e\n \u003cp\u003e08 (9.60%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e08 (21.60%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e02 (9.50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"47.651006711409394%\" valign=\"top\"\u003e\n \u003cp\u003eRight coronary\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.55480984340045%\" valign=\"top\"\u003e\n \u003cp\u003e23 (27.70%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e09 (24.30%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\" colspan=\"5\" valign=\"top\"\u003e\n \u003cp\u003ePre-PCI TIMI flow\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.804597701149426%\" valign=\"top\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.17624521072797%\" valign=\"top\"\u003e\n \u003cp\u003e66 (79.50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.32567049808429%\" valign=\"top\"\u003e\n \u003cp\u003e24 (64.90%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.32567049808429%\" valign=\"top\"\u003e\n \u003cp\u003e20 (95%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.367816091954023%\" rowspan=\"4\" valign=\"top\"\u003e\n \u003cp\u003e10.112 (0.0385) *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"47.651006711409394%\" valign=\"top\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.55480984340045%\" valign=\"top\"\u003e\n \u003cp\u003e16 (19.30%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e10 (27%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e01 (5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"47.651006711409394%\" valign=\"top\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.55480984340045%\" valign=\"top\"\u003e\n \u003cp\u003e01 (1.20%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e03 (8.10%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"47.651006711409394%\" valign=\"top\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.55480984340045%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\" colspan=\"5\" valign=\"top\"\u003e\n \u003cp\u003ePost-PCI TIMI flow\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.804597701149426%\" valign=\"top\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.17624521072797%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.32567049808429%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.32567049808429%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.367816091954023%\" rowspan=\"4\" valign=\"top\"\u003e\n \u003cp\u003e18.384 (0.0001) *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"47.651006711409394%\" valign=\"top\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.55480984340045%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e00 (00)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"47.651006711409394%\" valign=\"top\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.55480984340045%\" valign=\"top\"\u003e\n \u003cp\u003e07 (8.50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e01 (2.70%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e08 (38%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"47.651006711409394%\" valign=\"top\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.55480984340045%\" valign=\"top\"\u003e\n \u003cp\u003e76 (91.50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e36 (97.30%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.89709172259508%\" valign=\"top\"\u003e\n \u003cp\u003e13 (62%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 3. Cohort wise data of LV indices derived from SPECT Tc-99m sestaMIBI scan\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"654\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"28.593272171253822%\" valign=\"top\"\u003e\n \u003cp\u003eSPECT Tc-99m sestaMIBI parameters\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.654434250764528%\" valign=\"top\"\u003e\n \u003cp\u003eCohort A\u003c/p\u003e\n \u003cp\u003e(n=83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.571865443425075%\" valign=\"top\"\u003e\n \u003cp\u003eCohort B\u003c/p\u003e\n \u003cp\u003e(n=37)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.04281345565749%\" valign=\"top\"\u003e\n \u003cp\u003eCohort C\u003c/p\u003e\n \u003cp\u003e(n=21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.137614678899082%\" valign=\"top\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"28.593272171253822%\" valign=\"top\"\u003e\n \u003cp\u003eArea at risk\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.654434250764528%\" valign=\"top\"\u003e\n \u003cp\u003e35.44 \u0026plusmn; 12.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.571865443425075%\" valign=\"top\"\u003e\n \u003cp\u003e31.90 \u0026plusmn; 10.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.04281345565749%\" valign=\"top\"\u003e\n \u003cp\u003e35.14 \u0026plusmn; 9.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.137614678899082%\" valign=\"top\"\u003e\n \u003cp\u003e0.300 NS\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"28.593272171253822%\" valign=\"top\"\u003e\n \u003cp\u003eFinal Infarct size\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.654434250764528%\" valign=\"top\"\u003e\n \u003cp\u003e16.39 \u0026plusmn; 9.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.571865443425075%\" valign=\"top\"\u003e\n \u003cp\u003e19.36 \u0026plusmn; 7.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.04281345565749%\" valign=\"top\"\u003e\n \u003cp\u003e24.19 \u0026plusmn; 11.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.137614678899082%\" valign=\"top\"\u003e\n \u003cp\u003e0.0043 *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"28.593272171253822%\" valign=\"top\"\u003e\n \u003cp\u003eMyocardial salvage index\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.654434250764528%\" valign=\"top\"\u003e\n \u003cp\u003e0.53 \u0026plusmn; 0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.571865443425075%\" valign=\"top\"\u003e\n \u003cp\u003e0.38 \u0026plusmn; 0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.04281345565749%\" valign=\"top\"\u003e\n \u003cp\u003e0.34 \u0026plusmn; 0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.137614678899082%\" valign=\"top\"\u003e\n \u003cp\u003e0.00006 *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAlthough the AAR was comparable throughout cohorts, on post HOC analysis a statistically significant reduction in the final infarct size was seen among patients in cohort A vs C [Q = 4.72\u0026nbsp;(\u003cem\u003ep\u003c/em\u003e = .00309)], while a reduction of FIS in cohort B and cohort C were obvious but statistically insignificant (table 4). Myocardial salvage index was smaller in late presenters, with no statistically significant difference among cohort B \u0026amp; cohort C [Q = 0.96 (\u003cem\u003ep\u003c/em\u003e = .77697)]. A substantial salvage index (i.e. MSI \u0026gt;0.5) was achieved among 59 % of patients in cohort A and in not more than 35 % of patients in cohort B and C respectively. Timing of Primary PCI did not have a positive impact on MSI in patients presenting 24-48 hours of symptom onset [table 5].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 4: Post HOC analysis of FIS among cohorts.\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"515\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.46511627906977%\" colspan=\"2\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cem\u003ePairwise Comparisons\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.325581395348838%\"\u003e\n \u003cp\u003eHSD\u003csub\u003e.05\u003c/sub\u003e = 5.5339\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"37.2093023255814%\" rowspan=\"2\"\u003e\n \u003cp\u003eQ\u003csub\u003e.05\u003c/sub\u003e = 3.3515 \u0026nbsp; \u0026nbsp;Q\u003csub\u003e.01\u003c/sub\u003e = 4.1910\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\"\u003e\n \u003cp\u003eHSD\u003csub\u003e.01\u003c/sub\u003e = 6.9200\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.310077519379846%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eT\u003csub\u003e1\u003c/sub\u003e:T\u003csub\u003e2\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.155038759689923%\"\u003e\n \u003cp\u003eM\u003csub\u003e1\u003c/sub\u003e = 16.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.325581395348838%\" rowspan=\"2\"\u003e\n \u003cp\u003e2.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"37.2093023255814%\" rowspan=\"2\"\u003e\n \u003cp\u003eQ = 1.80 (\u003cem\u003ep\u003c/em\u003e = .41359)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\"\u003e\n \u003cp\u003eM\u003csub\u003e2\u003c/sub\u003e = 19.36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.310077519379846%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eT\u003csub\u003e1\u003c/sub\u003e:T\u003csub\u003e3\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.155038759689923%\"\u003e\n \u003cp\u003eM\u003csub\u003e1\u003c/sub\u003e = 16.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.325581395348838%\" rowspan=\"2\"\u003e\n \u003cp\u003e7.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"37.2093023255814%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cspan style=\"color: rgb(41, 105, 176);\"\u003e\u003cstrong\u003eQ = 4.72\u003c/strong\u003e\u003c/span\u003e (\u003cem\u003ep\u003c/em\u003e = .00309)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\"\u003e\n \u003cp\u003eM\u003csub\u003e3\u003c/sub\u003e = 24.19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.310077519379846%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eT\u003csub\u003e2\u003c/sub\u003e:T\u003csub\u003e3\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.155038759689923%\"\u003e\n \u003cp\u003eM\u003csub\u003e2\u003c/sub\u003e = 19.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.325581395348838%\" rowspan=\"2\"\u003e\n \u003cp\u003e4.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"37.2093023255814%\" rowspan=\"2\"\u003e\n \u003cp\u003eQ = 2.93 (\u003cem\u003ep\u003c/em\u003e = .10034)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\"\u003e\n \u003cp\u003eM\u003csub\u003e3\u003c/sub\u003e = 24.19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 5: Post HOC analysis of MSI among cohorts.\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"519\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"36.41618497109827%\" colspan=\"2\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cem\u003ePairwise Comparisons\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.433526011560694%\"\u003e\n \u003cp\u003eHSD\u003csub\u003e.05\u003c/sub\u003e = 0.1228\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.15028901734104%\" rowspan=\"2\"\u003e\n \u003cp\u003eQ\u003csub\u003e.05\u003c/sub\u003e = 3.3515 \u0026nbsp; \u0026nbsp;Q\u003csub\u003e.01\u003c/sub\u003e = 4.1910\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\"\u003e\n \u003cp\u003eHSD\u003csub\u003e.01\u003c/sub\u003e = 0.1535\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.221579961464354%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eT\u003csub\u003e1\u003c/sub\u003e:T\u003csub\u003e2\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.19460500963391%\"\u003e\n \u003cp\u003eM\u003csub\u003e1\u003c/sub\u003e = 0.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.433526011560694%\" rowspan=\"2\"\u003e\n \u003cp\u003e0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.15028901734104%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cspan style=\"color: rgb(44, 130, 201);\"\u003eQ = 4.18\u003c/span\u003e\u003c/strong\u003e (\u003cem\u003ep\u003c/em\u003e = .01025)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\"\u003e\n \u003cp\u003eM\u003csub\u003e2\u003c/sub\u003e = 0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.221579961464354%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eT\u003csub\u003e1\u003c/sub\u003e:T\u003csub\u003e3\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.19460500963391%\"\u003e\n \u003cp\u003eM\u003csub\u003e1\u003c/sub\u003e = 0.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.433526011560694%\" rowspan=\"2\"\u003e\n \u003cp\u003e0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.15028901734104%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cspan style=\"color: rgb(44, 130, 201);\"\u003eQ = 5.14\u003c/span\u003e\u003c/strong\u003e (\u003cem\u003ep\u003c/em\u003e = .00115)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\"\u003e\n \u003cp\u003eM\u003csub\u003e3\u003c/sub\u003e = 0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.221579961464354%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eT\u003csub\u003e2\u003c/sub\u003e:T\u003csub\u003e3\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"21.19460500963391%\"\u003e\n \u003cp\u003eM\u003csub\u003e2\u003c/sub\u003e = 0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.433526011560694%\" rowspan=\"2\"\u003e\n \u003cp\u003e0.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.15028901734104%\" rowspan=\"2\"\u003e\n \u003cp\u003eQ = 0.96 (\u003cem\u003ep\u003c/em\u003e = .77697)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\"\u003e\n \u003cp\u003eM\u003csub\u003e3\u003c/sub\u003e = 0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eThroughout the study cohorts, delaying the duration of performing Primary PCI from symptom onset was associated with larger AAR \u0026amp; FIS although with a lower correlation coefficient (figure 2). While evaluation MSI against timing of Primary PCI, a moderately negative (R= -0.41) relation exists between these two variables which is indicative of patients who underwent late PCI had a linear correlation with reduced myocardial salvage Index (figure 3b and 4).\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eOptimal treatment for patients who have acute myocardial infarction with ST-segment elevation includes early reperfusion with primary percutaneous coronary intervention (PCI) or thrombolytic therapy. However, approximately one third of eligible patients do not receive early reperfusion therapy, in many cases because of late presentation. Evidence on behavior and the fate of myocardium, after revascularization in asymptomatic STEMI patients presenting beyond 12 hours is scarce. \u003c/p\u003e\n\u003cp\u003eTo study the efficacy of Primary PCI in patients presenting 12-48 hours of symptom onset, we enrolled 141 patients for Tc-99m sestaMIBI scan followed by IRA revascularization and sub categorized them based on the timing of Primary PCI to symptom onset, into three cohorts of 12 hours each. 138 patients completed the designed study with a follow up Tc-99m sestaMIBI scan. We found that duration of symptom onset did not affect the initial LVEF and AAR throughout the cohorts. Despite having a comparable AAR, cohorts B and C had larger FIS and poorer MSI. Also, patients from Cohort A achieved higher final LVEF compared to rest of the subjects. \u003c/p\u003e\n\u003cp\u003eAs our study enrolled stable STEMI patients, unstable patients were systemically excluded from based on vitals and killip\u0026rsquo;s class at presentation. The mean pulse of the patients enrolled was 86/min with a mean SBP of 140 (\u0026plusmn; 25.98) mmHg and mean DBP 89(\u0026plusmn; 13.20) mmHg. 27 % of patients were in Killip\u0026rsquo;s class II at presentation and rest of the 102 individuals were in Killip\u0026rsquo;s class I. \u003cstrong\u003eAlbert Sch\u0026ouml;mig et al\u003csup\u003e29\u003c/sup\u003e \u003c/strong\u003ein BRAVE II also excluded patients in killip\u0026rsquo;s class III and IV, enrolling 81 % of patients in Killip\u0026rsquo;s class I and 19 % of patients in Killip\u0026rsquo;s class II, their patients had an mean pulse of 72/min, mean SBP of 140 mmHg and a mean DBP of 80 mmHg. \u003cstrong\u003eDoo Sun Sim et al\u003c/strong\u003e\u003csup\u003e30 \u003c/sup\u003ein their study found that, 83 % of patients were in Killip\u0026rsquo;s class I and 17 % of patients were in Killip\u0026rsquo;s class II. \u003cstrong\u003eJames E Udelson et al\u003csup\u003e31 \u003c/sup\u003e\u003c/strong\u003ein OAT-NUC trial had 82 % patients in killip\u0026rsquo;s class I and 18 % of patients in killip\u0026rsquo;s class II-IV. Hyperdynamic apex was observed in few patients with anemia, none of them had pericardial rub or a murmur.\u003c/p\u003e\n\u003cp\u003eAmong the patients who presented with STEMI, 62% of patients suffered an anterior wall MI followed by inferior wall MI (25 %), and few individuals suffered infarction of posterior wall (9%) associated with IWMI. Patients from cohort C predominantly suffered anterior wall infarction and achieved an overall smaller MSI. On coronary angiogram, 63 % had occlusion of single vessel involving left anterior descending, 18 % patients involving right coronary artery and 8.5 % patients involving circumflex artery respectively. 14 (9.9 %) individuals had double vessel disease who\u0026rsquo;s SYNTAX score were \u0026lt; 22.\u003cstrong\u003e Albert Sch\u0026ouml;mig et al\u003csup\u003e29\u003c/sup\u003e \u003c/strong\u003ein BRAVE II found that 63 % of individuals had AWMI and 35 % had IWMI subsequently 37 % of patients had a lesion in LAD, 31 % in RCA and 29 % in LCX. All of our patients underwent PTCA + stenting of IRA with 3\u003csup\u003erd\u003c/sup\u003e generation DES. TIMI III flow was achieved in 88 % of our patients in comparison to 87 % in BRAVE II trial. Echocardiographic assessment at presentation showed that Initial mean LV function was 35.87 %( \u0026plusmn;7.61) and final mean LVEF mean follow up of 98 days was 44.54 % (\u0026plusmn;10.87) figure. A statistically significant difference (P=\u0026lt;0.0001), was noted in final LVEF in total cohorts. \u003cstrong\u003eLars Nepper-Christensen et al\u003csup\u003e32\u003c/sup\u003e\u003c/strong\u003e found that in his patients initial mean LVEF was 45 % and final LVEF was 51 % which was statistically significant. \u003cstrong\u003eShoichi Miyamoto et al\u003csup\u003e33\u003c/sup\u003e \u003c/strong\u003ehad also found a statistically significant difference in initial (48%) and chronic LVEF (51 %). \u003c/p\u003e\n\u003cp\u003eAll of the patients underwent Tc99m-sestaMIBI scan prior to revascularization, area at risk at day 1 and final infarct size at follow up is expressed as % of infarct size, mean AAR was 34.47 %(\u0026plusmn;11.70) and mean final infarct size was 18.29% (\u0026plusmn;9.85), with a mean MSI of 0.46 (\u0026plusmn; 0.22) in overall cohorts. \u003cstrong\u003eLars Nepper-Christensen et al\u003csup\u003e32\u003c/sup\u003e \u003c/strong\u003estudied that AAR, FIS and MSI of patients enrolled in his study were 34 %, 13 % and 0.58 respectively. In total cohorts, an MSI of \u0026gt; 0.50 was attained among 36 %, 8% and 5 % of patients from cohort A, B, and C respectively (figure 5). We also found that age (primary event) did not have any statistical significance over myocardial salvage index.\u003c/p\u003e\n\u003cp\u003eMyocardial salvage and infarct size may in addition to duration of ischemia be affected by peri procedural events, such as distal embolization, no-reflow phenomenon, or lethal reperfusion injury. It could be speculated that the risk of distal embolization and no-reflow increases in late presenters as the thrombotic occlusion of the coronary artery consolidates over time\u003csup\u003e35\u003c/sup\u003e. \u003c/p\u003e\n\u003cp\u003eOn analysis of secondary endpoints among overall cohorts, 13 % of patients had recurrent heart failure hospitalization and 27 % of patients needed optimization of heart failure therapy as a result of worsening functional class (NYHA class \u0026ge; II). Aforementioned patients predominantly suffered an AWMI (65 %), with a mean final LVEF of 38.87 (\u0026plusmn;9.77) on follow up. The mean duration of Primary PCI to symptoms in these patients was 24.60 (\u0026plusmn;9.11) hours with a mean MSI of 0.31 (\u0026plusmn; 0.16). Although the final LVEF and FIS observed was statistically significant (p\u0026lt;0.05), it did not contribute clinically in improving functional class, which also solidifies our understanding of ischemic heart failure pathology being multifactorial. Also, in this group of patients mean AAR (33.82 (\u0026plusmn; 10.62)) was comparable to total cohort, however primary PCI did not exert a positive clinical impact (figure 6).\u003c/p\u003e\n\u003cp\u003eOn further analysis of secondary endpoints one patients suffered CV death, 2 patients suffered non hemorrhagic stroke and none of the patients had recurrent MI. In \u003cstrong\u003eBRAVE II\u003c/strong\u003e trial cumulative incidence of the composite of death, recurrent MI, or stroke was 4.9%.\u003cstrong\u003eDoo Sun Sim et al\u003c/strong\u003e\u003csup\u003e30\u003c/sup\u003e reported that 1.7 % of patients had MI/death at12 months.\u003cstrong\u003e Patrick W. McNair et al\u003c/strong\u003e \u003csup\u003e34\u003c/sup\u003e in their study found that 16 % of patients had heart failure, 4 % of patients died and 2 % of patients suffered stroke.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eAsymptomatic stable STEMI patients presenting 12\u0026ndash;24 hours of symptom onset to PCI had a significant benefit with primary PCI with a lesser final infarct size and a larger myocardial savage index. Despite a comparable AAR across the cohorts, MSI fell sharply in patients undergoing primary PCI 24\u0026ndash;48 hours of symptom onset with a larger final infarct size, warranting a viability guided revascularization. Although primary PCI improved final LVEF and MSI in patients who suffered ischemic heart failure, gain in parameters alone was insufficient in endeavoring a positive clinical impact on the course of ischemic heart failure, contemplating a multifactorial pathology.\u003c/p\u003e"},{"header":"Limitations","content":"\u003cp\u003eDespite having a large number of patients who qualified the enrollment criteria, our study population was smaller due to the restricted availability of nuclear material. Infarct size derived from Tc-99m sestaMIBI could possibly have an Observer bias as it is a semi-quantitative analysis with a feedback from reporter, also LVEF calculated at presentation and at follow up was reported by multiple observers and may carry a subjective inter-observer bias.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to thank Dr. R K Patel, Dr Jayesh Prajapati, Dr Tanmay Agarwal, Dr Mithilesh Kulkarni, Dr. Amita Goswami and the staff, Dept. of Nuclear Medicine, U N Mehta institute of Cardiology, Ahmedabad, Gujarat, India.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDisclosures\u003c/strong\u003e: - None\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e: - None\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAuthor M.P. and S.T. were primarily responsible for enrolling patients eligible for this study and as well as performing PCI in STEMI- late comersAuthor S.S. is a senior cardiologist and unit chief who made decisions on revascularization and technical aspectsAuthor V.P. is qualified nuclear medicine physician who was primary responsible to report TC-99m sestaMIBI scan reportsAuthor V.K. played role as a statistical expert and helped deriving complex post HOC analysisAurthor J.J. V.P. and P.S. made sure study is blinded, helped in coordination and adressed patient greviencesAll authors reviewed the manuscript\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eQian L, Ji KT, Nan JL, Lu Q, Zhu YJ, Wang LP et al (2013) Factors associated with decision time for patients with ST-segment elevation acute myocardial infarction. J Zhejiang Univ Sci 14(8):754\u0026ndash;758\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePiegas LS, Feitosa G, Mattos LA, Nicolau Jc, Rossi Neto JM, Timerman A et al (2009) ;Sociedade Brasileira de Cardiologia. IV Diretrizes da SBC sobre tratamento do infarto agudo do mioc\u0026aacute;rdio com supradesn\u0026iacute;vel do segmento ST. Arq Bras Cardiol 93(6 supl 2):e179\u0026ndash;e264\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eReimer KA, Jennings RB (1979) The wavefront phenomenon of myocardial ischemic cell death. II. Transmural progression of necrosis within the framework of ischemic bed size (myocardium at risk) and collateral flow. Lab Invest 40:633\u0026ndash;644\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGersh BJ, Stone GW, White HD, Holmes DR Jr. (2005) Pharmacological facilitation of primary percutaneous coronary intervention for acute myocardial infarction: is the slope of the curve the shape of the future? JAMA 293:979\u0026ndash;986. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1001/jama.293.8.979\u003c/span\u003e\u003cspan address=\"10.1001/jama.293.8.979\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIbanez B, James S, Agewall S, Antunes MJ, Bucciarelli-Ducci C, Bueno H, Caforio ALP, Crea F, Goudevenos JA, Halvorsen S, Hindricks G, Kastrati A, Lenzen MJ, Prescott E, Roffi M, Valgimigli M, Varenhorst C, Vranckx P, Widimsk\u0026yacute; P, ESC Scientific Document Group (2018) 2017 ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation: the Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC). Eur Heart J 39:119\u0026ndash;177. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1093/eurheartj/ehx393\u003c/span\u003e\u003cspan address=\"10.1093/eurheartj/ehx393\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eO\u0026rsquo;Gara PT, Kushner FG, Ascheim DD, Casey DE, Chung MK, de Lemos JA, Ettinger SM, Fang JC, Fesmire FM, Franklin BA, Granger CB, Krumholz HM, Linderbaum JA, Morrow DA, Newby LK, Ornato JP, Ou N, Radford MJ, Tamis-Holland JE, Tommaso CL, Tracy CM, Woo YJ, Zhao DX (2013) 2013 ACCF/AHA Guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation 127:e362\u0026ndash;e425. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1161/CIR.0b013e3182742cf6\u003c/span\u003e\u003cspan address=\"10.1161/CIR.0b013e3182742cf6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSch\u0026ouml;mig A, Ndrepepa G, Kastrati A (2006) Late myocardial salvage: time to recognize its reality in the reperfusion therapy of acute myocardial infarction. Eur Heart J 27:1900\u0026ndash;1907. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1093/eurheartj/ehl174\u003c/span\u003e\u003cspan address=\"10.1093/eurheartj/ehl174\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEagle KA, Nallamothu BK, Mehta RH et al (2008) Trends in acute reperfusion therapy for ST-segment elevation myocardial infarction from 1999 to 2006: we are getting better but we have got a long way to go. Eur Heart J 29:609\u0026ndash;617\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCohen M, Gensini GF, Maritz F et al (2003) TETAMI Investigators - Prospective evaluation of clinical outcomes after acute ST-segment elevation myocardial infarction in patients who are ineligible for reperfusion therapy: preliminary results from the TETAMI registry and randomized trial. Circulation 3:14\u0026ndash;21\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbbate A, Bussani R, Biondi-Zoccai GG et al (2002) Persistent infarct related artery occlusion is associated with an increased myocardial apoptosis at postmortem examination in humans late after an acute myocardial infarction. Circulation 106:1051\u0026ndash;1054\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbbate A, Bussani R, Biondi-Zoccai GG et al (2005) Infarct-related artery occlusion, tissue markers of ischaemia, and increased apoptosis in the peri-infarct viable myocardium. Eur Heart J 26:2039\u0026ndash;2045\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSabia PJ, Powers ER, Ragosta M, Sarembock U, Burwell LR, Kaul S (1992) An association between collateral blood flow and myocardial viability in patients with recent myocardial infarction. N Engl J Med 327:1825\u0026ndash;1831\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrunken R, Tillisch J, Schwaiger M et al (1986) Regional perfusion, glucose metabolism, and wall motion in patients with chronic electrocardiographic Q wave infarctions: evidence of persistence of viable tissue in some infarct regions by positron emission tomography. Circulation 73:951\u0026ndash;963\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbbate A, Biondi-Zoccai GG, Appleton DL, Erne P, Schoenenberger AW, Lipinski MJ, Agostoni P, Sheiban I, Vetrovec GW (2008) Survival and cardiac remodeling benefits in patients undergoing late percutaneous coronary intervention of the infarct-related artery: evidence from a meta-analysis of randomized controlled trials. J Am Coll Cardiol 51:956\u0026ndash;964. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jacc.2007.11.062\u003c/span\u003e\u003cspan address=\"10.1016/j.jacc.2007.11.062\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIoannidis JP, Katritsis DG (2007) Percutaneous coronary intervention for late reperfusion after myocardial infarction in stable patients. Am Heart J 154:1065\u0026ndash;1071. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.ahj.2007.07.049\u003c/span\u003e\u003cspan address=\"10.1016/j.ahj.2007.07.049\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHochman JS, Lamas GA, Buller CE, Dzavik V, Reynolds HR, Abramsky SJ, Forman S, Ruzyllo W, Maggioni AP, White H, Sadowski Z, Carvalho AC, Rankin JM, Renkin JP, Steg PG, Mascette AM, Sopko G, Pfisterer J, Fridrich V, Mark DB, Knatterud GL (2006) Occluded Artery Trial Investigators. Coronary intervention for persistent occlusion after myocardial infarction. \u003cem\u003eN Engl J Med\u003c/em\u003e. ;355:2395\u0026ndash;2407. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1056/NEJMoa066139\u003c/span\u003e\u003cspan address=\"10.1056/NEJMoa066139\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGierlotka M, Gasior M, Wilczek K, Hawranek M, Szkodzinski J, Paczek P, Lekston A, Kalarus Z, Zembala M, Polonski L (2011) Reperfusion by primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction within 12 to 24 hours of the onset of symptoms (from a Prospective National Observational Study [PL-ACS]). Am J Cardiol 107:501\u0026ndash;508. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.amjcard.2010.10.008\u003c/span\u003e\u003cspan address=\"10.1016/j.amjcard.2010.10.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSch\u0026ouml;mig A, Mehilli J, Antoniucci D, Ndrepepa G, Markwardt C, Di Pede F, Nekolla SG, Schlotterbeck K, Sch\u0026uuml;hlen H, Pache J, Seyfarth M, Martinoff S, Benzer W, Schmitt C, Dirschinger J, Schwaiger M, Kastrati A (2005) Beyond 12 hours Reperfusion Alternative Evaluation (BRAVE-2) Trial Investigators. Mechanical reperfusion in patients with acute myocardial infarction presenting more than 12 hours from symptom onset: a randomized controlled trial. JAMA 293:2865\u0026ndash;2872. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1001/jama.293.23.2865\u003c/span\u003e\u003cspan address=\"10.1001/jama.293.23.2865\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBusk M, Kaltoft A, Nielsen SS, B\u0026oslash;ttcher M, Rehling M, Thuesen L, B\u0026oslash;tker HE, Lassen JF, Christiansen EH, Krusell LR, Andersen HR, Nielsen TT, Kristensen SD (2009) Infarct size and myocardial salvage after primary angioplasty in patients presenting with symptoms for \u0026lt;\u0026thinsp;12 h vs. 12\u0026ndash;72 h. Eur Heart J 30:1322\u0026ndash;1330. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1093/eurheartj/ehp113\u003c/span\u003e\u003cspan address=\"10.1093/eurheartj/ehp113\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStiermaier T, Eitel I, de Waha S, P\u0026ouml;ss J, Fuernau G, Thiele H, Desch S (2017) Myocardial salvage after primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction presenting early versus late after symptom onset. Int J Cardiovasc Imaging 33:1571\u0026ndash;1579. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s10554-017-1143-x\u003c/span\u003e\u003cspan address=\"10.1007/s10554-017-1143-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMonteiro P, Antunes A, Goncalves LM, Providencia LA (2003) Long-term clinical impact of coronary-collateral vessels after acute myocardial infarction. Rev Port Cardiol 22:1051\u0026ndash;1061\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSingh M, Rihal CS, Lennon RJ, Garratt KN, Mathew V, Holmes DR Jr (2005) Prediction of complications following nonemergency percutaneous coronary interventions. Am J Cardiol 96:907\u0026ndash;912\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003evan Hellemond IE, Bouwmeester S, Olson CW, Botker HE, Kaltoft AK, Nielsen SS et al (2011) Consideration of QRS complex in addition to ST-segment abnormalities in the estimated \u0026lsquo;risk region\u0026rsquo; during acute anterior myocardial infarction. J Electrocardiol 44:370\u0026ndash;376\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAmerican Heart Association (1992) American College of Cardiology, and Society of Nuclear Medicine. Standardization of cardiac tomographic imaging. Circulation 86:338\u0026ndash;339\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOkada RD, Williams SJ, Glover DK, Dragatokis D (1988) Cardiac imaging and myocardial kinetics of technetium-tertiary butyl-isonitrile during dipyridamole-induced hyperemia. Am Heart J 116:979\u0026ndash;988\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNdrepepa G, Mehilli J, Martinoff S, Schwaiger M, Schomig A, Kastrati A (2007) Evolution of left ventricular ejection fraction and its relationship to infarct size after acute myocardial infarction. J Am Coll Cardiol 50:149\u0026ndash;156\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMedrano R, Lowry RW, Young JB, Weilbaecher DG, Michael LH, Afridi I et al (1996) Assessment of Myocardial viability with 99mTc sestamibi in patients undergoing cardiac transplantation. A scintigraphic/pathological study. Circulation 94:1010\u0026ndash;1017\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKristensen J, Mortensen UM, Nielsen SS, Maeng M, Kaltoft A, Nielsen TT et al (2004) Myocardial perfusion imaging with Tc-99m sestamibi early after reperfusion reliably reflects infarct size reduction by ischaemic preconditioning in an experimental porcine model. Nucl Med Com 25:495\u0026ndash;500\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchomig A, Mehilli J, Antoniucci D et al (2005) Mechanical reperfusion in patients with acute myocardial infarction presenting more than 12 hours from symptom onset: a randomized controlled trial. JAMA 293:2865\u0026ndash;2872\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSim DS, Jeong MH, Ahn Y, Kim YJ, Chae SC, Hong TJ, Seong IW, Chae JK, Kim CJ, Cho MC, Rha SW, Bae JH, Seung KB (2012) Park, Korea Acute Myocardial Infarction Registry (KAMIR) Investigators Benefit of percutaneous coronary intervention in early latecomers with acute ST-segment elevation myocardial infarction. Am J Cardiol 110:1275\u0026ndash;1281\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUdelson JE, Pearte CA, Kimmelstiel CD, Kruk M, Kufera JA, Forman SA, Teresinska A, Bychowiec B, Marin-Neto JA, H\u0026ouml;chtl T, Cohen EA, Caramori P, Busz-Papiez B, Adlbrecht C, Sadowski ZP, Ruzyllo W, Kinan DJ, Lamas GA, Hochman JS (2011) The Occluded Artery Trial (OAT) Viability Ancillary Study (OAT-NUC): influence of infarct zone viability on left ventricular remodeling after percutaneous coronary intervention vs. optimal medical therapy alone. Am Heart J 161:611\u0026ndash;621\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNepper-Christensen L, L\u0026oslash;nborg J, H\u0026oslash;fsten DE, Ahtarovski KA, Bang LE, Helqvist S, Kyhl K, K\u0026oslash;ber L, Kelb\u0026aelig;k H, Vejlstrup N, Holmvang L, Engstr\u0026oslash;m T (2018) Benefit from reperfusion with primary percutaneous coronary intervention beyond 12 hours of symptom duration in patients with ST-segment\u0026ndash;elevation myocardial infarction. Circ Cardiovasc Interv 11:e006842. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1161/CIRCINTERVENTIONS.118.006842\u003c/span\u003e\u003cspan address=\"10.1161/CIRCINTERVENTIONS.118.006842\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMiyamoto S, Goto Y, Fujita M et al (2001) Late reperfusion (6\u0026ndash;24 hours after onset) improves left ventricular function in patients with acute myocardial infarction. Jpn Circ J 65:389\u0026ndash;394\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcNair PW, Bilchick KC, Keeley EC (2019) Very late presentation in ST elevation myocardial infarction: predictors and long-term mortality. Int J Cardiol Heart Vasc 22:156\u0026ndash;159\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eL\u0026oslash;nborg J, Engstr\u0026oslash;m T, Ahtarovski KA, Nepper-Christensen L, Helqvist S, Vejlstrup N, Kyhl K, Schoos MM, Ghotbi A, G\u0026ouml;ransson C, Bertelsen L, Holmvang L, Pedersen F, J\u0026oslash;rgensen E, Saunam\u0026auml;ki K, Clemmensen P, De Backer O, Kl\u0026oslash;vgaard L, H\u0026oslash;fsten DE, K\u0026oslash;ber L, Kelbak H (2017) DANAMI-3 Investigators. Myocardial damage in patients with deferred stenting after STEMI: a DANAMI-3-DEFER substudy. J Am Coll Cardiol 69:2794\u0026ndash;2804. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jacc.2017.03.601\u003c/span\u003e\u003cspan address=\"10.1016/j.jacc.2017.03.601\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"ST segment elevation MI, Percutaneous coronary intervention, Myocardial salvage index, TC-99m SestaMIBI scan, Late presenting myocardial infarction","lastPublishedDoi":"10.21203/rs.3.rs-4163687/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4163687/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e: Guidelines on revascularization of asymptomatic STEMI patients presenting 12-48 hours of symptom onset are limited, evidence contributing lack of symptoms to non-viable myocardium are scarce. We utilized TC-99mSestaMIBI scan to study the impact of primary PCI on myocardial viability by deriving myocardial salvage index (MSI) in asymptomatic STEMI patients presenting between 12-48 hours of symptom onset to PCI.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods and results\u003c/strong\u003e: We enrolled 141 patients with STEMI (12-48 hours), from January 2020 to December 2023, who then underwent TC-99mSestaMIBI scan, followed by revascularization of IRA with 138 patients completing the designed study with follow-up scan at 3 months. A substantial MSI of \u0026gt; 0.50 was achieved by 36 %, 8% and 5 % of patients from cohort A(12-24 hrs.), B(25-36 hrs.), and C(37-48 hrs.) respectively.Post Hoc analysis determined a comparable AAR of 34.47 %( ±11.70) throughout cohorts, however a greater reduction in FIS [Q=4.72 (p=.00309)]and MSI gain was noted among patients of cohort A alone [Q=4.18 (p=.01025)]. Regression analysis of MSI against PCI timing was negatively correlated (R= -0.41).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e:\u003cstrong\u003e \u003c/strong\u003eAsymptomatic stable STEMI patients presenting 12-24 hours of symptom onset to PCI, benefited from primary PCI with lesser final infarct size and larger MSI. Despite a comparable AAR across cohorts, MSI fell sharply among patients undergoing primary PCI 24-48 hours of symptom onset with a larger final infarct size, warranting viability guided revascularization. Although primary PCI improved final LVEF and MSI in patients with ischemic heart failure, parameter gain alone was insufficient in endeavoring a positive clinical impact.\u003c/p\u003e","manuscriptTitle":"Effect of Primary PCI in asymptomatic STEMI patients presenting 12-48 hours of symptom onset, on myocardial viability assessed on SPECT - ‘EPITOME-99’","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-29 17:51:10","doi":"10.21203/rs.3.rs-4163687/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"08f852c5-9db2-4731-91d4-861fc03e5364","owner":[],"postedDate":"March 29th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-12-24T09:38:56+00:00","versionOfRecord":[],"versionCreatedAt":"2024-03-29 17:51:10","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4163687","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4163687","identity":"rs-4163687","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}