Association of Global Longitudinal Strain and Long-Term Transplant-Free Survival in Fontan Patients

Association of Global Longitudinal Strain and Long-Term Transplant-Free Survival in Fontan Patients | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL Echocardiography This is a preprint and has not been peer reviewed. Data may be preliminary. 18 June 2025 V1 Latest version Share on Association of Global Longitudinal Strain and Long-Term Transplant-Free Survival in Fontan Patients Authors : Assami Rosner 0000-0001-9084-5805 [email protected] , Simone Goa Diab , Mark Friedberg , and George Lui Authors Info & Affiliations https://doi.org/10.22541/au.175027876.67071873/v1 Published Echocardiography Version of record Peer review timeline 222 views 215 downloads Contents Abstract Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Background and objectives: Patients with single-ventricle physiology undergoing Fontan operations face high morbidity and mortality risks. While classic-pattern dyssynchrony (CPD) and protein-losing enteropathy (PLE) are known predictors of adverse outcomes, the role of global longitudinal strain (GLS) as an independent predictor of heart failure remains unclear. Methods: A retrospective cohort study of 135 Fontan-operated patients from 2014-2015 evaluated the predictive value of GLS alongside PLE and CPD on mortality and transplantation after 9 years. Echocardiographic data, including GLS, were analyzed using speckle tracking strain analysis in 132 patients. The primary endpoint was transplant-free survival. Results: Among 132 Fontan patients, 15 had classic-pattern dyssynchrony, 29 had protein-losing enteropathy, 37 had moderately reduced global longitudinal strain (GLS <-8% ≥-16%), and 18 had severely reduced GLS (≥-8%). Cox regression analysis showed moderately reduced GLS increased mortality risk (HR 5.8, 95% CI 1.27-26.5, p=0.023), with severely reduced GLS showing an HR of 10.3 (95% CI 2.18-48.6, p=0.003). These results were comparable to CPD (HR 11.5, p=0.002) and PLE (HR 14.9, p<0.001). Conclusion: Global longitudinal strain emerged as the best independent factor for predicting long-term transplant-free survival in Fontan patients, highlighting the importance of GLS assessment in routine follow-up to identify high-risk individuals for early intervention. Association of Global Longitudinal Strain and Long-Term Transplant-Free Survival in Fontan Patients Assami Rösner, MD, PhD 1,2 ; Simone Goa Diab, MD 3,4 ; Mark K Friedberg, MD, PhD 5 ; George K Lui, MD 6,7 1 Department of Cardiology, Division of Cardiothoracic and Respiratory Medicine, University Hospital of North Norway, Norway 2 Department of Clinical Medicine (IKM), UiT The Arctic University of Norway 3 Department of Paediatric Cardiology, Oslo University Hospital Rikshospitalet, Oslo, Norway 4 Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo Norway 5 Division of Pediatric Cardiology, Labatt Family Heart Center, Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada 6 Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA 7 Division of Pediatric Cardiology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA Contact: Assami Rösner, MD, PhD Department of Cardiology, Division of Cardiothoracic and Respiratory Medicine, University Hospital of North Norway And Department of Clinical Medicine (IKM) UiT The Arctic University of Norway 9038 Tromsø, Norway Tel: +47 77627347 e-mail: [email protected] Assami Rösner received a grant by Helse Nord HNF 1342-17 Conflicts of Interest: Nothing to Disclose. Global Longitudinal Strain emerges as critical predictor of long-term survival of Fontan patients. This echocardiographic parameter can identify high-risk patients early, potentially transforming cardiac follow-up strategies. #CardiacResearch #Cardiology Abstract Background and objectives: Patients with single-ventricle physiology undergoing Fontan operations face high morbidity and mortality risks. While classic-pattern dyssynchrony (CPD) and protein-losing enteropathy (PLE) are known predictors of adverse outcomes, the role of global longitudinal strain (GLS) as an independent predictor of heart failure remains unclear. Methods: A retrospective cohort study of 135 Fontan-operated patients from 2014-2015 evaluated the predictive value of GLS alongside PLE and CPD on mortality and transplantation after 9 years. Echocardiographic data, including GLS, were analyzed using speckle tracking strain analysis in 132 patients. The primary endpoint was transplant-free survival. Results: Among 132 Fontan patients, 15 had classic-pattern dyssynchrony, 29 had protein-losing enteropathy, 37 had moderately reduced global longitudinal strain (GLS <-8% ≥-16%), and 18 had severely reduced GLS (≥-8%). Cox regression analysis showed moderately reduced GLS increased mortality risk (HR 5.8, 95% CI 1.27-26.5, p=0.023), with severely reduced GLS showing an HR of 10.3 (95% CI 2.18-48.6, p=0.003). These results were comparable to CPD (HR 11.5, p=0.002) and PLE (HR 14.9, p<0.001). Conclusion: Global longitudinal strain emerged as the best independent factor for predicting long-term transplant-free survival in Fontan patients, highlighting the importance of GLS assessment in routine follow-up to identify high-risk individuals for early intervention. Keywords: Univentricular hearts, transplantfree survival, heart-failure, Fontan Fontan operation Strain rate imaging Global longitudinal strain Prediction of Long-term survival Competing interests: none List of Abbreviations AV: atrioventricular BV: biventricular BP: blood pressure BMI: body mass index CPD: Classic Pattern Dyssynchrony EF: ejection fraction GCS: global circumferential strain GCSR: global circuferential strain rate GLS: global longitudinal strain GLSR: global longitudinal strain rate LVOT left ventricular outflow tract PLE: protein losing enteropathy UVH: univentricular hearts VTI: velocity time integral SR: strain rate SV: single ventricle -S: systolic -E: early diastolic Introduction Patients with single-ventricle physiology undergoing the Fontan operation face significant long-term challenges, including high risks of morbidity and mortality. Despite advancements in surgical techniques and medical care, these patients still encounter complications that require advanced management and continuous monitoring(1-5). Survival rates in the Australia and New Zealand Fontan Registry are reduced to 75% at 25 years, emphasizing the need for continuous monitoring and intervention strategies(6). Identification of the most important risk factors and their impact on patient outcomes is crucial for developing effective management strategies. Echocardiographic assessment is essential in managing patients with Fontan circulation, providing detailed insights into cardiac function and hemodynamics. In a previous study on a Fontan patient cohort, we investigated echocardiographic and clinical parameters indicating 5-10 years of transplant-free survival, particularly focusing on the importance of classic pattern dyssynchrony (CPD)(7). In the heterogeneous group of congenital heart disease, identification of CPD and global longitudinal strain (GLS) has emerged as a significant predictor of adverse outcomes, including mortality and transplantations (8-10). Some studies on patients with Fontan circulation have indicated that GLS might also be a mortality-risk factor comparable to CPD and protein-losing enteropathy (PLE) in the Fontan population (7, 10, 11). Despite the significant progress made in understanding the role of cardiac functional parameters in predicting the outcomes of patients with Fontan circulation, several factors remain unknown. One of the primary uncertainties is the role of GLS as a predictor of long-term outcomes. Additionally, the optimal thresholds for GLS that most accurately predict adverse outcomes have not been firmly established. Furthermore, little is known about cardiac strain rate imaging in high-risk patients such as those with PLE. This study aims to investigate the role of strain and strain rate (SR) and conventional echocardiographic parameters in predicting adverse long-term outcomes in Fontan patients after a 4-5 years longer follow-up period than the first outcome-study. Specifically, it seeks to determine whether GLS can serve as an independent predictor of mortality and transplantation, alongside established risk factors such as CPD and PLE. Additionally, the study aims to explore the combined effects of these risk factors on patient outcomes and to describe cardiac function in the PLE group with and the association to risk for transplantation or death. Study Design and Population This retrospective cohort study was conducted at Lucile Packard Children’s Hospital and the Adult Congenital Heart Program at Stanford University. A total of 135 patients who had undergone the Fontan procedure were included in the study, all of whom 132 had available echocardiographic data and clinical follow-up records, without exclusion criteria. In 3 out of the 135 patients, no echocardiography with ventricular images was performed. The study’s primary endpoint was transplantation or death assessed in May 2024, thus prolonging the study follow-up period of the previous publication (7) by 4 years. Cardiac morphology data were extracted from patient medical records. The univentricular heart (UVH) distribution was categorized based on morphological characteristics, including the presence of two sizable ventricular components (biventricular, BV), a dominant right ventricle, or a dominant left or single ventricle (SV). When the ventricular anatomy was not clearly defined as right, left, or BV, the echocardiographic images were re-evaluated. Hearts that could not be definitively categorized were classified as having ”undefined” SV anatomy. Additional clinical data such as electrocardiogram (ECG) results, blood pressure (BP), height, weight, body mass index (BMI), New York Heart Association (NYHA) functional class, and the presence of PLE were obtained from the records, corresponding to the date of the echocardiogram or the closest available date. Patients were categorized into three main groups: Patients with PLE, Patients without PLE, Patients with CPD and Patients without PLE or CPD. The latter group was then further categorized according to global longitudinal strain values, as described below. Data Collection and Echocardiographic Analysis Echocardiographic data were collected from patient records between 2001 and 2015, utilizing Philips iE33 and Siemens Acuson ultrasound systems at the participating institutions. Following institutional protocols, images included apical and short-axis views, which allowed for the assessment of ventricular geometry, and strain rate imaging. Data such as ejection fraction (EF), atrioventricular (AV) valve regurgitation grades, and ventricular volumes were obtained using standard methods. Systolic and diastolic ventricular volumes and EF were calculated using the single-view Simpson method based on endocardial traces from a two-dimensional apical loop. The echocardiographic analysis also included an assessment of diastolic function using atrioventricular valve Doppler recordings, measuring E-wave and A-wave velocities, E-wave deceleration time (DT), and E/A ratio. Further analysis involved calculating the E/e’ ratio, which was derived from basal speckle-tracking displacement velocities. Two-Dimensional Speckle-Tracking Analysis for Strain and Strain Rate Strain and SR were evaluated offline using two-dimensional speckle-tracking analysis, focusing on apical “four-chamber” views and mid-ventricular short-axis views. The analysis was performed using 2D Cardiac Performance Analysis software (TomTec Imaging Systems, Unterschleissheim, Germany) for data from Philips Ultrasound systems and syngo Velocity Vector Imaging software (Siemens Medical Solutions USA, Mountain View, CA) for data from Siemens Ultrasound systems, which both utilized the identical tracking algorithms from TomTec in 2014/15, when the strain analysis was performed, ensuring consistency in the extraction of values from the strain curves. The images were captured at an average frame rate of 40 ± 12 frames per second, with a range of 30 to 93 frames per second. For the analysis, mid-myocardial traces were used to generate longitudinal and circumferential strain and strain rate (SR) curves. Each ventricular projection was divided into six segments, focusing on the septum and lateral wall in cases where the septum was intact, and excluding the lateral wall of hypoplastic ventricles. For patients with single-ventricle or large VSD, strain measurements were taken from the outer ventricular walls, excluding any residual septum. Strain curves with missing segments or poor-quality tracking were excluded from the analysis. Timing measurements for aortic valve opening and closure, AV valve opening, E-wave termination, and AV valve closure were recorded based on Doppler flow patterns, with the R wave on the electrocardiogram used as a reference point for the onset of the cardiac cycle. Customized software (using an Excel macro, Microsoft, Redmond, WA) was employed to extract peak positive and negative strain values during systole, as well as diastolic SR and basal velocities during the E waves. Based on ROC curve analysis for death and transplantation, GLS, measured as the peak systolic value, was stratified into three categories: GLS (better than) ≥ -16%; GLS between > -8% and <-16%; and GLS (worse than) ≥ -8%. CPD was identified through a visual assessment of specific strain patterns as seen in long-axis and short-axis views, with the presence of early activated segments showing early shortening (flash) followed by a rebound stretch, while opposite segments show early stretch and delayed shortening. These patterns were validated in a previously published framework for identifying dyssynchrony in single-ventricle physiology (7, 12). As described in previous literature, CPD is analogous to the dyssynchrony seen in patients with left bundle branch block (LBBB) (12). Statistical Analysis Data were presented as means with standard deviations (mean ± SD) or as proportions, depending on the nature of the variable. ROC curve analysis was used to identify optimal GLS cut-off points for the definition of the functional GLS groups, ensuring at least 80% specificity or sensitivity for the outcome. Chi-square tests were utilized for comparing proportions, while ANOVA with Bonferoni post-hoc tests were used for analyzing differences between continuous variables. The primary endpoint, death or transplant, was analyzed using multivariate Cox proportional hazards regression models. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for each functional parameter and for the five defined patient groups, i.e. three GLS groups patients with PLE and with CPD. Survival curves were constructed using the Kaplan-Meier method. Ethical Considerations The study was approved by the institutional review boards. All procedures adhered to institutional human subjects committee guidelines. Results In this cohort of 135 patients with Fontan circulation, we identified several key echocardiographic parameters and clinical characteristics that were significantly associated with risk for transplant or death. The median age at echocardiography was 20.5 years, with a range from 3 to 45 years (Table 1). The majority of patients at risk (66.7 %) were male. Patients were younger at the date of echocardiography due to inclusion of the last available echocardiogram. About half of the patients at risk had either PLE or CPD. Furthermore, death and transplantation was associated with low systolic blood pressure, biventricular anatomy, low EF and GLS. Ventricular function and GLS As demonstrated in Table 2, significant differences between transplant-free survivors and death and/or transplant groups were found in various echocardiographic functional parameters across the GLS, and CPD groups. Non-survivors in the CPD group showed significantly higher ventricular systolic and diastolic volumes, and heart rate, and lower EF, GLS, global circumferential strain (GCS) and global systolic circumferential SR (GCSR S). Patients at risk in the group without CPD or PLE showed significantly lower EF GLS, global longitudinal SR (GLSR), GCS, GCSR and higher S/D ratio and AVV E/a ratio. In the group of patients with PLE only, diastolic blood-pressure was significantly lower in the group at risk, while there was a (not significant) tendency towards reduced systolic and diastolic myocardial function and elevated filling pressures. Transplant-Free Survival and Predictors of Adverse Outcomes Over a median follow-up period of 9.6 ± 5.6 years (median 10.0, quartile 5.9/12.4 years, 40 patients experienced the primary endpoint of death or transplantation, 25 patients were transplanted and survived, 15 patients died, and 4 patients were transplanted and died. Table 3 shows the distribution of survivors, death and transplant among the 5 groups. ROC curve analysis for death and/or transplant was conducted for EF, longitudinal GLS, GLSR S, GLSR E and circumferential GCS, GCSR S, and GCSR E. These analyses revealed comparable results across all investigated functional parameters, with all significant AUCs between 0.604 to 0.711. Among these parameters, GLS demonstrated the highest AUC at 0.711 (95% CI, 0.646-0.828; p<0.001). Due to its superior performance across all tests and its established clinical use, GLS was selected for grouping and for further analysis. The analysis stratified participants into groups based on two thresholds: a high sensitivity group at a GLS of -16% (sensitivity 85.0%; specificity 45%) and high specificity group at a GLS of -8% (specificity 86%, sensitivity of 45%). Survival analysis, shown in Table 4 and Figure 1, revealed that patients with GLS ≥ -8% had the poorest outcomes, with only 56% achieving transplant-free survival, compared to 94% in the GLS < -16% group. Survival after the date of echocardiogram is shown in Figure 2 with the associated Cox-regression analysis of Table 5. For both time-sequences after Fontan completion or echocardiogram, the presence of CPD and PLE were similarly associated with reduced survival, with transplant-free survival rates of 53% and 55%, respectively. Figure 3 shows the date of the last available echocardiogram (which also reflects the age of transplantation (Tx) or death) plotted against GLS, and aggregated by the presence or absence of PLE or CPD. None of the patients with CPD combined with low GLS were among the transplant-free survivors. Figure 3 highlights that death and transplantation due to CPD and PLE are more commonly observed in children. In contrast, severe and moderate reductions in GLS are linked to higher mortality rates later in life. Multivariate Cox regression analysis demonstrated in Table 4 that all systolic functional parameters in the univariate analysis were associated with death and transplant. However, all of those parameters were highly correlated with each other, not showing independent association with outcome in the multivariate analysis. GLS, EF and the diastolic GLSR E of all functional parameters were the strongest factors indicating transplantation and death. The correlation of CPD with GLS as predictors of transplant-free survival was too high to be used as independent predictors. and Table 5 identified GLS ≥ -8% as a significant independent predictor of adverse outcomes after the echocardiogram, with a hazard ratio (HR) of 10.3 (95% CI: 2.18 - 48.6, p = 0.003). CPD (HR 11.5, 95% CI: 2.39 - 55.6, p = 0.002) and PLE (HR 14.9, 95% CI: 3.32 - 66.4, p < 0.001) were also strong independent predictors. Interestingly, GLS between -8% and -16% was associated with an elevated risk of adverse outcomes (HR 5.8, 95% CI: 1.27 - 26.5, p = 0.023). not-yet-known not-yet-known not-yet-known unknown Discussion While overall long-term survival in patients with a Fontan circulation is good, there is a proportion who suffer from significant complications and decreased survival. The present study clearly identifies GLS (and other functional parameters) as an important independent predictor of death and transplantation in patients with Fontan circulation. Moreover, even moderate reductions in GLS (between -8% and -16%) were associated with a significantly increased risk for death and transplantation. Both CPD and PLE were strongly associated with reduced transplant-free survival in younger patients, particularly PLE. Patients with PLE displayed similar cardiac functional parameters comparing survivors and non-survivors and comparing to the overall Fontan population Additionally, our study revealed distinct age-related mortality risks: Transplantation and death due to PLE were more prevalent in children, CPD in adolescents, whereas severe and moderate GLS reductions were linked to higher mortality rates later in life. not-yet-known not-yet-known not-yet-known unknown GLS and Myocardial function and mortality There are relatively few studies on myocardial functional imaging and mortality in patients with Fontan surgery(10, 13, 14) and most of the studies investigated myocardial function by magnetic resonance imaging (MRI)(15-18). In our previous publication we showed CPD and PLE along with some diastolic parameters as the most prominent risk factors for transplantation or death (7). In all applied tests in this study including and excluding patients with PLE, GLS seemed to be the most distinct predictor for transplantation-free survival, and when analyzed as a function of time, the group with moderately reduced GLS also had significantly reduced survival, where GLS seemed to be a cause of death and transplantation in adulthood with a time-dependency on the severity of cardiac function. This study adds to a prior study of 127 Fontan patients which demonstrated an association between GLS and mortality/transplant in a younger population with shorter follow-up(17). Furthermore, CMR was used to examine the relationship of ventricular dyssynchrony and found a correlation with death and need for transplantation(15). Kramer et al. (19) studied 198 patients in a follow-up of 20.3 years and identified 25 deaths. This group suggested a multimodal score incorporating VO2 peak, NT-proBNP levels and the number of cardiovascular medications as the best predictors of a failing Fontan circulation. In that study, EF alone was found to be a relatively weak predictor of adverse outcomes, which aligns with the current study’s focus on GLS as a potentially more sensitive marker of long-term survival. The predictive value of GLS, particularly in the absence of PLE aligns with Kramer’s findings, suggesting that more detailed echocardiographic measures like GLS may provide superior prognostic information compared to traditional markers like EF. EF measurements in non-LV dominant single ventricles are additionally challenging, since reproducibility of non-ellipsoid shaped ventricles is probably low. not-yet-known not-yet-known not-yet-known unknown Transplant free survival Overall 10 year transplant free survival of this Fontan cohort was 70% which is primarily due to a highly selected patient population referred for transplantation at Stanford. The survival rates are comparable to the ones of the Mayo Clinic where post Fontan survival was 74% during the first 10 years after Fontan completion (20). Less selected national studies with younger patients showed survival rates of approximately 90 % after 10 years (6, 21). Multiple extracardiac risk factors in patients with Fontan circulation contribute to their increased mortality including non-extracardiac tunnel (4) thromboembolism (22), distorted pulmonary arteries, non-sinus rhythm (23), post-operative and prolonged pleural effusion (6), long cardiopulmonary bypass-time (24, 25). Poh et al performed a meta-analysis on 7536 patients and found 11% late deaths after a mean follow-up of 10 years. PLE, ventricular dysfunction and/or pacemaker were the most prominent predictors of mortality (3). This is consistent with the current study, which similarly found that patients with severely reduced GLS and PLE were at significantly higher risk for death and transplantation. Likewise, CPD essentially reflects the dyssynchronous activation-contraction that would be expected with pacing. In the study of Pundi et al., including 1052 patients with Fontan circulation, key factors associated with decreased survival included preoperative atrial arrhythmias, AV valve replacement at the time of Fontan surgery, PLE, ventricular arrhythmias and post-operative left atrial pressure greater than 13 mmHg as a surrogate of heart failure (20). Ohuchi et al.(2) also noted PLE as a risk factor for mortality in 600 Fontan survivors. Classic pattern dyssynchrony has been earlier identified as a risk factor for morbidity and mortality (7, 13, 15), which may also include pacemaker implantation as a risk factor for death and transplantation. These findings are comparable to those of the present study, where freedom from PLE, CPD and normal ventricular function assessed by GLS were significant predictors of transplant-free survival. GLS appeared to be a strong predictor of mortality in the CPD group with CPD patients exhibiting low GLS having higher mortality and transplantation rates during the first two decades of life. In our previous studies, we demonstrated that CPD in Fontan patients is often related to congenital branch blocks in larger biventricular hearts (12, 26), where high wall tension due to unfavorable anatomy may lead to early-onset ventricular failure. This hypothesis requires further investigation in future studies. The effect of moderately reduced GLS appears to be a previously underestimated predictor of mortality in adulthood where deteriorating ventricular function seems to constitute the primary risk factor. Myocardial function in PLE PLE is one of the most severe complications of the Fontan circulation, associated with high mortality rates (3, 20, 21). Detailed assessments of strain and strain-rate in PLE cohorts are not well known. Ohuchi et al(27) compared 26 patients with PLE to 56 Fontan survivors without risk factors, finding that CVP was initially elevated in PLE patients, though the difference disappeared by the time of diagnosis. Elevated central venous pressure (CVP) typically indicates heart failure; however, it has not been consistently demonstrated that patients with protein-losing enteropathy (PLE) following Fontan surgery show other markers of impaired ventricular function compared to non-PLE Fontan patients. In our study cohort, PLE was present at the time of echocardiography, irrespective of whether it was a new diagnosis of PLE or previously treated PLE. Lower diastolic blood pressure in the majority of PLE patients might suggest a reduced intravascular volume. We found no significant differences in parameters of systolic or diastolic heart function between transplant-free survivors and non-survivors. Notably, E-wave velocity was slightly, but not significantly higher in the non-survivors, potentially indicating elevated filling pressures. Additionally, non-survivors exhibited lower strain rate during early diastole (SR E) and higher E/e’ ratios, supporting the hypothesis of impaired relaxation combined with increased filling pressures. Systolic myocardial function, measured by global longitudinal strain (GLS), global circumferential strain (GCS), global longitudinal strain rate (GLSR), and global circumferential strain rate (GCSR), was slightly but not significantly reduced in non-survivors, suggesting a minor role for systolic and diastolic dysfunction in the mortality associated with this group. Clinical implications Regardless of whether studies investigated NT-proBNP levels (19, 28), NYHA class (2), postoperative catheter measurements (20), heart failure medications (20) or EF (3, 29), heart failure consistently emerged as one of the primary causes of death and transplantation in post-Fontan patients. GLS has proven to be a relatively simple and robust echocardiographic parameter for assessing cardiac function (30). Research on subclinical heart failure in patients with normal cardiac anatomy has demonstrated the high sensitivity of GLS in detecting a mild decrease in cardiac function (31). Although multiple cardiac function parameters have been identified as predictors of transplantation or death in the Fontan population, GLS and GLSR E were the only significant predictor in the multivariate analysis. However, GLS and EF are the only established measures, available in most of the high-end ultrasound systems. Overall, patients with normal GLS values showed excellent survival rates, indicating that GLS offers valuable prognostic information for long-term survival. These findings suggest that incorporating GLS into routine echocardiograms could significantly enhance the management and outcomes of patients with Fontan circulation not-yet-known not-yet-known not-yet-known unknown Limitations This study presents several limitations that should be considered when interpreting the findings. First, it is a retrospective cohort study with prospective 10 year follow-up data, leading to incomplete data, and potential loss of follow-up information. Given that the study population consists of patients treated at a highly specialized and transplant referral center, the findings may not be fully generalizable to broader Fontan populations with less complex cases or in less specialized clinical settings. Second, the study cohort is relatively small, consisting of 132 patients, which limits the statistical power of the analysis, however, the high number of death and transplant is comparable to other studies including 400 patients with an unfavorable outcome in 10%. The cohort’s heterogeneity, including a wide age range and varying severity of conditions like protein-losing enteropathy (PLE) and classic-pattern dyssynchrony (CPD), adds complexity to the analysis and may affect the robustness of the findings. Additionally, the study’s echocardiographic data were obtained using two different imaging platforms, Philips iE33 and Siemens Acuson ultrasound systems where earlier Acuson images provided lower frame rates. However, in 2014 the Tomtec (for Philips) and Siemens speckle tracking software, were based on the same analyzing algorithms developed by Tomtec. While speckle-tracking analysis is a well-established method for assessing global longitudinal strain (GLS), it is subject to technical limitations, especially in the retrospective setting, related to image resolution, frame rates, which could impact the precision of strain measurements. The term GLS usually refers to three projections. We decided not to change the term even though we only refer to results on one view with only 6 out of 16 myocardial segments. Finally, the study’s follow-up period, although median 10 years, included significant variations in follow-up times between patients. This variability could influence the outcomes, particularly when considering long-term survival and the time-dependent development of complications like late ventricular dysfunction and arrhythmias. The absence of consistent data on certain relevant clinical parameters, such as atrial arrhythmias, limits the ability to fully explore their role as potential confounders or mediators of the outcomes. Similarly, while GLS was identified as an important predictor, its optimal cutoff values for clinical use remain uncertain, and further studies are needed to validate these thresholds in larger, more diverse populations. not-yet-known not-yet-known not-yet-known unknown Conclusion This study confirms the importance of systolic functional parameters, especially GLS as an independent predictor of long-term survival and transplant-free survival in patients with Fontan circulation, particularly in those patients without PLE. GLS provides valuable insights into cardiac function, helping identify high-risk individuals for adverse outcomes. While cardiac function plays a lesser role in established PLE cases, GLS is potentially a key tool for risk stratification in the broader Fontan population, emphasizing its potential role in routine clinical management. References: 1. Gewillig M, Brown SC. The Fontan circulation after 45 years: update in physiology. Heart. 2016;102(14):1081-6.2. Ohuchi H, Inai K, Nakamura M, Park IS, Watanabe M, Hiroshi O, et al. Mode of death and predictors of mortality in adult Fontan survivors: A Japanese multicenter observational study. Int J Cardiol. 2019;276:74-80.3. Poh CL, d’Udekem Y. Life After Surviving Fontan Surgery: A Meta-Analysis of the Incidence and Predictors of Late Death. Heart Lung Circ. 2018;27(5):552-9.4. Polat AB, Erturk M, Uzunhan O, Karademir N, Oztarhan K. 27 years of experience with the Fontan procedure: characteristics and clinical outcomes of children in a tertiary referral hospital. J Cardiothorac Surg. 2023;18(1):38.5. Schamroth Pravda N, Richter I, Blieden L, Dadashev A, Vig S, Yehuda D, et al. Long-Term Outcomes and Characteristics Associated With Mortality of Adult Patients Post Fontan Surgery: 27-Year Single-Center Experience. Am J Cardiol. 2023;207:392-8.6. Poh CL, Cordina RL, Iyengar AJ, Zannino D, Grigg LE, Wheaton GR, et al. Pre- and Post-operative determinants of transplantation-free survival after Fontan. The Australia and New Zealand experience. Int J Cardiol Heart Vasc. 2021;35:100825.7. Rosner A, McElhinney DB, Diab SG, Friedberg MK, Lui GK. Classic-Pattern Dyssynchrony Is Associated with Outcome in Patients with Fontan Circulation. J Am Soc Echocardiogr. 2022;35(5):513-22.8. Aly S, Mertens L, Friedberg MK, Dragulescu A. Longitudinal Changes in Ventricular Mechanics in Adolescents After the Fontan Operation. J Am Soc Echocardiogr. 2023;36(9):998-1007.9. Chen TB, Sathananthan G, Janzen M, Grewal J. Two-Dimensional Strain Echocardiographic Parameters and Clinical Outcomes Associated with Significant Atrioventricular Regurgitation in a Single-Center Adult Fontan Population. J Cardiovasc Echogr. 2022;32(4):193-9.10. Ishizaki U, Nagao M, Shiina Y, Inai K, Mori H, Takahashi T, et al. Global strain and dyssynchrony of the single ventricle predict adverse cardiac events after the Fontan procedure: Analysis using feature-tracking cine magnetic resonance imaging. J Cardiol. 2019;73(2):163-70.11. Sethasathien S, Silvilairat S, Kraikruan H, Sittiwangkul R, Makonkawkeyoon K, Pongprot Y, et al. Survival and predictors of mortality in patients after the Fontan operation. Asian Cardiovasc Thorac Ann. 2020;28(9):572-6.12. Rosner A, Khalapyan T, Dalen H, McElhinney DB, Friedberg MK, Lui GK. Classic-Pattern Dyssynchrony in Adolescents and Adults With a Fontan Circulation. J Am Soc Echocardiogr. 2017.13. Schafer M, Mitchell MB, Frank BS, Barker AJ, Stone ML, Jaggers J, et al. Myocardial strain-curve deformation patterns after Fontan operation. Sci Rep. 2023;13(1):11912.14. Meyer SL, Ridderbos FS, Wolff D, Eshuis G, van Melle JP, Ebels T, et al. Serial cardiovascular magnetic resonance feature tracking indicates early worsening of cardiac function in Fontan patients. Int J Cardiol. 2020;303:23-9.15. Gearhart A, Bassi S, Rathod RH, Beroukhim RS, Lipsitz S, Gold MP, et al. Ventricular dyssynchrony late after the Fontan operation is associated with decreased survival. Journal of Cardiovascular Magnetic Resonance. 2023;25,66.16. Ghelani SJ, Colan SD, Azcue N, Keenan EM, Harrild DM, Powell AJ, et al. Impact of Ventricular Morphology on Fiber Stress and Strain in Fontan Patients. Circ Cardiovasc Imaging. 2018;11(7):e006738.17. Ghelani SJ, Harrild DM, Gauvreau K, Geva T, Rathod RH. Comparison Between Echocardiography and Cardiac Magnetic Resonance Imaging in Predicting Transplant-Free Survival After the Fontan Operation. Am J Cardiol. 2015;116(7):1132-8.18. Ghelani SJ, Lu M, Sleeper LA, Prakash A, Castellanos DA, Clair NS, et al. Longitudinal changes in ventricular size and function are associated with death and transplantation late after the Fontan operation. J Cardiovasc Magn Reson. 2022;24(1):56.19. Kramer P, Schleiger A, Schafstedde M, Danne F, Nordmeyer J, Berger F, et al. A Multimodal Score Accurately Classifies Fontan Failure and Late Mortality in Adult Fontan Patients. Front Cardiovasc Med. 2022;9:767503.20. Pundi KN, Johnson JN, Dearani JA, Pundi KN, Li Z, Hinck CA, et al. 40-Year Follow-Up After the Fontan Operation: Long-Term Outcomes of 1,052 Patients. J Am Coll Cardiol. 2015;66(15):1700-10.21. Inai K, Inuzuka R, Ono H, Nii M, Ohtsuki S, Kurita Y, et al. Predictors of long-term mortality among perioperative survivors of Fontan operation. Eur Heart J. 2022;43(25):2373-84.22. Khairy P, Fernandes SM, Mayer JE, Jr., Triedman JK, Walsh EP, Lock JE, et al. Long-term survival, modes of death, and predictors of mortality in patients with Fontan surgery. Circulation. 2008;117(1):85-92.23. Alsaied T, Bokma JP, Engel ME, Kuijpers JM, Hanke SP, Zuhlke L, et al. Factors associated with long-term mortality after Fontan procedures: a systematic review. Heart. 2017;103(2):104-10.24. Rao PS. Single Ventricle-A Comprehensive Review. Children (Basel). 2021;8(6).25. Kverneland LS, Kramer P, Ovroutski S. Five decades of the Fontan operation: A systematic review of international reports on outcomes after univentricular palliation. Congenit Heart Dis. 2018;13(2):181-93.26. Rosner A, Khalapyan T, Pedrosa J, Dalen H, McElhinney DB, Friedberg MK, et al. Ventricular mechanics in adolescent and adult patients with a Fontan circulation: Relation to geometry and wall stress. Echocardiography. 2018.27. Ohuchi H, Yasuda K, Miyazaki A, Kitano M, Sakaguchi H, Yazaki S, et al. Haemodynamic characteristics before and after the onset of protein losing enteropathy in patients after the Fontan operation. Eur J Cardiothorac Surg. 2013;43(3):e49-57.28. Atz AM, Zak V, Mahony L, Uzark K, Shrader P, Gallagher D, et al. Survival data and predictors of functional outcome an average of 15 years after the Fontan procedure: the pediatric heart network Fontan cohort. Congenit Heart Dis. 2015;10(1):E30-42.29. Kotani Y, Kasahara S, Fujii Y, Yoshizumi K, Oshima Y, Otsuki S, et al. Clinical outcome of the Fontan operation in patients with impaired ventricular function. Eur J Cardiothorac Surg. 2009;36(4):683-7.30. Potter E, Marwick TH. Assessment of Left Ventricular Function by Echocardiography: The Case for Routinely Adding Global Longitudinal Strain to Ejection Fraction. JACC Cardiovasc Imaging. 2018;11(2 Pt 1):260-74.31. Stylidis M, Leon DA, Rӧsner A, Schirmer H. Global myocardial longitudinal strain in a general population-associations with blood pressure and subclinical heart failure: The Tromso Study. Int J Cardiovasc Imaging. 2020;36(3):459-70. Transplant-free Survival N % mean ±SD (n=93) Death or Transplant N% mean ±SD (n=42) p -value Mean ±SD or n (%) Male 53 (65.4) 28 (34.6) 0.288 Female 40 (74.1) 14 (25.9) Age at Fontan (years) 5.7±5.7 4.0±4.3 0.132 Age at echocardiography (years) 21.6±9.9 17.3±8.7 0.033 Protein Losing Enteropathy 17 (56.7) 13 (43.3) 0.080 Classic Pattern Dyssynchrony 8 (53.3) 7 (46.7) 0.041 BP sys (mmHg) 112±14 83±18 0.008 BMI (kg/m 2 ) 21.7±8.8 21.5±7.2 0.930 Anatomy 0.032 BV 14(53.8) 12 (46.2) LV 43 (76.8) 13 (23.2) RV 27 (64.3) 15 (35.7) SV 9 (81.8) 2 (18.2) Long/Trans Diameter Ratio () Aortic Valve Regurgitation grade I 82 (71.3) 33 (28.7) 0.540 Aortic Valve Regurgitation grade II 11 (64.7) 6 (35.3) Aortic Valve Regurgitation grade III-IV 0 (0) 3 (100) Type Fontan 0.481 RA to PA 10 (66.7) 5 (33.3) Lateral tunnel 28 (75.7) 9 (24.3) Extracardiac 35 (60.3) 23 (39.7) Unknown 20 (80.0) 5 (20.0) NYHA 0.003 Class I 18 (78.3) 5 (21.7) Class II 50 (73.5) 18 (26.5) Class III 14 (48.3) 15 (51.7) Class IV 1 (33.3) 2 (66.7) HR (bpm) 78±15 83±18 0.129 Systole/Diastole Ratio () 0.97±0.31 1.09±0.30 0.060 EF (%) 46±14 35±15 <0.001 Long Strain sys (%) -16.7±6.9 -9.8±6.8 <0.001 EF: ejection fraction; BV: two sizable ventriclular components, mostly patients with unbalanced atrioventricular canal; LV: left ventricular; RV right ventricular; SV: single ventricle; RA to PA: right atrium to pulmonary artery; BP: blood pressure; BMI: body mass index; BSA: body surface area; HR: heart rate; Long: longitudinal; Circ: circumferential; SR E DT: E wave deceleration time; AV valve: atrioventricular valve Table 2: ANOVA for ventricular functional parameters for systole and diastole All CPD Transplant free survival CPD Transplantation/Death PLE Transplant free survival PLE Transplantation/Death Others Transplant free survival Others Transplantation/Death n 132 8 7 16 13 68 20 Mean SD Mean SD Mean SD Mean SD Mean SD Mean SD Mean SD BP sys (mmHg) 110.2 ±14.6 111 ±13 110 ±12 108 ±14 98 ±14 114 ±15 106 ±14 BP dia (mmHg) 65.6 ±11.4 67 ±11 70 ±10 61 ±8 53* † ±9 68 ±11 65 ±11 HR (/min) 79.9 ±16.0 76.0 ±18.3 89.9* ±13.0 88 ±15 83 ±21 77 ±15 80 ±15 Volume ED (ml) 140 ±79 101 ±35 229* ±146 123 ±78 132 ±66 131 ±57 169 ±111 Volum ES (ml) 83.8 ±62.1 63 ±31 180* † ±47 71 ±52 83 ±55 72 ±40 111 ±84 GLS sys (%) -14.2 ±7.4 -13.1 ±5.8 -6.1* 3.3 -16.5 ±6.6 -12.5 ±7.3 -16.3 ±7.4 -10.6* ±5.6 GLSR S (1/s) -0.87 ±0.43 -0.73 ±0.51 -0.51 ±0.36 -1.14 ±0.48 -0.88 ±0.40 -0.95 ±0.4 -0.63* ±0.33 GLSR E (1/s) 1.08 ±0.74 0.79 ±0.38 0.53 ±0.32 1.34 ±0.79 1.08 ±0.52 1.17 ±0.81 0.91 ±0.61 GCS sys (%) -14.5 ±7.3 -12.3 4.5 -6.0* ±3.7 -16.2 ±6.7 -14.4 ±7.5 -16.3 ±7.3 -10.4* ±5.8 GCSR S (1/s) -0.88 ±0.42 -0.74 ±0.25 -0.39* ±0.23 -1.09 ±0.44 -0.90 ±0.40 0.96 ±0.41 -0.63* ±0.34 GCSR E (1/s) 1.09 ±0.73 0.75 ±0.28 0.54 ±0.35 1.30 ±0.21 1.09 ±0.54 1.18 ±0.81 0.91 ±0.61 EF (%) 42.8 ±14.7 38.5 ±15.2 23.5* † 10.4 44.7 ±12.3 39.3 ±14.9 46.6 ±13.0 37.7* ±16.5 Systole/diastole 0.92 ±0.28 1.16 ±0.33 1.09 0.31 1.10 ±0.29 0.91 ±0.26 1.12* ±0.33 AVV E Wave (cm/s) 72 ±25 63 ±15 67 ±19 91 29 88 ±27 68 ±21 68 ±27 AVV E/A ratio 1.30 ±0.57 1.03 ±0.52 1.19 0.56 1.70 0.75 1.47 ±0.61 1.19 ±0.41 1.48* ±0.82 AVV E DT (ms) 155 ±57 197 ±106 127 ±24 162 ±56 144 ±57 160 ±51 124 ±45 SR E/e´ 109 ±51 167 ±149 92 ±48 120 ±58 92 ±48 120 ±58 * p <0.05 for comparison towards “transplant-free survival”; † p <0.05 for comparison towards “All” Data on patients with strain-rate analyses. BP: blood pressure; HR: heart rate; ED: end-diastolic; ES: end-systolic; GLS: global longitudinal strain; GCS: global circumferential strain; GLSR: global longitudinal strain rate; GCSR. Global circumferential strain rate; sys/S: systole; E: early filling; dia: diastole; GCS: global circumferential strain; EF: ejection fraction: AVV: atrio ventricular valve; SR E/e’: E/strain-rate derived e’ Tx-free Survival Tx Death Tx + Death Total n (%) n (%) n (%) n (%) n GLS <-16% 31 (94) 1 (3) 1 (3) 0 (0) 33 GLS <-8% ≥-16% 27 (73) 4 (11) 5 (14) 1(3) 37 GLS ≥-8% 10 (56) 5 (28) 1 (6) 2 (11) 18 CPD 8 (53) 4 (27) 0 (0) 3 (20) 15 PLE 16 (55) 11 (38) 1 (3) 1 (3) 29 GLS: peak systolic global longitudinal strain; CPD: classic pattern dyssynchrony; PLE: protein losing enteropathy. Univariable Cox regression analysis Multivariable Cox regression analysis p -value HR CI lower bound CI upper bound P value HR CI lower bound CI upper bound *Protein Losing Enteropathy 0.008 2.45 1.26 4.74 0.032 2.25 1.08 4.73 *Classic Pattern Dyssynchrony 0.012 3.05 1.28 7.23 0.72 1.89 0.944 3.78 *EF (%) <0.001 0.96 0.94 0.98 n.s. *Anatomy 0.001 n.s. BV 0.002 2.78 1.46 5.28 LV n.s. RV n.s. SV n.s. *Long/Trans Diameter Ratio () <0.001 0.117 0.033 0.414 n.s. *NYHA 0.007 n.s. Class I Class II n.s. Class III n.s. Class IV 0.027 6.50 1.23 34.28 *BP sys (mmHg) 0.001 0.96 0.94 0.98 0.005 0.960 0.94 0.97 *BP dia (mmHg) 0.001 0.94 0.91 0.98 n.s. *HR (bpm) 0.010 1.027 1.01 1.05 n.s. *Systolic/Diastolic Duration Ratio () <0.001 4.42 1.91 10.20 n.s. *Long Strain sys (%) <0.001 1.13 1.07 1.18 <0.001 1,20 1.11 1.30 *Long SR sys (s -1 ) <0.001 2.36 2.36 12.70 n.s. *Long SR E (s -1 ) 0.011 0.526 0.304 0.910 0.033 2.19 1.07 4.51 *Circ Strain sys (%) <0.001 1.10 1.05 1.16 n.s. *Circ SR sys (s -1 ) <0.001 5.54 2.24 13.74 n.s. *Circ SR E (s -1 ) 0.042 0.56 0.32 0.98 n.s. Peak E velocity (cm/s) n.s. *E DT (ms) <0.001 0.99 0.980 0.996 n.s. E/A ratio () n.s. *E/e´sept () <0.001 0.997 0.995 0.999 n.s. E/e´lat () n.s. Aortic valve regurgitation n.s. Atrio ventricular valve regurgitation n.s. Cox regression for groups Multivariable Cox regression analysis GLS <-16% 0.004 GLS <-8% ≥-16% 0.023 5.80 1.27 26.5 GLS ≥-8% 0.003 10.3 2.18 48.6 CPD 0.002 11.5 2.39 55.6 PLE <0.001 14.9 3.32 66.4 *parameters entered into the forward multiple regression analysis EF: ejection fraction; BV: two sizable ventriclular components, mostly patients with unbalanced atrioventricular canal; LV: left ventricular; RV right ventricular; SV: single ventricle; RA to PA: right atrium to pulmonary artery; BP: blood pressure; BMI: body mass index; VO2: ; HR: heart rate; Long: longitudinal; Circ: circumferential; SR: strain rate; E DT: E wave deceleration time; AV valve: atrioventricular valve p-value HR 95% CI Lower 95% CI Upper GLS <-16% 0.16 GLS <-8% ≥-16% 0.055 4.41 0.97 20.14 GLS ≥-8% 0.006 8.64 1.83 40.72 CPD 0.004 9.92 2.06 47.79 PLE 0.003 9.57 2.16 42.51 Figure 1: Survival Function for Fontan circulation patients, comparing those with protein-losing enteropathy (PLE), classic pattern dyssynchrony (CPD), and those with low and moderately reduced Global Longitudinal Strain (GLS), against patients without these risk factors. Figure 2: Survival Function for Fontan circulation patients with date of echocardiography as reference point, illustrating the survival patterns of those with protein-losing enteropathy (PLE), classic pattern dyssynchrony (CPD), and low Global Longitudinal Strain (GLS), contrasted with patients free from these three risk factors. Figure 3: Comprehensive overview of Death/Transplantation (Tx) in Fontan circulation patients, depicting the distribution of survivors and patients who died or underwent transplantation across different ages and risk factors. The visualization includes protein-losing enteropathy (PLE), classic pattern dyssynchrony (CPD), and “Other Fontan” without CPD or PLE at different Global Longitudinal Strain (GLS) levels, with survivors represented by circles and patients who died or were transplanted marked as triangles. Information & Authors Information Version history V1 Version 1 18 June 2025 Peer review timeline Published Echocardiography Version of Record 18 Sep 2025 Published Copyright This work is licensed under a Non Exclusive No Reuse License. Collection Echocardiography Keywords fontan operation heart-failure strain rate imaging transplantfree survival univentricular hearts Authors Affiliations Assami Rosner 0000-0001-9084-5805 [email protected] Universitetssykehuset Nord-Norge HF View all articles by this author Simone Goa Diab Oslo universitetssykehus Barnekardiologisk avdeling View all articles by this author Mark Friedberg The Hospital for Sick Children View all articles by this author George Lui Stanford University Division of Cardiovascular Medicine View all articles by this author Metrics & Citations Metrics Article Usage 222 views 215 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Assami Rosner, Simone Goa Diab, Mark Friedberg, et al. 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