Contrast-associated acute kidney injury in second-generation cryoballoon-based pulmonary vein isolation

Contrast-associated acute kidney injury in second-generation cryoballoon-based pulmonary vein isolation | 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 Article Contrast-associated acute kidney injury in second-generation cryoballoon-based pulmonary vein isolation Phillip Harms, Laura Rottner, Christian Heeger, Bruno Reissmann, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4592833/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 - An effective treatment of symptomatic Atrial fibrillation (AF) is the second-generation cryoballoon (CB2) based pulmonary vein isolation (PVI). However, this technique is associated with an increased exposure to contrast media and little is known about postprocedural acute kidney injury (AKI). Objective - We evaluated the incidence, characteristics and risk factors of contrast-associated AKI after CB2-based catheter ablation in a large patient cohort. Methods - 444 patients with symptomatic drug-refractory paroxysmal AF (PAF, n=236 [53%]) or persistent AF (n=208) who underwent CB2-based PVI were included. The study group was divided into four groups based on the estimated glomerular filtration rate (eGFR) documented the day before the procedure. Serum creatinine levels were measured before and 48 hours after the procedure. AKI was assessed using the KDIGO guidelines. Results - The overall incidence of AKI was 2.9% (13/444). Among the AKI group, the majority were in CKD stage 4 (2/7, 28.6%), followed by CKD stage 3 (7/111; 6.3%), CKD stage 1(1/70; 1.4%) and CKD stage 2 (3/256; 1.2%). Baseline CKD stage (HR 1.3659, 95% CI 0.05107 - 36.53, p = 0.033) was identified as independent predictor of AKI. Arterial hypertension was prevalent in the AKI group. Conclusions - The overall incidence of postcontrast AKI in CB2-based ablation of AF was low. Cryoablation PVI is a safe therapeutic option for individuals with CKD stages 1 and 2. However, in patients with CKD stages 3 and 4, it is associated with an increased incidence of AKI. Health sciences/Nephrology/Kidney diseases Health sciences/Cardiology Atrial fibrillation cryoballoon catheter ablation estimated glomerular filtration rate pulmonary vein isolation contrast-induced nephropathy Figures Figure 1 Figure 2 Figure 3 Introduction Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting 2 to 3% of the general population in Germany 1 . Untreated AF can cause severe complications such as heart failure, heart attack, stroke, and major bleeding 2 . Catheter ablation has emerged as the cornerstone treatment of AF and is an established method 3 . Radiofrequency (RF) is the most common energy source and cryoenergy delivered by a balloon the second most used method for catheter-guided pulmonary vein isolation (PVI) 4 . Cryoballoon PVI has been shown to be non-inferior to RF ablation in terms of safety and efficacy outcomes in patients with drug-refractory paroxysmal AF (PAF) 5 . However, patients who undergo cryoballoon PVI are exposed to a higher use of intravenous contrast media compared to radiofrequency ablation 6 . Although it is widely accepted that intravenous administration of iodinated contrast media is associated with acute kidney injury (AKI), less is known about the frequency and risk of post-interventional AKI in patients undergoing cryoballoon PVI. In this study, our objective was to evaluate changes in kidney function after cryoballoon PVI in a larger population of patients with symptomatic AF. Methods Study population In this retrospective study, we included 444 patients with symptomatic, drug-refractory paroxysmal or persistent AF who underwent pulmonary vein isolation using a second-generation cryoballoon (CB2) catheter between July 2012 and November 2019 at Asklepios Klinik St. Georg in Hamburg, Germany. The indications for catheter ablation for AF were in line with the latest guidelines. All patients gave written informed consent, and all patient information was anonymized. The study was approved by the local ethics committee and followed the Declaration of Helsinki (WF-027/ 15; Ethik-Kommission der Ärztekammer Hamburg). Preprocedural management Patients who were scheduled for catheter ablation treatment were admitted one day before to the procedure. At admission, transesophageal echocardiography was performed in all patients to exclude intracardiac thrombi and to determine the left atrial (LA) diameter and left ventricular ejection fraction (LVEF). Serum creatinine (SCr) and glomerular filtration rate (eGFR) measurement was obtained on the day before the procedure. In patients under treatment with novel oral anticoagulants (NOACs), anticoagulation was interrupted 24 h before the procedure. In patients on vitamin K antagonist therapy, anticoagulation was continued if the international normalized ratio (INR) was 2.0–3.0 on the day of the procedure. Ablation procedure The procedure was performed under deep conscious sedation using intravenous propofol, fentanyl and midazolam. Furthermore, patients were anticoagulated with intravenous heparin throughout the entire ablation procedure to prevent thrombus formation on the catheters, sheaths, left atrium and left atrial appendage and at ablation sites. An activated clotting time of > 300 s was targeted. For placement of a coronary sinus catheter, vascular access was obtained via the right femoral or left subclavian veins. To minimize the risk of thermal injury to the esophagus and fistula formation, a temperature probe (Sensitherm, St Jude Medical or Circa; Circa Scientific, Englewood, CO) was placed within the esophagus to measure intraluminal temperature during freeze cycles. The procedure was interrupted in case an intraluminal esophageal temperature of 10°C was reached. Left atrial access was gained by transseptal puncture under fluoroscopic guidance using a modified Brockenbrough technique and an 8.5 F transseptal sheath (SL 1, St. Jude Medical, Inc., St Paul, MN). In addition, pulmonary vein angiographies were performed to identify the individual PV ostia. Following PV venography, a second generation 28mm cryoballoon system (Arctic Front Advance, Medtronic, Inc.) was advanced to the ostium of the targeted PV, guided by a 20 mm inner circular mapping catheter (Achieve, Medtronic, Inc.) using a deflectable 12-Fr sheath (FlexCath Advance, Medtronic, Inc.). Subsequent inflation of the cryoballoon and placement on the pulmonary vein ostium led to the occlusion of the pulmonary vein. After the confirmation of complete PV ostium occlusion by contrast medium, the "time-to-isolation" guided ablation strategy was applied to achieve pulmonary vein isolation. This approach is characterized by continuous real-time recordings from the circular mapping catheter and is based on extension of the freeze time for an additional 120 seconds after documentation of PVI. In case no PV signal recording could be obtained, a standard freeze cycle of 180 s was performed. To avoid phrenic nerve damage during the freeze ablation of right pulmonary veins, phrenic nerve function was monitored by phrenic nerve stimulation with assessment of the diaphragmatic compound motor action potential (CMAP). This was achieved by the placement of a diagnostic catheter (7F, Webster, Biosense Webster, Diamond Bar, CA) inside the vena cava superior pacing at maximal output and a cycle length of 1000 ms. If decrease of diaphragmatic movement or CMAP amplitude reduction ≥ 30% was observed, energy delivery was stopped. The procedural endpoint was defined as persistent electrical PVI verified by spiral mapping catheter recordings 30 min after the last CB application. After the procedure, intravenous saline infusion with more than 1000 mL continued until the day after ablation. Postprocedural care After ablation, all patients underwent transthoracic echocardiography to rule out pericardial effusion. All patients were treated with proton pump inhibitors for 6 weeks. Low molecular weight heparin was administered in patients on a vitamin K antagonist with an INR < 2.0, until a therapeutic INR between 2 and 3 was achieved. NOACs were stopped the day before the procedure and re-started 6 hours after the procedure. Anticoagulation was continued for at least 3 months based on the individual’s CHA 2 DS 2 -VASc score. Antiarrhythmic drugs were continued for 3 months. Twelve-lead ECG and Holter recordings were performed before hospital discharge to confirm stable sinus rhythm. Evaluation of kidney function Classification of chronic kidney disease (CKD) was defined based on the eGFR calculation at baseline according to the KDIGO and KDOQI guidelines. We divided the study group into four groups according to eGFR. CKD stage 1 was defined as normal with eGFR ≥ 90 mL/min/1.73m², CKD stage 2 as mild with eGFR 60–89 mL/min/1.73m², CKD stage 3 as moderate with eGFR 30–59 mL/min/1.73m², and CKD stage 4 as severe with eGFR 15–29 mL/min/1.73m². Serum creatinine levels were measured before and 48 hours after the procedure. AKI was assessed using the KDIGO guidelines and was defined as a > 0.3 mg/dl increase in serum creatinine within 48 hours. The primary endpoint of this study was the incidence and characteristics of AKI after cryoballoon catheter ablation. Other analyses A complication was considered periprocedural if it occurred during the CB2 ablation procedure, within hospital stay, or within a 30-day period post-ablation. We defined a major complication according to the 2012 consensus statement for catheter ablation of atrial fibrillation; this included any complication that resulted in permanent injury or death, required intervention for management, or caused an extension of hospitalization beyond 48 hours ( 28 ). To assess the learning curve with the second-generation cryoballoon technique focusing on procedure duration, fluoroscopy time, contrast volume and complications, we divided the study population into two groups (first 222 patients and last 222 patients). Statistical Analysis Continuous variables are shown as mean and standard deviations or median with 25th and 75th percentiles. Categorical variables are presented as absolute numbers and percentages. Differences between baseline continuous variables were analyzed using Student’s t-test for parametric data. Differences between continuous procedural parameters (fluoroscopy duration and dose, procedure time, amount of contrast medium) were analyzed using Mann-Whitney’s U test or Kruskal-Wallis test for nonparametric data. Categorical variables were compared using the chi-square test or Fisher’s exact test. Exact confidence intervals were calculated based on the binomial distribution. Binary logistic regression analysis was performed to assess the predictors of AKI. A variable tree was used to illustrate the prevalence of hypertension in patients with acute kidney injury. Statistical analysis was performed using GraphPad Prism 9.0, IBM SPSS Statistics 29.0.0.0, and Jamovi 2.3.21. Statistical tests were two-sided and p < 0.05 was considered statistically significant. Results Patient characteristics We included 444 patients (mean age 66 ± 11 years, mean LA diameter 44 ± 9 mm; 202 [45%] women) who underwent CB2-PVI between July 2012 and November 2019 for symptomatic AF. 236/444 (53%) of the patients were diagnosed with PAF and 208/444 (47%) with persistent AF. The study group consisted of 70, 256, 111 and 7 patients in the CKD stages 1, 2, 3 and 4, respectively. Comparisons of the patients’ baseline demographics, clinical characteristics, and echocardiographic variables among the CKD groups are shown in Table 1 . Significant differences were found in age, gender, and comorbidities. Older individuals were more likely to have impaired kidney function. While the mean age was 56 ± 10 years in CKD stage 1, it was 79 ± 5 in the CKD stage 4 group. Furthermore, the prevalence of individual comorbidities such as arterial hypertension, diabetes mellitus, heart failure and coronary artery disease increased with the CKD stage. Accordingly, increased CHA2DS2-VASc and HAS-BLED scores were associated with higher levels of CKD markers. Table 1 Comparison of baseline characteristics among CKD groups Parameter CKD stage 1 (n = 70) CKD stage 2 (n = 256) CKD stage 3 (n = 111) CKD stage 4 (n = 7) p-value Age [years.] 56 ± 10 66 ± 10 72 ± 8 77 ± 5 < 0.001 Male sex 51 (73%) 135 (53%) 53 (48%) 4 (57%) 0.006 BMI [kg/m²] 28 ± 5 28 ± 6 28 ± 5 32 ± 6 0.306 Paroxysmal AF [%] 42 (60%) 141 (55%) 51 (46%) 2 (29%) 0.124 Persistent AF [%] 28 115 60 5 LA diameter [mm] 43 ± 6 44 ± 6 44 ± 6 47 ± 6 0.128 LVEF [%] 59 ± 9 59 ± 8 58 ± 11 49 ± 20 0.633 Art. Hypertension 33 (47%) 166 (65%) 87 (78%) 6 (86%) < 0.001 Diabetes mellitus 1 (1%) 34 (13%) 20 (18%) 0 (0%) 0.002 Heart failure 9 (13%) 18 (7%) 14 (13%) 3 (43%) 0.009 Coronary artery disease 1 (1%) 15 (6%) 14 (13%) 3 (43%) < 0.001 Stroke, TIA 0 (0%) 10 (4%) 1 (1%) 0 (0%) 0.054 CHA 2 DS 2 -VASc score 1.2 ± 1 2.32 ± 1 3.20 ± 1 4.14 ± 1 < 0.001 HASBLED score 1.11 ± 1 1.73 ± 1 2.15 ± 1 2.86 ± 1 < 0.001 The data are presented as number (%) or mean ± standard deviation. CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; LVEF, left ventricular ejection fraction; LA, left atrium; AF, atrial fibrillation. BMI, body-mass-index; TIA, transient ischemic attack Procedural data and complications PVI was performed in all 444 patients; 163 (36.6%) presented in AF at the day of the procedure. In 441 patients all veins could be successfully isolated. Mean procedure time, measured from time of femoral puncture until removal of the sheath, was 94.6 ± 35 minutes. The mean fluoroscopy time was 19.4 ± 8 minutes, the mean fluoroscopy dose was 2,772 ± 3,382 cGycm². A mean volume of 126 ± 41 ml of contrast agent was used. To study the learning curve and the eventual associated reduction in procedure duration, in fluoroscopy times or in contrast medium, we compared the first and second study population analyzed procedure duration, fluoroscopy times and contrast volume. The mean procedure duration shortened from 104.3 ± 37.01 to 84.9 ± 30.8 min (p < 0.001), and fluoroscopy time decreased from 20.5 ± 9.1 to 18.3 ± 7.0 min (p = 0.035) in the first and second group of patients. No significant differences regarding contrast media volume observed (128.5ml vs 123.1ml, p = 0.673) (Fig. 1 ). Periprocedural complication occurred in 45 cases (10%). Major complications were documented in 34 cases (7.9%), including 7 (1.6%) phrenic nerve paralysis (PNP), 18 (4.1%) with vascular access complications (groin hematomas, false aneurysms, AV fistula), 1 (0.2%) with severe hemoptysis, 1 (0.2%) with severe symptomatic gastroparesis and 4 (0.9%) with pericardial effusion with hemodynamic instability. In 3 cases (0.6%), the ablation was terminated prematurely due to PNP, peri-interventional CPR after hypoxia under anesthetic, and peri-interventional hematemesis. One patient died 4 weeks following ablation due to respiratory failure after nosocomial pneumonia (0.2%). Minor complications occurred in 11 cases (6.5%) including 4 (0.9%) with symptomatic oesophageal ulceration and 7 (1,6%) with pericardial effusion without hemodynamic compromise. Interestingly, the rate of complications tended to increase in the second half of the study population (8% vs 14%, p = 0.068) (Fig. 1 ). The documented complications are summarized in Table 2 . Table 2 Documented complications the AKI and non-AKI group Non-AKI (n = 431) AKI (n = 13) Total Major complications n (%) 39 6 45 (10%) Phrenic nerve paralysis (PNP) 6 1 7 (1.6%) Major groin complication (groin haematomas, false aneurysms, AV fistula) 18 0 18 (4.1%) Pericardial effusion (haemodynamically relevant requiring pericardiocentesis) 2 2 4 (0.9%) Gastroparesis 1 0 1 (0.2%) CPR because of hypoxia under anaesthetic 1 0 1 (0.2%) Haematemesis 1 0 1 (0.2%) Procedure related haemoptysis 1 0 1 (0.2%) Procedure related death (respiratory insufficiency) 0 1 1 (0.2%) Minor complications Pericardial effusion (haemodynamically not relevant) 6 1 7 (1.6%) Oesophageal ulceration 3 1 Values are n (%) AV, arteriovenous Incidence of AKI SCr level after catheter ablation was measured in all 444 patients. The overall incidence of AKI recorded after CB2-based PVI was very low (2.9%). As shown in Fig. 2 , most patients who developed AKI were in the CKD stage 4 group (2/7, 28.6%), followed by CKD stage 3 (7/111; 6.3%), CKD stage 1( 1/70; 1.4%) and CKD stage 2 (3/256; 1.2%). Figure 3 shows an alluvial diagram illustrating the alteration of kidney function according to eGFR from baseline to 48 hours of follow-up. The height of each stream represents the proportion of patients. Some patients eventually progressed to a higher CKD stage without meeting the criteria for AKI. Table 3 shows the comparison of baseline demographic and procedural characteristics between the AKI and non-AKI groups. The groups were unevenly distributed due to the low incidence of postcontrast AKI. However, significant differences were found in the incidence of arterial hypertension (AKI 92%, non-AKI 65%, p = 0.041), HASBLED score (AKI 2.38 ± 1, non-AKI 1.74 ± 1, p = 0.041), rhythm at the beginning of the procedure (AKI 69%, non-AKI 36%, p = 0.019), baseline creatinine (AKI 1.46 ± 0.62, non-AKI 1.01 ± 0.28, p = 0.002), complication rate (AKI 42%, non-AKI 9%, p = 0.001) and BW- and baseline SCr-adjusted maximum CM dose (CM × SCr/BW) (AKI 2.2 ± 1.4, non-AKI 1.5 ± 0.6; p = 0.027). The notion that the relationship between AKI and the adjusted CM dose may also be threshold-dependent was explored by using a cut-off of 2.7 proposed by Yamamoto et al 29 . Patients exceeding the threshold of 2.7 were more common in the AKI-group than in the non-AKI cohort (23% vs 4%; p = 0.017). A multivariate analysis was performed to determine predicting baseline characteristics for AKI after catheter ablation. As shown in Table 4 , baseline CKD stage (HR 1.3659, 95% CI 0.05107–36.53, p = 0.033) was identified as an independent predictor of AKI. However, individuals with type 2 diabetes were highly underrepresented in our study group. Hence, conclusions on the effects of type 2 diabetes on postcontrast AKI is limited. Table 3 Comparison of baseline demographic and procedural characteristics between the AKI and non-AKI group Parameter Non-AKI (n = 431) AKI (n = 13) p-value Age [years.] 66 ± 10.5 70 ± 10.8 0.082 Male sex 234 (54%) 9 (69%) 0.399 BMI [kg/m²] 28 ± 5 28 ± 6 0.822 AF type (persistent AF), [%] 201 (47%) 7 (54%) 0.779 Echocardiographic data LA diameter [mm] 44 ± 6 41 ± 5 0.333 LVEF [%] 59 ± 9 57 ± 14 0.696 Comorbidities Art. Hypertension 280 (65%) 12 (92%) 0.041 Diabetes mellitus 54 (13%) 8 (13%) 1.000 Heart failure 42 (10%) 2 (15%) 0.375 Coronary artery disease 30 (1%) 3 (6%) 0.064 Stroke, TIA 36 (8%) 2 (15%) 0.307 CHA2DS2-VASc score 2.4 ± 1.5 3.15 ± 1.5 0.483 HASBLED score 1.74 ± 1 2.38 ± 1 0.041 Renal function Baseline creatinine 1.01 ± 0.28 1.46 ± 0.62 0.002 Ablation procedure Rhythm at start [AF] 154 (36%) 9 (69%) 0.019 Procedure duration [mins] 94.56 ± 35.1 97.08 ± 46.36 0.968 Fluoroscopy duration [mins] 19.27 ± 8.1 23.54 ± 10.07 0.098 Fluoroscopy dosage [cGy*cm²] 2760 ± 3404 3193 ± 2605 0.241 Contrast medium [ml] 126 ± 41 132 ± 54 0.472 Bodyweight-adapted CM volume [ml/kg] 1.51 ± 0.56 1.65 ± 0.92 0.664 CM × SCr/BW ratio 1,5 ± 0.6 2.2 ± 1.4 0.027 CM × SCr/BW ratio > 2.7, n (%) 17 ( 4 ) 3 ( 23 ) 0.017 Complications 39 (9%) 6 (42%) 0.001 The data are presented as number (%) or mean ± standard deviation. CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; LVEF, left ventricular ejection fraction; LA, left atrium; AF, atrial fibrillation. BMI, body-mass-index; TIA, transient ischemic attack Table 4 Logistic regression model for analysis of AKI predictors Variable Odds ratio (95% CI) p-value Age 1.0220 (0.92766–1.13) 0.664 Male 4.4666 (0.83970–23.76) 0.726 Persistent AF (vs paroxysmal) 1.0235 (0.27907–3.75) 0.803 BMI 0.9519 (0.76400–1.19) 0.666 History of heart failure 0.7884 (0.10741–5.79) 0.817 Diabetes mellitus 6.0568 (0.44745–81.99) 0.121 Arterial hypertension 0.2245 (0.02072–2.43) 0.170 HASBLED score 0.7309 (0.25794–2.07) 0.555 CHA2DS2-Vasc score 0.9334 (0.40493–2.15) 0.872 Baseline CKD stage 1.3659 (0.05107–36.53) 0.033 Volume of contrast medium 1.0231 (0.97863–1.07) 0.309 Bodyweight-adapted CM volume 0.1469 (0.00696–3.10) 0.231 Fluoroscopy duration 0.9341 (0.86638–1.01) 0.087 CI, confidence interval; AF, atrial fibrillation; LVEF, left ventricular ejection fraction; and eGFR, estimated glomerular filtration rate. BMI, body-mass-index Discussion The present large retrospective study reporting on the incidence of postprocedural AKI in second-generation cryoballoon-based PVI has two main findings. First, the overall incidence of AKI was very low (2.9%) and demonstrates the overestimation of the risk of contrast-associated AKI. Second, patients with CKD stage 4 and arterial hypertension have the highest risk of developing AKI. Contrast-associated AKI is a serious complication resulting from the administration of contrast media during cryoballoon-based PVI and is therefore considered a limitation for this otherwise successful treatment option 11 . In the past, many studies have been conducted on the incidence of AKI in patients undergoing interventional procedures, with rates reported between 0% and 21% depending on different factors such as comorbidities, type of procedure, definition of AKI, and time of post-contrast serum creatinine measurement 12,13,14;15 . It is well known that preexisting impaired renal function is a risk factor and progressive decline in renal function can be precipitated by contrast media administration 13,16 . However, little is known about its significance in clinical practice due to the lack of specific data from a large patient cohort who underwent CB ablation. In the present study, the overall incidence of AKI was very low and has been exaggerated in clinical practice. In view of these data there appears to be no evidence to categorically withhold contrast media based on kidney function. If contrast media administration is clinically indicated, consideration should be given to potential risks and benefits as well as alternative imaging strategies 17, 22 . An association between contrast volume and AKI has been previously addressed in several reports. In a study by Brown and his colleagues with 10,065 patients undergoing PCI, they reported an increased risk of AKI in patients exposed to higher doses of contrast media than in those who received lower doses 21 . The present study also demonstrates an association between AKI and CM dose calculated by CM × SCr/BW. The notion that the relationship between these two variables may also be threshold-dependent was confirmed by using a cut-off of 2.7 proposed by Yamamoto et al 29 . A learning curve with the second-generation cryoballoon technique was observed regarding procedure time and fluoroscopy time, but not in use of contrast media volume and complication rate. Our data also show an association between AKI and periinterventional complications, already described in previous studies 29,30 . Szegedi et al. found an association between pre-existing conditions such as hypertension and higher CHA2DS2-VASc score with a higher risk for procedure-related adverse events 31 . In the present study, the prevalence of arterial hypertension, the CHADS VASC score and the HAS BLED score were higher in the AKI group than in the non-AKI group. Existing literature has reported an increased risk of AKI in patients with comorbidities 13,16,18,19 . It is well known that high systolic blood pressure is a risk factor for AKI due to the impairment the normal functioning of renal blood vessels 23 . As a result, especially patients with preexisting impaired renal function become more vulnerable to the effects of contrast media 24 Postprocedural AKI also has significant prognostic implications for patients after cryoballoon ablation. An association between impaired renal function and the recurrence of AF has been reported by Yanagisawa et al. The study with 110 patients who underwent second-generation cryoballoon catheter ablation demonstrated that patients with CKD stage 3 (eGFR 30–59.9 mL/min/1.73 m²) had significantly worse prognosis than patients in other CKD stages. Moreover, CKD stage 3 was associated with a higher recurrence rate and was identified as an independent predictor of recurrence. AF recurrence after PVI requires multiple procedures to maintain sinus rhythm and leads to a relevant impairment of long-term success 27 . In the present study, baseline CKD stage was identified as an independent predictor of AKI. Of note, it is also relevant to know which CKD stage is at increased risk of deterioration in renal function. We found that the prevalence of AKI was high in CKD stage 4. . According to the guidelines of the American College of Radiology and the National Kidney Foundation regarding the administration of an iodine-based contrast agent, patients with an eGFR less than 30 mL/min/1.73m² prior to contrast agent administration are at a potential risk of AKI 17 . Hence, preventive measures such as hydration and contrast media dose reduction are necessary for patients at risk following guidelines’ recommendation 25, 26 . Alternative techniques available for verifying pulmonary vein occlusion without the use of contrast media include occlusion tool software, saline injection-based occlusion tools, or direct pressure monitoring and should be strongly considered 32, 33, 34 . Limitations The current study is a retrospective, monocentric analysis with limitations ascribed to such type of design. Neither the pre- and post-procedural fluid intake nor the administration of nephrotoxic medication were consistently documented. Such documentation would have been desirable, as adequate hydration can reduce the risk of post-contrast ANV and some medications can promote the deterioration in renal function. Also, due to the low incidence of post-contrast AKI, the statistical analysis of independent predictors was limited and a conclusion about the impact on contrast AKI is difficult. Conclusions Our study demonstrates that cryoballoon ablations are associated with a low incidence of acute renal injury, indicating their relative safety in terms of immediate renal impacts. Patients with CKD stages 1 and 2 were less affected by acute kidney injury following cryoablation. These findings demonstrate that cryoablation PVI is a safe therapeutic option for individuals with CKD stages 1 and 2 without significant risk of AKI. However, a contrasting trend is observed in patients with CKD stages 3 and 4. In this subset of patients, cryoablations are linked with an increased incidence of adverse renal events. The increased risk should be considered in when planning an ablation. Our findings advocate a more cautious approach in this vulnerable patients and for the consideration of using alternative ablation techniques without the use of contrast media in this patient demographic to mitigate the risk of further deterioration in renal function. Declarations Author contributions CL conceived and designed the study. She also provided critical revisions and approved the final version of the manuscript. PH was responsible for data collection and management. He conducted the primary statistical analyses and wrote the initial draft of the manuscript. LR, SM , FO and TM contributed to the data analysis and interpretation. PW and MS supported the statistical analysis of the data AM, KHK, CHH and BR supervised the project, contributed to the study design, and provided important intellectual content. All authors have approved the submitted version. Availability of Data and Materials The datasets used and analyzed during the current study are available from the corresponding author on reasonable request. Additional Information Competing Interests Statement The authors declare no competing interests. References Schnabel RB, Wilde S, Wild PS, Münzel T, Blankenberg S. 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Use of Intravenous Iodinated Contrast Media in Patients with Kidney Disease: Consensus Statements from the American College of Radiology and the National Kidney Foundation. Radiology. 2020; 294:660-668. Benjamin EJ, Levy D, Vaziri SM, D’Agostino RB, Belanger AJ, Wolf PA. Independent risk factors for atrial fibrillation in a population-based cohort. The Framingham Heart Study. JAMA. 1994;271:840-4. Movahed MR, Hashemzadeh M, Jamal MM. Diabetes mellitus is a strong, independent risk for atrial fibrillation and flutter in addition to other cardiovascular disease. Int J Cardiol. 2005;105:315-8. Conen D, Buerkle G, Perruchoud AP, Buettner HJ, Mueller C. Hypertension is an independent risk factor for contrast nephropathy after percutaneous coronary intervention. Int J Cardiol. 2006;110:237-41. Brown JR, Robb JF, Block CA, Schoolwerth AC, Kaplan AV, O’Connor GT, Solomon RJ, Malenka DJ. Does safe dosing of iodinated contrast prevent contrast-induced AKI? Circ Cardiovasc Interv. 2010;3:346–50. Katzberg RW, Newhouse JH. Intravenous contrast medium-induced nephrotoxicity: is the medical risk as great as we have come to believe? Radiology 2010;256:21–28. Dylewska M, Chomicka I, Małyszko J. Hypertension in patients with acute kidney injury. Wiad Lek. 2019;72(11 cz 2):2199-2201. Lun Z, Mai Z, Liu L, Chen G, Li H, Ying M, Wang B, Chen S, Yang Y, Liu J, Chen J, Ye J, Liu Y. Hypertension as a Risk Factor for Contrast-Associated Acute Kidney Injury: A Meta-Analysis Including 2,830,338 Patients. Kidney Blood Press Res. 2021;46:670-692. Stacul F, van der Molen AJ, Reimer P, Webb JA, Thomsen HS, Morcos SK, Almen T, Aspelin P, Bellin MF, Clement O, Heinz-Peer G. Contrast induced nephropathy: updated ESUR Contrast Media Safety Committee guidelines. Eur Radiol 2011;12:2527–2541. Seeliger E, Becker K, Ladwig M, Wronski T, Persson PB, Flemming B. Up to 50-fold increase in urine viscosity with iso-osmolar contrast media in the rat. Radiology 2010;256:406–414. Yanagisawa S, Inden Y, Kato H, Fujii A, Mizutani Y, Ito T, Kamikubo Y, Kanzaki Y, Ando M, Hirai M, Shibata R, Murohara T. Impaired renal function is associated with recurrence after cryoballoon catheter ablation for paroxysmal atrial fibrillation: A potential effect of non-pulmonary vein foci. J Cardiol. 2017;69:3-10. Calkins H, Kuck KH, Cappato R, Brugada J, Camm AJ, Chen SA, Crijns HJ, Damiano RJ, Jr., Davies DW, DiMarco J, Edgerton J, Ellenbogen K, Ezekowitz MD, Haines DE, Haissaguerre M, Hindricks G, Iesaka Y, Jackman W, Jalife J, Jais P, Kalman J, Keane D, Kim YH, Kirchhof P, Klein G, Kottkamp H, Kumagai K, Lindsay BD, Mansour M, Marchlinski FE, McCarthy PM, Mont JL, Morady F, Nademanee K, Nakagawa H, Natale A, Nattel S, Packer DL, Pappone C, Prystowsky E, Raviele A, Reddy V, Ruskin JN, Shemin RJ, Tsao HM, Wilber D. 2012 HRS/EHRA/ECAS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design. Europace 2012;14:528-606. Yamamoto M, Hayashida K, Mouillet G, Chevalier B, Meguro K, Watanabe Y, Dubois-Rande JL, Morice MC, Lefèvre T, Teiger E. Renal function-based contrast dosing predicts acute kidney injury following transcatheter aortic valve implantation. JACC Cardiovasc Interv. 2013 May;6(5):479-86. James MT, Ghali WA, Knudtson ML, Ravani P, Tonelli M, Faris P, Pannu N, Manns BJ, Klarenbach SW, Hemmelgarn BR; Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) Investigators. Associations between acute kidney injury and cardiovascular and renal outcomes after coronary angiography. Circulation. 2011 Feb 1;123(4):409-16. Szegedi N, Széplaki G, Herczeg S, Tahin T, Salló Z, Nagy VK, Osztheimer I, Özcan EE, Merkely B, Gellér L. Repeat procedure is a new independent predictor of complications of atrial fibrillation ablation. Europace. 2019 May 1;21(5):732-737. Cauti FM, Rossi P, Polselli M, Iaia L, Giannitti CM, Bianchi S. Occlusion tool software for pulmonary vein occlusion verification in atrial fibrillation cryoballoon ablation to avoid the use of contrast injection. HeartRhythm Case Rep. 2020 May 23;6(8):516-519. Rottner L, Obergassel J, Borof K, My I, Moser F, Lemoine M, Wenzel JP, Kirchhof P, Ouyang F, Reissmann B, Metzner A, Rillig A. A novel saline-based occlusion tool allows for dye-less cryoballoon-based pulmonary vein isolation and fluoroscopy reduction. Front Cardiovasc Med. 2023 Mar 24;10:1156500. Sunaga A, Masuda M, Asai M, Iida O, Okamoto S, Ishihara T, Nanto K, Kanda T, Tsujimura T, Matsuda Y, Okuno S, Mano T. Pressure monitoring predicts pulmonary vein occlusion in cryoballoon ablation. J Interv Card Electrophysiol. 2018 Oct;53(1):115-121. 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. 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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-4592833","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":325606745,"identity":"9a3a6190-833b-4e85-a28c-ba5d116c3849","order_by":0,"name":"Phillip Harms","email":"","orcid":"","institution":"Asklepios Klinik St. Georg","correspondingAuthor":false,"prefix":"","firstName":"Phillip","middleName":"","lastName":"Harms","suffix":""},{"id":325606746,"identity":"d706289f-ddce-45bf-bf55-cba2c73de0c6","order_by":1,"name":"Laura Rottner","email":"","orcid":"","institution":"Asklepios Klinik St. Georg","correspondingAuthor":false,"prefix":"","firstName":"Laura","middleName":"","lastName":"Rottner","suffix":""},{"id":325606747,"identity":"39f039c0-dc9d-45ef-9fa3-89223c4cec22","order_by":2,"name":"Christian Heeger","email":"","orcid":"","institution":"Asklepios Klinik St. Georg","correspondingAuthor":false,"prefix":"","firstName":"Christian","middleName":"","lastName":"Heeger","suffix":""},{"id":325606748,"identity":"64b7dec1-1f2b-44d8-96d6-4c1f582daf7a","order_by":3,"name":"Bruno Reissmann","email":"","orcid":"","institution":"Asklepios Klinik St. Georg","correspondingAuthor":false,"prefix":"","firstName":"Bruno","middleName":"","lastName":"Reissmann","suffix":""},{"id":325606749,"identity":"b6521bd3-07c3-4f33-b040-9491dccf1ff2","order_by":4,"name":"Feifan Ouyang","email":"","orcid":"","institution":"Asklepios Klinik St. 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Georg","correspondingAuthor":false,"prefix":"","firstName":"Tilman","middleName":"","lastName":"Maurer","suffix":""},{"id":325606756,"identity":"fdbfdc87-f13c-4a8d-95ee-ca72be66ca5b","order_by":11,"name":"Christine Lemes","email":"data:image/png;base64,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","orcid":"","institution":"Asklepios Klinik St. Georg","correspondingAuthor":true,"prefix":"","firstName":"Christine","middleName":"","lastName":"Lemes","suffix":""}],"badges":[],"createdAt":"2024-06-17 08:36:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4592833/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4592833/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":60624961,"identity":"8673d63a-ca06-42fc-ac8a-4c372d2d8687","added_by":"auto","created_at":"2024-07-18 22:19:10","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":652320,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eLearning curves in the second-generation cryoballoon\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eProcedure duration and fluoroscopy times and contrast volume – comparison between first and second study population.\u003c/p\u003e","description":"","filename":"Onlinefloatimage1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4592833/v1/d0a3ddc2059cce8cf81cdaf8.jpg"},{"id":60624962,"identity":"31c50ea6-38a6-42c6-a00b-fa0072e305ed","added_by":"auto","created_at":"2024-07-18 22:19:10","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":169148,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eIncidence of AKI after CB2-based catheter ablation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAKI, acute kidney injury; CKD, chronic kidney disease. AKF-group n =13.\u003c/p\u003e","description":"","filename":"Onlinefloatimage2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4592833/v1/c8cc905f4abd87957f8c00d7.jpg"},{"id":60624959,"identity":"03f39aa3-6fd6-4ac7-98af-20066047ba41","added_by":"auto","created_at":"2024-07-18 22:19:10","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":689450,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eOnset of AKI among the CKD groups 48 hours after cryoballoon\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe bars in this alluvial diagram represent the eGFR KDIGO stage at baseline (on the left of the diagram) and after 48 hours of follow-up (on the middle of diagram). The right bar illustrates the onset of AKI. The height of the bars represents the proportion of patients.\u003c/p\u003e","description":"","filename":"Onlinefloatimage3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4592833/v1/e0dec85d00a8d6fb8f08b7fc.jpg"},{"id":71953411,"identity":"75d1b280-c8c0-4629-a5b6-a8d4894bb51b","added_by":"auto","created_at":"2024-12-20 05:02:06","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2232977,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4592833/v1/e5612955-a215-4317-bd02-607bc1fa7e7b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Contrast-associated acute kidney injury in second-generation cryoballoon-based pulmonary vein isolation","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAtrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting 2 to 3% of the general population in Germany\u003csup\u003e1\u003c/sup\u003e. Untreated AF can cause severe complications such as heart failure, heart attack, stroke, and major bleeding\u003csup\u003e2\u003c/sup\u003e. Catheter ablation has emerged as the cornerstone treatment of AF and is an established method\u003csup\u003e3\u003c/sup\u003e. Radiofrequency (RF) is the most common energy source and cryoenergy delivered by a balloon the second most used method for catheter-guided pulmonary vein isolation (PVI)\u003csup\u003e4\u003c/sup\u003e. Cryoballoon PVI has been shown to be non-inferior to RF ablation in terms of safety and efficacy outcomes in patients with drug-refractory paroxysmal AF (PAF)\u003csup\u003e5\u003c/sup\u003e. However, patients who undergo cryoballoon PVI are exposed to a higher use of intravenous contrast media compared to radiofrequency ablation\u003csup\u003e6\u003c/sup\u003e. Although it is widely accepted that intravenous administration of iodinated contrast media is associated with acute kidney injury (AKI), less is known about the frequency and risk of post-interventional AKI in patients undergoing cryoballoon PVI. In this study, our objective was to evaluate changes in kidney function after cryoballoon PVI in a larger population of patients with symptomatic AF.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy population\u003c/h2\u003e \u003cp\u003eIn this retrospective study, we included 444 patients with symptomatic, drug-refractory paroxysmal or persistent AF who underwent pulmonary vein isolation using a second-generation cryoballoon (CB2) catheter between July 2012 and November 2019 at Asklepios Klinik St. Georg in Hamburg, Germany. The indications for catheter ablation for AF were in line with the latest guidelines. All patients gave written informed consent, and all patient information was anonymized. The study was approved by the local ethics committee and followed the Declaration of Helsinki (WF-027/ 15; Ethik-Kommission der \u0026Auml;rztekammer Hamburg).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003ePreprocedural management\u003c/h2\u003e \u003cp\u003ePatients who were scheduled for catheter ablation treatment were admitted one day before to the procedure. At admission, transesophageal echocardiography was performed in all patients to exclude intracardiac thrombi and to determine the left atrial (LA) diameter and left ventricular ejection fraction (LVEF). Serum creatinine (SCr) and glomerular filtration rate (eGFR) measurement was obtained on the day before the procedure. In patients under treatment with novel oral anticoagulants (NOACs), anticoagulation was interrupted 24 h before the procedure. In patients on vitamin K antagonist therapy, anticoagulation was continued if the international normalized ratio (INR) was 2.0\u0026ndash;3.0 on the day of the procedure.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eAblation procedure\u003c/h2\u003e \u003cp\u003eThe procedure was performed under deep conscious sedation using intravenous propofol, fentanyl and midazolam. Furthermore, patients were anticoagulated with intravenous heparin throughout the entire ablation procedure to prevent thrombus formation on the catheters, sheaths, left atrium and left atrial appendage and at ablation sites. An activated clotting time of \u0026gt;\u0026thinsp;300 s was targeted. For placement of a coronary sinus catheter, vascular access was obtained via the right femoral or left subclavian veins. To minimize the risk of thermal injury to the esophagus and fistula formation, a temperature probe (Sensitherm, St Jude Medical or Circa; Circa Scientific, Englewood, CO) was placed within the esophagus to measure intraluminal temperature during freeze cycles. The procedure was interrupted in case an intraluminal esophageal temperature of 10\u0026deg;C was reached. Left atrial access was gained by transseptal puncture under fluoroscopic guidance using a modified Brockenbrough technique and an 8.5 F transseptal sheath (SL 1, St. Jude Medical, Inc., St Paul, MN). In addition, pulmonary vein angiographies were performed to identify the individual PV ostia. Following PV venography, a second generation 28mm cryoballoon system (Arctic Front Advance, Medtronic, Inc.) was advanced to the ostium of the targeted PV, guided by a 20 mm inner circular mapping catheter (Achieve, Medtronic, Inc.) using a deflectable 12-Fr sheath (FlexCath Advance, Medtronic, Inc.). Subsequent inflation of the cryoballoon and placement on the pulmonary vein ostium led to the occlusion of the pulmonary vein. After the confirmation of complete PV ostium occlusion by contrast medium, the \"time-to-isolation\" guided ablation strategy was applied to achieve pulmonary vein isolation. This approach is characterized by continuous real-time recordings from the circular mapping catheter and is based on extension of the freeze time for an additional 120 seconds after documentation of PVI. In case no PV signal recording could be obtained, a standard freeze cycle of 180 s was performed. To avoid phrenic nerve damage during the freeze ablation of right pulmonary veins, phrenic nerve function was monitored by phrenic nerve stimulation with assessment of the diaphragmatic compound motor action potential (CMAP). This was achieved by the placement of a diagnostic catheter (7F, Webster, Biosense Webster, Diamond Bar, CA) inside the vena cava superior pacing at maximal output and a cycle length of 1000 ms. If decrease of diaphragmatic movement or CMAP amplitude reduction\u0026thinsp;\u0026ge;\u0026thinsp;30% was observed, energy delivery was stopped. The procedural endpoint was defined as persistent electrical PVI verified by spiral mapping catheter recordings 30 min after the last CB application. After the procedure, intravenous saline infusion with more than 1000 mL continued until the day after ablation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003ePostprocedural care\u003c/h2\u003e \u003cp\u003eAfter ablation, all patients underwent transthoracic echocardiography to rule out pericardial effusion. All patients were treated with proton pump inhibitors for 6 weeks. Low molecular weight heparin was administered in patients on a vitamin K antagonist with an INR\u0026thinsp;\u0026lt;\u0026thinsp;2.0, until a therapeutic INR between 2 and 3 was achieved. NOACs were stopped the day before the procedure and re-started 6 hours after the procedure. Anticoagulation was continued for at least 3 months based on the individual\u0026rsquo;s CHA\u003csub\u003e2\u003c/sub\u003eDS\u003csub\u003e2\u003c/sub\u003e-VASc score. Antiarrhythmic drugs were continued for 3 months. Twelve-lead ECG and Holter recordings were performed before hospital discharge to confirm stable sinus rhythm.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eEvaluation of kidney function\u003c/h2\u003e \u003cp\u003e Classification of chronic kidney disease (CKD) was defined based on the eGFR calculation at baseline according to the KDIGO and KDOQI guidelines. We divided the study group into four groups according to eGFR. CKD stage 1 was defined as normal with eGFR\u0026thinsp;\u0026ge;\u0026thinsp;90 mL/min/1.73m\u0026sup2;, CKD stage 2 as mild with eGFR 60\u0026ndash;89 mL/min/1.73m\u0026sup2;, CKD stage 3 as moderate with eGFR 30\u0026ndash;59 mL/min/1.73m\u0026sup2;, and CKD stage 4 as severe with eGFR 15\u0026ndash;29 mL/min/1.73m\u0026sup2;. Serum creatinine levels were measured before and 48 hours after the procedure. AKI was assessed using the KDIGO guidelines and was defined as a\u0026thinsp;\u0026gt;\u0026thinsp;0.3 mg/dl increase in serum creatinine within 48 hours. The primary endpoint of this study was the incidence and characteristics of AKI after cryoballoon catheter ablation.\u003c/p\u003e \u003cp\u003eOther analyses\u003c/p\u003e \u003cp\u003eA complication was considered periprocedural if it occurred during the CB2 ablation procedure, within hospital stay, or within a 30-day period post-ablation. We defined a major complication according to the 2012 consensus statement for catheter ablation of atrial fibrillation; this included any complication that resulted in permanent injury or death, required intervention for management, or caused an extension of hospitalization beyond 48 hours (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTo assess the learning curve with the second-generation cryoballoon technique focusing on procedure duration, fluoroscopy time, contrast volume and complications, we divided the study population into two groups (first 222 patients and last 222 patients).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eContinuous variables are shown as mean and standard deviations or median with 25th and 75th percentiles. Categorical variables are presented as absolute numbers and percentages. Differences between baseline continuous variables were analyzed using Student\u0026rsquo;s t-test for parametric data. Differences between continuous procedural parameters (fluoroscopy duration and dose, procedure time, amount of contrast medium) were analyzed using Mann-Whitney\u0026rsquo;s U test or Kruskal-Wallis test for nonparametric data. Categorical variables were compared using the chi-square test or Fisher\u0026rsquo;s exact test. Exact confidence intervals were calculated based on the binomial distribution. Binary logistic regression analysis was performed to assess the predictors of AKI. A variable tree was used to illustrate the prevalence of hypertension in patients with acute kidney injury. Statistical analysis was performed using GraphPad Prism 9.0, IBM SPSS Statistics 29.0.0.0, and Jamovi 2.3.21. Statistical tests were two-sided and p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003ePatient characteristics\u003c/h2\u003e \u003cp\u003eWe included 444 patients (mean age 66\u0026thinsp;\u0026plusmn;\u0026thinsp;11 years, mean LA diameter 44\u0026thinsp;\u0026plusmn;\u0026thinsp;9 mm; 202 [45%] women) who underwent CB2-PVI between July 2012 and November 2019 for symptomatic AF. 236/444 (53%) of the patients were diagnosed with PAF and 208/444 (47%) with persistent AF. The study group consisted of 70, 256, 111 and 7 patients in the CKD stages 1, 2, 3 and 4, respectively. Comparisons of the patients\u0026rsquo; baseline demographics, clinical characteristics, and echocardiographic variables among the CKD groups are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Significant differences were found in age, gender, and comorbidities. Older individuals were more likely to have impaired kidney function. While the mean age was 56\u0026thinsp;\u0026plusmn;\u0026thinsp;10 years in CKD stage 1, it was 79\u0026thinsp;\u0026plusmn;\u0026thinsp;5 in the CKD stage 4 group. Furthermore, the prevalence of individual comorbidities such as arterial hypertension, diabetes mellitus, heart failure and coronary artery disease increased with the CKD stage. Accordingly, increased CHA2DS2-VASc and HAS-BLED scores were associated with higher levels of CKD markers.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of baseline characteristics among CKD groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e Parameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCKD stage 1\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;70)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCKD stage 2\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;256)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCKD stage 3\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;111)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCKD stage 4\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;7)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge [years.]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e56\u0026thinsp;\u0026plusmn;\u0026thinsp;10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e66\u0026thinsp;\u0026plusmn;\u0026thinsp;10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e72\u0026thinsp;\u0026plusmn;\u0026thinsp;8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e77\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale sex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e51 (73%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e135 (53%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e53 (48%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4 (57%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.006\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI [kg/m\u0026sup2;]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e28\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e32\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.306\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParoxysmal AF [%]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42 (60%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e141 (55%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e51 (46%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2 (29%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.124\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePersistent AF [%]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e115\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLA diameter [mm]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e43\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e44\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e44\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e47\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.128\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLVEF [%]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59\u0026thinsp;\u0026plusmn;\u0026thinsp;9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59\u0026thinsp;\u0026plusmn;\u0026thinsp;8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e58\u0026thinsp;\u0026plusmn;\u0026thinsp;11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e49\u0026thinsp;\u0026plusmn;\u0026thinsp;20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.633\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eArt. Hypertension\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e33 (47%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e166 (65%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e87 (78%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6 (86%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiabetes mellitus\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34 (13%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20 (18%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeart failure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9 (13%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18 (7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14 (13%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3 (43%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.009\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCoronary artery disease\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15 (6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14 (13%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3 (43%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStroke, TIA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10 (4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.054\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCHA\u003csub\u003e2\u003c/sub\u003eDS\u003csub\u003e2\u003c/sub\u003e-VASc score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.32\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.20\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.14\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHASBLED score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.11\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.73\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.15\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.86\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eThe data are presented as number (%) or mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eCKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; LVEF, left ventricular ejection fraction; LA, left atrium; AF, atrial fibrillation. BMI, body-mass-index; TIA, transient ischemic attack\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eProcedural data and complications\u003c/h2\u003e \u003cp\u003ePVI was performed in all 444 patients; 163 (36.6%) presented in AF at the day of the procedure. In 441 patients all veins could be successfully isolated. Mean procedure time, measured from time of femoral puncture until removal of the sheath, was 94.6\u0026thinsp;\u0026plusmn;\u0026thinsp;35 minutes. The mean fluoroscopy time was 19.4\u0026thinsp;\u0026plusmn;\u0026thinsp;8 minutes, the mean fluoroscopy dose was 2,772\u0026thinsp;\u0026plusmn;\u0026thinsp;3,382 cGycm\u0026sup2;. A mean volume of 126\u0026thinsp;\u0026plusmn;\u0026thinsp;41 ml of contrast agent was used. To study the learning curve and the eventual associated reduction in procedure duration, in fluoroscopy times or in contrast medium, we compared the first and second study population analyzed procedure duration, fluoroscopy times and contrast volume. The mean procedure duration shortened from 104.3\u0026thinsp;\u0026plusmn;\u0026thinsp;37.01 to 84.9\u0026thinsp;\u0026plusmn;\u0026thinsp;30.8 min (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and fluoroscopy time decreased from 20.5\u0026thinsp;\u0026plusmn;\u0026thinsp;9.1 to 18.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.0 min (p\u0026thinsp;=\u0026thinsp;0.035) in the first and second group of patients. No significant differences regarding contrast media volume observed (128.5ml vs 123.1ml, p\u0026thinsp;=\u0026thinsp;0.673) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Periprocedural complication occurred in 45 cases (10%). Major complications were documented in 34 cases (7.9%), including 7 (1.6%) phrenic nerve paralysis (PNP), 18 (4.1%) with vascular access complications (groin hematomas, false aneurysms, AV fistula), 1 (0.2%) with severe hemoptysis, 1 (0.2%) with severe symptomatic gastroparesis and 4 (0.9%) with pericardial effusion with hemodynamic instability. In 3 cases (0.6%), the ablation was terminated prematurely due to PNP, peri-interventional CPR after hypoxia under anesthetic, and peri-interventional hematemesis. One patient died 4 weeks following ablation due to respiratory failure after nosocomial pneumonia (0.2%). Minor complications occurred in 11 cases (6.5%) including 4 (0.9%) with symptomatic oesophageal ulceration and 7 (1,6%) with pericardial effusion without hemodynamic compromise. Interestingly, the rate of complications tended to increase in the second half of the study population (8% vs 14%, p\u0026thinsp;=\u0026thinsp;0.068) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The documented complications are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDocumented complications the AKI and non-AKI group\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNon-AKI\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;431)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAKI\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;13)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMajor complications n (%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e45 (10%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePhrenic nerve paralysis (PNP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (1.6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMajor groin complication (groin haematomas, false aneurysms, AV fistula)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e18 (4.1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePericardial effusion (haemodynamically relevant requiring pericardiocentesis)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4 (0.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGastroparesis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (0.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCPR because of hypoxia under anaesthetic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (0.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHaematemesis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (0.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProcedure related haemoptysis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (0.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProcedure related death (respiratory insufficiency)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (0.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMinor complications\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePericardial effusion (haemodynamically not relevant)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (1.6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOesophageal ulceration\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eValues are n (%)\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eAV, arteriovenous\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eIncidence of AKI\u003c/h2\u003e \u003cp\u003eSCr level after catheter ablation was measured in all 444 patients. The overall incidence of AKI recorded after CB2-based PVI was very low (2.9%). As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e2\u003c/span\u003e, most patients who developed AKI were in the CKD stage 4 group (2/7, 28.6%), followed by CKD stage 3 (7/111; 6.3%), CKD stage 1( 1/70; 1.4%) and CKD stage 2 (3/256; 1.2%). Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows an alluvial diagram illustrating the alteration of kidney function according to eGFR from baseline to 48 hours of follow-up. The height of each stream represents the proportion of patients. Some patients eventually progressed to a higher CKD stage without meeting the criteria for AKI.\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows the comparison of baseline demographic and procedural characteristics between the AKI and non-AKI groups. The groups were unevenly distributed due to the low incidence of postcontrast AKI. However, significant differences were found in the incidence of arterial hypertension (AKI 92%, non-AKI 65%, p\u0026thinsp;=\u0026thinsp;0.041), HASBLED score (AKI 2.38\u0026thinsp;\u0026plusmn;\u0026thinsp;1, non-AKI 1.74\u0026thinsp;\u0026plusmn;\u0026thinsp;1, p\u0026thinsp;=\u0026thinsp;0.041), rhythm at the beginning of the procedure (AKI 69%, non-AKI 36%, p\u0026thinsp;=\u0026thinsp;0.019), baseline creatinine (AKI 1.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.62, non-AKI 1.01\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28, p\u0026thinsp;=\u0026thinsp;0.002), complication rate (AKI 42%, non-AKI 9%, p\u0026thinsp;=\u0026thinsp;0.001) and BW- and baseline SCr-adjusted maximum CM dose (CM \u0026times; SCr/BW) (AKI 2.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4, non-AKI 1.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6; p\u0026thinsp;=\u0026thinsp;0.027). The notion that the relationship between AKI and the adjusted CM dose may also be threshold-dependent was explored by using a cut-off of 2.7 proposed by Yamamoto et al\u003csup\u003e29\u003c/sup\u003e. Patients exceeding the threshold of 2.7 were more common in the AKI-group than in the non-AKI cohort (23% vs 4%; p\u0026thinsp;=\u0026thinsp;0.017). A multivariate analysis was performed to determine predicting baseline characteristics for AKI after catheter ablation. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, baseline CKD stage (HR 1.3659, 95% CI 0.05107\u0026ndash;36.53, p\u0026thinsp;=\u0026thinsp;0.033) was identified as an independent predictor of AKI. However, individuals with type 2 diabetes were highly underrepresented in our study group. Hence, conclusions on the effects of type 2 diabetes on postcontrast AKI is limited.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of baseline demographic and procedural characteristics between the AKI and non-AKI group\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNon-AKI\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;431)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAKI\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;13)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge [years.]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e66\u0026thinsp;\u0026plusmn;\u0026thinsp;10.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e70\u0026thinsp;\u0026plusmn;\u0026thinsp;10.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.082\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale sex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e234 (54%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9 (69%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.399\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI [kg/m\u0026sup2;]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.822\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAF type (persistent AF), [%]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e201 (47%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7 (54%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.779\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eEchocardiographic data\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLA diameter [mm]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e44\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.333\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLVEF [%]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59\u0026thinsp;\u0026plusmn;\u0026thinsp;9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e57\u0026thinsp;\u0026plusmn;\u0026thinsp;14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.696\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eComorbidities\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eArt. Hypertension\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e280 (65%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12 (92%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.041\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiabetes mellitus\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e54 (13%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (13%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeart failure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42 (10%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (15%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.375\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCoronary artery disease\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30 (1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.064\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStroke, TIA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e36 (8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (15%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.307\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCHA2DS2-VASc score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.15\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.483\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHASBLED score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.74\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.38\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.041\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRenal function\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBaseline creatinine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.01\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAblation procedure\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRhythm at start [AF]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e154 (36%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9 (69%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.019\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProcedure duration [mins]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e94.56\u0026thinsp;\u0026plusmn;\u0026thinsp;35.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e97.08\u0026thinsp;\u0026plusmn;\u0026thinsp;46.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.968\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFluoroscopy duration [mins]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19.27\u0026thinsp;\u0026plusmn;\u0026thinsp;8.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.54\u0026thinsp;\u0026plusmn;\u0026thinsp;10.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.098\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFluoroscopy dosage [cGy*cm\u0026sup2;]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2760\u0026thinsp;\u0026plusmn;\u0026thinsp;3404\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3193\u0026thinsp;\u0026plusmn;\u0026thinsp;2605\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.241\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eContrast medium [ml]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e126\u0026thinsp;\u0026plusmn;\u0026thinsp;41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e132\u0026thinsp;\u0026plusmn;\u0026thinsp;54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.472\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBodyweight-adapted CM volume [ml/kg]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.51\u0026thinsp;\u0026plusmn;\u0026thinsp;0.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.65\u0026thinsp;\u0026plusmn;\u0026thinsp;0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.664\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCM \u0026times; SCr/BW ratio\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1,5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.027\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCM \u0026times; SCr/BW ratio\u0026thinsp;\u0026gt;\u0026thinsp;2.7,\u0026nbsp;n\u0026nbsp;(%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17 (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.017\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComplications\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e39 (9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (42%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eThe data are presented as number (%) or mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eCKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; LVEF, left ventricular ejection fraction; LA, left atrium; AF, atrial fibrillation. BMI, body-mass-index; TIA, transient ischemic attack\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLogistic regression model for analysis of AKI predictors\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOdds ratio (95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.0220 (0.92766\u0026ndash;1.13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.664\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4.4666 (0.83970\u0026ndash;23.76)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.726\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePersistent AF (vs paroxysmal)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.0235 (0.27907\u0026ndash;3.75)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.803\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.9519 (0.76400\u0026ndash;1.19)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.666\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistory of heart failure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.7884 (0.10741\u0026ndash;5.79)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.817\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiabetes mellitus\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6.0568 (0.44745\u0026ndash;81.99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.121\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eArterial hypertension\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.2245 (0.02072\u0026ndash;2.43)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.170\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHASBLED score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.7309 (0.25794\u0026ndash;2.07)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.555\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCHA2DS2-Vasc score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.9334 (0.40493\u0026ndash;2.15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.872\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBaseline CKD stage\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.3659 (0.05107\u0026ndash;36.53)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.033\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVolume of contrast medium\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.0231 (0.97863\u0026ndash;1.07)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.309\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBodyweight-adapted CM volume\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.1469 (0.00696\u0026ndash;3.10)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.231\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFluoroscopy duration\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.9341 (0.86638\u0026ndash;1.01)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.087\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003eCI, confidence interval; AF, atrial fibrillation; LVEF, left ventricular ejection fraction; and eGFR, estimated glomerular filtration rate. BMI, body-mass-index\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe present large retrospective study reporting on the incidence of postprocedural AKI in second-generation cryoballoon-based PVI has two main findings.\u0026nbsp;\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eFirst, the overall incidence of AKI was very low (2.9%) and demonstrates the overestimation of the risk of contrast-associated AKI.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eSecond, patients with CKD stage 4 and arterial hypertension have the highest risk of developing AKI.\u0026nbsp;\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eContrast-associated AKI is a serious complication resulting from the administration of contrast media during cryoballoon-based PVI and is therefore considered a limitation for this otherwise successful treatment option\u003csup\u003e11\u003c/sup\u003e. In the past, many studies have been conducted on the incidence of AKI in patients undergoing interventional procedures, with rates reported between 0% and 21% depending on different factors such as comorbidities, type of procedure, definition of AKI, and time of post-contrast serum creatinine measurement\u003csup\u003e12,13,14;15\u003c/sup\u003e. It is well known that preexisting impaired renal function is a risk factor and progressive decline in renal function can be precipitated by contrast media administration\u003csup\u003e13,16\u003c/sup\u003e. However, little is known about its significance in clinical practice due to the lack of specific data from a large patient cohort who underwent CB ablation.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn the present study, the overall incidence of AKI was very low and has been exaggerated in clinical practice. In view of these data there appears to be no evidence to categorically withhold contrast media based on kidney function. If contrast media administration is clinically indicated, consideration should be given to potential risks and benefits as well as alternative imaging strategies \u003csup\u003e17, 22\u003c/sup\u003e. An association between contrast volume and AKI has been previously addressed in several reports. In a study by Brown and his colleagues with 10,065 patients undergoing PCI, they reported an increased risk of AKI in patients exposed to higher doses of contrast media than in those who received lower doses\u003csup\u003e21\u003c/sup\u003e. The present study also demonstrates an association between AKI and CM dose calculated by CM \u0026times; SCr/BW. The notion that the relationship between these two variables may also be threshold-dependent was confirmed by using a cut-off of 2.7 proposed by Yamamoto et al\u003csup\u003e29\u003c/sup\u003e. A learning curve with the second-generation cryoballoon technique was observed regarding procedure time and fluoroscopy time, but not in use of contrast media volume and complication rate.\u003c/p\u003e\n\u003cp\u003eOur data also show an association between AKI and periinterventional complications, already described in previous studies\u003csup\u003e29,30\u003c/sup\u003e.\u0026nbsp;Szegedi et al. found an association between pre-existing conditions such as hypertension and higher CHA2DS2-VASc score with a higher risk for procedure-related adverse events\u003csup\u003e31\u003c/sup\u003e. In the present study, the prevalence of arterial hypertension, the CHADS VASC score and the HAS BLED score were higher in the AKI group than in the non-AKI group. Existing literature has reported an increased \u0026nbsp; risk of AKI in patients with comorbidities\u003csup\u003e13,16,18,19\u003c/sup\u003e. It is well known that high systolic blood pressure is a risk factor for AKI due to the impairment the normal functioning of renal blood vessels\u003csup\u003e23\u003c/sup\u003e. As a result, especially patients with preexisting impaired renal function become more vulnerable to the effects of contrast media\u003csup\u003e24\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003ePostprocedural AKI also has significant prognostic implications for patients\u0026nbsp;after cryoballoon ablation. An association between impaired renal function and the recurrence of AF has been reported by Yanagisawa et al. The study with 110 patients who underwent second-generation cryoballoon catheter ablation demonstrated that patients with CKD stage 3 (eGFR 30\u0026ndash;59.9 mL/min/1.73 m\u0026sup2;) had significantly worse prognosis than patients in other CKD stages. Moreover, CKD stage 3 was associated with a higher recurrence rate and was identified as an independent predictor of recurrence. AF recurrence after PVI requires multiple procedures to maintain sinus rhythm and leads to a relevant impairment of long-term success\u003csup\u003e27\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn the present study, baseline CKD stage was identified as an independent predictor of AKI. Of note, it is also relevant to know which CKD stage is at increased risk of deterioration in renal function. We found that the prevalence of AKI was high in CKD stage 4. . According to the guidelines of the American College of Radiology and the National Kidney Foundation regarding the administration of an iodine-based contrast agent, patients with an eGFR less than 30 mL/min/1.73m\u0026sup2; prior to contrast agent administration are at a potential risk of AKI \u003csup\u003e17\u003c/sup\u003e. Hence, preventive measures such as hydration and contrast media dose reduction are necessary for patients at risk following guidelines\u0026rsquo; recommendation\u003csup\u003e25, 26\u003c/sup\u003e. Alternative techniques available for verifying pulmonary vein occlusion without the use of contrast media include occlusion tool software, saline injection-based occlusion tools, or direct pressure monitoring and should be strongly considered\u003csup\u003e32, 33, 34\u003c/sup\u003e.\u003c/p\u003e\n\u003ch1\u003eLimitations\u003c/h1\u003e\n\u003cp\u003eThe current study is a retrospective, monocentric analysis with limitations ascribed to such type of design. Neither the pre- and post-procedural fluid intake nor the administration of nephrotoxic medication were consistently documented. Such documentation would have been desirable, as adequate hydration can reduce the risk of post-contrast ANV and some medications can promote the deterioration in renal function. Also, due to the low incidence of post-contrast AKI, the statistical analysis of independent predictors was limited and a conclusion about the impact on contrast AKI is difficult.\u0026nbsp;\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eOur study demonstrates that cryoballoon ablations are associated with a low incidence of acute renal injury, indicating their relative safety in terms of immediate renal impacts. Patients with CKD stages 1 and 2 were less affected by acute kidney injury following cryoablation. These findings demonstrate that cryoablation PVI is a safe therapeutic option for individuals with CKD stages 1 and 2 without significant risk of AKI. However, a contrasting trend is observed in patients with CKD stages 3 and 4. In this subset of patients, cryoablations are linked with an increased incidence of adverse renal events. The increased risk should be considered in when planning an ablation. Our findings advocate a more cautious approach in this vulnerable patients and for the consideration of using alternative ablation techniques without the use of contrast media in this patient demographic to mitigate the risk of further deterioration in renal function.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cu\u003eAuthor contributions\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCL\u0026nbsp;\u003c/strong\u003econceived and designed the study. She also provided critical revisions and approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePH\u003c/strong\u003e was responsible for data collection and management. He conducted the primary statistical analyses and wrote the initial draft of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLR,\u003c/strong\u003e \u003cstrong\u003eSM\u003c/strong\u003e,\u003cstrong\u003e\u0026nbsp;FO\u003c/strong\u003e and \u003cstrong\u003eTM\u003c/strong\u003e contributed to the data analysis and interpretation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePW and MS\u003c/strong\u003e supported the statistical analysis of the data\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAM, KHK, CHH\u003c/strong\u003e and \u003cstrong\u003eBR\u0026nbsp;\u003c/strong\u003esupervised the project, contributed to the study design, and provided important intellectual content.\u003c/p\u003e\n\u003cp\u003eAll authors have approved the submitted version.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cu\u003eAvailability of Data and Materials\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cu\u003eAdditional Information\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eSchnabel RB, Wilde S, Wild PS, M\u0026uuml;nzel T, Blankenberg S. 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Radiology 2010;256:21\u0026ndash;28. \u003c/li\u003e\n\u003cli\u003eDylewska M, Chomicka I, Małyszko J. Hypertension in patients with acute kidney injury. Wiad Lek. 2019;72(11 cz 2):2199-2201. \u003c/li\u003e\n\u003cli\u003eLun Z, Mai Z, Liu L, Chen G, Li H, Ying M, Wang B, Chen S, Yang Y, Liu J, Chen J, Ye J, Liu Y. Hypertension as a Risk Factor for Contrast-Associated Acute Kidney Injury: A Meta-Analysis Including 2,830,338 Patients. Kidney Blood Press Res. 2021;46:670-692.\u003c/li\u003e\n\u003cli\u003eStacul F, van der Molen AJ, Reimer P, Webb JA, Thomsen HS, Morcos SK, Almen T, Aspelin P, Bellin MF, Clement O, Heinz-Peer G. Contrast induced nephropathy: updated ESUR Contrast Media Safety Committee guidelines. Eur Radiol 2011;12:2527\u0026ndash;2541.\u003c/li\u003e\n\u003cli\u003eSeeliger E, Becker K, Ladwig M, Wronski T, Persson PB, Flemming B. Up to 50-fold increase in urine viscosity with iso-osmolar contrast media in the rat. 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Europace 2012;14:528-606. \u003c/li\u003e\n\u003cli\u003eYamamoto M, Hayashida K, Mouillet G, Chevalier B, Meguro K, Watanabe Y, Dubois-Rande JL, Morice MC, Lef\u0026egrave;vre T, Teiger E. Renal function-based contrast dosing predicts acute kidney injury following transcatheter aortic valve implantation. JACC Cardiovasc Interv. 2013 May;6(5):479-86.\u003c/li\u003e\n\u003cli\u003eJames MT, Ghali WA, Knudtson ML, Ravani P, Tonelli M, Faris P, Pannu N, Manns BJ, Klarenbach SW, Hemmelgarn BR; Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) Investigators. Associations between acute kidney injury and cardiovascular and renal outcomes after coronary angiography. Circulation. 2011 Feb 1;123(4):409-16.\u003c/li\u003e\n\u003cli\u003eSzegedi N, Sz\u0026eacute;plaki G, Herczeg S, Tahin T, Sall\u0026oacute; Z, Nagy VK, Osztheimer I, \u0026Ouml;zcan EE, Merkely B, Gell\u0026eacute;r L. Repeat procedure is a new independent predictor of complications of atrial fibrillation ablation. Europace. 2019 May 1;21(5):732-737.\u003c/li\u003e\n\u003cli\u003eCauti FM, Rossi P, Polselli M, Iaia L, Giannitti CM, Bianchi S. Occlusion tool software for pulmonary vein occlusion verification in atrial fibrillation cryoballoon ablation to avoid the use of contrast injection. HeartRhythm Case Rep. 2020 May 23;6(8):516-519. \u003c/li\u003e\n\u003cli\u003eRottner L, Obergassel J, Borof K, My I, Moser F, Lemoine M, Wenzel JP, Kirchhof P, Ouyang F, Reissmann B, Metzner A, Rillig A. A novel saline-based occlusion tool allows for dye-less cryoballoon-based pulmonary vein isolation and fluoroscopy reduction. Front Cardiovasc Med. 2023 Mar 24;10:1156500. \u003c/li\u003e\n\u003cli\u003eSunaga A, Masuda M, Asai M, Iida O, Okamoto S, Ishihara T, Nanto K, Kanda T, Tsujimura T, Matsuda Y, Okuno S, Mano T. Pressure monitoring predicts pulmonary vein occlusion in cryoballoon ablation. J Interv Card Electrophysiol. 2018 Oct;53(1):115-121.\u003c/li\u003e\n\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":"Atrial fibrillation, cryoballoon catheter ablation, estimated glomerular filtration rate, pulmonary vein isolation, contrast-induced nephropathy","lastPublishedDoi":"10.21203/rs.3.rs-4592833/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4592833/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e - An effective treatment of symptomatic Atrial fibrillation (AF) is the second-generation cryoballoon (CB2) based pulmonary vein isolation (PVI). However, this technique is associated with an increased exposure to contrast media and little is known about postprocedural acute kidney injury (AKI).\u003c/p\u003e\n\u003cp\u003eObjective - We evaluated the incidence, characteristics and risk factors of contrast-associated AKI after CB2-based catheter ablation in a large patient cohort.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e - 444 patients with symptomatic drug-refractory paroxysmal AF (PAF, n=236 [53%]) or persistent AF (n=208) who underwent CB2-based PVI were included. The study group was divided into four groups based on the estimated glomerular filtration rate (eGFR) documented the day before the procedure. Serum creatinine levels were measured before and 48 hours after the procedure. AKI was assessed using the KDIGO guidelines.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults \u003c/strong\u003e- The overall incidence of AKI was 2.9% (13/444). Among the AKI group, the majority were in CKD stage 4 (2/7, 28.6%), followed by CKD stage 3 (7/111; 6.3%), CKD stage 1(1/70; 1.4%) and CKD stage 2 (3/256; 1.2%). Baseline CKD stage (HR 1.3659, 95% CI 0.05107 - 36.53, p = 0.033) was identified as independent predictor of AKI. Arterial hypertension was prevalent in the AKI group.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e - The overall incidence of postcontrast AKI in CB2-based ablation of AF was low. Cryoablation PVI is a safe therapeutic option for individuals with CKD stages 1 and 2. However, in patients with CKD stages 3 and 4, it is associated with an increased incidence of AKI.\u003c/p\u003e","manuscriptTitle":"Contrast-associated acute kidney injury in second-generation cryoballoon-based pulmonary vein isolation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-18 22:19:05","doi":"10.21203/rs.3.rs-4592833/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":"baeef7ac-0188-4caa-936e-d52bd9e22d82","owner":[],"postedDate":"July 18th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":34446090,"name":"Health sciences/Nephrology/Kidney diseases"},{"id":34446091,"name":"Health sciences/Cardiology"}],"tags":[],"updatedAt":"2024-12-20T04:53:58+00:00","versionOfRecord":[],"versionCreatedAt":"2024-07-18 22:19:05","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4592833","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4592833","identity":"rs-4592833","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}