Outcome after extracorporeal membrane oxygenation therapy in Norwood patients before the bidirectional Glenn operation.

OBJECTIVES: Patients after the Norwood procedure are prone to postoperative instability. Extracorporeal membrane oxygenation (ECMO) can help to overcome short-term organ failure. This retrospective single-centre study examines ECMO weaning, hospital discharge and long-term survival after ECMO therapy between Norwood and bidirectional Glenn palliation as well as risk factors for mortality. METHODS: In our institution, over 450 Norwood procedures have been performed. Since the introduction of ECMO therapy, 306 Norwood operations took place between 2007 and 2022, involving ECMO in 59 cases before bidirectional Glenn. In 48.3% of cases, ECMO was initiated intraoperatively post-Norwood. Patient outcomes were tracked and mortality risk factors were analysed using uni- and multivariable testing. RESULTS: ECMO therapy after Norwood (median duration: 5 days; range 0-17 days) saw 31.0% installed under CPR. Weaning was achieved in 46 children (78.0%), with 55.9% discharged home after a median of 45 (36-66) days. Late death occurred in 3 patients after 27, 234 and 1541 days. Currently, 30 children are in a median 4.8 year (3.4-7.7) follow-up. At the time of inquiry, 1 patient awaits bidirectional Glenn, 6 are at stage II palliation, Fontan was completed in 22 and 1 was lost to follow-up post-Norwood. Risk factor analysis revealed dialysis (P < 0.001), cerebral lesions (P = 0.026), longer ECMO duration (P = 0.002), cardiac indication and lower body weight (P = 0.038) as mortality-increasing factors. The 10-year mortality probability after ECMO therapy was 48.5% (95% CI 36.5-62.9%). CONCLUSIONS: ECMO therapy in critically ill patients after the Norwood operation may significantly improve survival of a patient cohort otherwise forfeited and give the opportunity for successful future-stage operations.

Textbook Outcome for Superior Cavopulmonary Connection: A Metric for Single Ventricle Heart Surgery.

Background: To develop a more holistic measure of congenital heart center performance beyond mortality, we created a composite "textbook outcome" (TO) for the Glenn operation. We hypothesized that meeting TO would have a positive prognostic and financial impact. Methods: This was a single center retrospective study of patients undergoing superior cavopulmonary connection (bidirectional Glenn or Kawashima ± concomitant procedures) from 2005 to 2021. Textbook outcome was defined as freedom from operative mortality, reintervention, 30-day readmission, extracorporeal membrane oxygenation, major thrombotic complication, length of stay (LOS) >75th percentile (17d), and mechanical ventilation duration >75th percentile (2d). Multivariable logistic regression and Cox proportional hazards modeling were used. Results: Fifty-one percent (137/269) of patients met TO. Common reasons for TO failure were prolonged LOS (78/132, 59%) and ventilator duration (67/132, 51%). In multivariable analysis, higher weight [odds ratio, OR: 1.44 (95% confidence interval, CI: 1.15-1.84), P = .002] was a positive predictor of TO achievement while right ventricular dominance [OR 0.47 (0.27-0.81), P = .007] and higher preoperative pulmonary vascular resistance [OR 0.58 (0.40-0.82), P = .003] were negative predictors. After controlling for preoperative factors and excluding operative mortalities, TO achievement was independently associated with a decreased risk of death over long-term follow-up [hazard ratio: 0.50 (0.25-0.99), P = .049]. Textbook outcome achievement was also associated with lower direct cost of care [$137,626 (59,333-167,523) vs $262,299 (114,200-358,844), P < .0001]. Conclusion: Achievement of the Glenn TO is associated with long-term survival and lower costs and can be predicted by certain risk factors. As outcomes continue to improve within congenital heart surgery, operative mortality will become a less informative metric. Textbook outcome analysis may represent a more balanced measure of a successful outcome.

Pacemaker-Related Factors and Outcomes of Fontan Patients　- Impact of Paced QRS Duration.

BACKGROUND: Permanent pacemaker (PPM) implantation has been identified as a risk factor for morbidity and mortality after Fontan operation. This study investigated the factors associated with outcomes in patients with Fontan physiology who underwent PPM implantation.Methods and Results: We retrospectively reviewed 508 patients who underwent Fontan surgery at Asan Medical Center between September 1992 and August 2022. Of these patients, 37 (7.3%) received PPM implantation. Five patients were excluded, leaving 32 patients, of whom 11 were categorized into the poor outcome group. Poor outcomes comprised death, heart transplantation, and "Fontan failure". Clinical, Fontan procedure-related, and PPM-related factors were compared between the poor and good outcome groups. Ventricular morphology, Fontan procedure-associated factors, pacing mode, high ventricular pacing rate, and time from first arrhythmia to PPM implantation did not differ significantly between the 2 groups. However, the poor outcome group exhibited a significantly longer mean paced QRS duration (P=0.044). Receiver operating characteristic curve analysis revealed a paced QRS duration cut-off value of 153 ms with an area under the curve of 0.73 (P=0.035). CONCLUSIONS: A longer paced QRS duration was associated with poor outcomes, indicating its potential to predict adverse outcomes among Fontan patients.

Biventricular conversion after Fontan completion: A preliminary experience.

OBJECTIVE: To assess the feasibility and outcomes of biventricular conversion following takedown of Fontan circulation. METHODS: Retrospective analysis of patients who had takedown of Fontan circulation and conversion to biventricular circulation at a single center from September 2007 to April 2020. Failing Fontan physiology was defined as Fontan circulation pressure >15 mm Hg and/or the presence of associated complications. RESULTS: Biventricular conversion was performed in 23 patients at a median age of 10.0 (7.5-13.0) years. Indications included failing Fontan physiology in 15 (65%) and elective takedown in 8 (35%) patients. A subset of patients (n = 6) underwent procedures for staged recruitment of the nondominant ventricle before conversion. Median z score of end-diastolic volume of borderline ventricle before takedown was -2.3 (-3.3, -1.3). Hypoplastic left heart syndrome (P < .01) and sub-/aortic stenosis (P < .01) were more common in these patients. Biventricular conversion with or without staged ventricular recruitment led to a significant increase in indexed end-diastolic volume (P < .01), indexed end-systolic volume (P < .01), and ventricular mass (P < .01) of the nondominant ventricle (14 right, 9 left ventricle). There were 5 (22%) deaths (1 [4%] early death). All who underwent elective biventricular conversion survived, whereas 2-year survival rate for patients with a failing Fontan circulation was 72.7% (95% confidence interval, 37%-90%). The overall, 3-year reoperation-free survival was 86.7% (95% confidence interval, 56%-96%). Left dominant atrioventricular canal defect (P < .01) and early era of biventricular conversion (P = .02) were significant predictors for mortality. CONCLUSIONS: A primary as well as a staged biventricular conversion is feasible in patients who have had previous Fontan procedure. Although this provides an alternative to transplantation in patients with failing Fontan, outcomes are worse in those with failing Fontan compared with elective takedown of Fontan circulation. Optimal timing needs further evaluation.

Factors associated with mortality or transplantation versus Fontan completion after cavopulmonary shunt for patients with tricuspid atresia.

OBJECTIVE: Tricuspid atresia with normally related great vessels (TA) is considered the optimal substrate for the Fontan pathway. The factors associated with death or transplantation after cavopulmonary shunt (CPS) are underappreciated. We aimed to determine factors associated with CPS-Fontan interstage death/transplantation versus transition to Fontan in TA. METHODS: A total of 417 infants younger than 3 months of age with TA were enrolled (January 1999 to February 2020) from 40 institutions into the Congenital Heart Surgeons' Society TA cohort. Parametric competing risk methodology was used to determine factors associated with the competing end points of death/transplantation without Fontan completion, and transition to Fontan. RESULTS: CPS was performed in 382 patients with TA; of those, 5% died or underwent transplantation without transition to Fontan and 91% transitioned to Fontan by 5 years after CPS. Prenatal diagnosis (hazard ratio [HR], 0.74; P < .001) and pulmonary artery band (PAB) at CPS (HR, 0.50; P < .001) were negatively associated with Fontan completion. Preoperative moderate or greater mitral valve regurgitation (HR, 3.0; P < .001), concomitant mitral valve repair (HR, 11.0; P < .001), PAB at CPS (HR, 3.0; P < .001), postoperative superior vena cava interventions (HR, 9.0; P < .001), and CPS takedown (HR, 40.0; P < .001) were associated with death/transplantation. CONCLUSIONS: The mortality rate after CPS in patients with TA is notable. Those with preoperative mitral valve regurgitation remain a high-risk group. PAB at the time of CPS being associated with both increased risk of death and decreased Fontan completion may represent a deleterious effect of antegrade pulmonary blood flow in the CPS circulation.

Integrated Clinical and Magnetic Resonance Imaging Assessments Late After Fontan Operation.

BACKGROUND: Several clinical and cardiac magnetic resonance (CMR)-derived parameters have been shown to be associated with death or heart transplant late after the Fontan operation. OBJECTIVES: The objective of this study was to identify the relative importance and interactions of clinical and CMR-based parameters for risk stratification after the Fontan operation. METHODS: Fontan patients were retrospectively reviewed. Clinical and CMR parameters were analyzed using univariable Cox regression. The primary endpoint was time to death or (listing for) heart transplant. To identify the patients at highest risk for the endpoint, classification and regression tree survival analysis was performed, including all significant variables from Cox regression. RESULTS: The cohort consisted of 416 patients (62% male) with a median age of 16 years (25th, 75th percentiles: 11, 23 years). Over a median follow-up of 5.4 years (25th, 75th percentiles: 2.4, 10.0 years) after CMR, 57 patients (14%) reached the endpoint (46 deaths, 7 heart transplants, 4 heart transplant listings). Lower total indexed end-diastolic volume (EDVi) was the strongest predictor of transplant-free survival. Among patients with dilated ventricles (EDVi ≥156 ml/BSA1.3), worse global circumferential strain (GCS) was the next most important predictor (73% vs. 44%). In patients with smaller ventricles (EDVi <156 ml/BSA1.3), New York Heart Association functional class ≥II was the next most important predictor (30% vs. 4%). CONCLUSIONS: In this cohort of patients late after Fontan operation, increased ventricular dilation was the strongest independent predictor of death or transplant (listing). Patients with both ventricular dilation and worse GCS were at highest risk. These data highlight the value of integrating CMR and clinical parameters for risk stratification in this population.

Attrition between the superior cavopulmonary connection and the Fontan procedure in hypoplastic left heart syndrome.

OBJECTIVE: We investigated the incidence and predictors of failure to undergo the Fontan in children with hypoplastic left heart syndrome who survived superior cavopulmonary connection. METHODS: The cohort consists of all patients with hypoplastic left heart syndrome who survived to hospital discharge after superior cavopulmonary connection between 1988 and 2017. The primary outcome was attrition, which was defined as death, nonsuitability for the Fontan, or cardiac transplantation before the Fontan. Subjects were excluded if they were awaiting the Fontan, were lost to follow-up, or underwent biventricular repair. The study period was divided into 4 eras based on changes in operative or medical management. Attrition was estimated with 95% confidence intervals, and predictors were identified using adjusted, logistic regression models. RESULTS: Of the 856 hospital survivors after superior cavopulmonary connection, 52 died, 7 were deemed unsuitable for Fontan, and 12 underwent or were awaiting heart transplant. Overall attrition was 8.3% (71/856). Attrition rate did not change significantly across eras. A best-fitting multiple logistic regression model was used, adjusting for superior cavopulmonary connection year and other influential covariates: right ventricle to pulmonary artery shunt at Norwood (P < .01), total support time at superior cavopulmonary connection (P < .01), atrioventricular valve reconstruction at superior cavopulmonary connection (P = .02), performance of other procedures at superior cavopulmonary connection (P = .01), and length of stay after superior cavopulmonary connection (P < .01). CONCLUSIONS: In this study spanning more than 3 decades, 8.3% of children with hypoplastic left heart syndrome failed to undergo the Fontan after superior cavopulmonary connection. This attrition rate has not decreased over 30 years. Use of a right ventricle to pulmonary artery shunt at the Norwood procedure was associated with increased attrition.

Protein-losing enteropathy and plastic bronchitis after the Fontan procedure.

OBJECTIVES: Protein losing enteropathy and plastic bronchitis are severe complications in Fontan circulation, with 5-year survival ranging from 46% to 88%. We report risk factors and outcomes of protein losing enteropathy and plastic bronchitis in patients undergoing the Fontan. METHODS: We performed a retrospective analysis of 1561 patients from the Australia New Zealand Fontan Registry. Two end points were death and cardiac transplantation examined with Cox regression (if no competing risks) or cumulative incidence curves and cause-specific Cs regression. RESULTS: A total of 55 patients with protein losing enteropathy/plastic bronchitis were included. Their median age at the Fontan was 5.7 years, and time to onset after the Fontan for protein losing enteropathy was 5.0 years and plastic bronchitis was 1.7 years. Independent predictors for developing protein losing enteropathy/plastic bronchitis were right-ventricular morphology with hypoplastic left-heart syndrome (hazard ratio, 2.30; confidence interval, 1.12-4.74), older age at Fontan (hazard ratio, 1.13; confidence interval, 1.03-1.23), and pleural effusions after Fontan (hazard ratio, 2.43; confidence interval, 1.09-5.41); left-ventricular morphology was protective (hazard ratio, 0.36; confidence interval, 0.18-0.70). In the protein losing enteropathy/plastic bronchitis population, freedom from death or transplantation after protein losing enteropathy/plastic bronchitis diagnosis at 5, 10, and 15 years was 70% (confidence interval, 58-85), 65% (confidence interval, 51-83), and 43% (confidence interval, 26-73), respectively; only older age (hazard ratio, 1.23; confidence interval, 1.01-1.52) was an independent predictor. Twenty-six surgical interventions were performed in 20 patients, comprising Fontan revisions (n = 5), fenestrations (n = 11), Fontan conversions (n = 5), atrioventricular valve repairs (n = 3), and hepatic vein diversion (n = 2). CONCLUSIONS: Protein losing enteropathy and plastic bronchitis remain severe complications, preferably affecting patients with dominant right single ventricle, with older age at Fontan being a predictor of developing protein losing enteropathy/plastic bronchitis and poorer prognosis. Heart transplantation remains the ultimate treatment, with 30% dying or requiring transplantation within 5 years, and the remaining being stable for long periods.

Long-term outcomes following Fontan takedown in Australia and New Zealand.

OBJECTIVE: Fontan takedown remains an option for the management of Fontan failure. We sought to evaluate early and late outcomes after Fontan takedown. METHODS: The Australia and New Zealand Fontan Registry was interrogated to identify all patients who had a Fontan takedown. RESULTS: Over a 43-year study period (1975-2018), 36 of 1540 (2.3%) had a Fontan takedown. The median age at takedown was 5.1 years (interquartile range [IQR], 3.7, 7.0). Nine (25%) patients had a takedown within 48 hours, 6 (16%) between 2 days and 3 weeks, 14 (39%) between 3 weeks and 6 months, whereas 7 (19%) had a late takedown (>6 months). Median interval to takedown was 26 days (IQR, 1.5, 127.5). Sixteen (44%) patients died at a median of 57.5 days (IQR, 21.8, 76.8). The greatest mortality occurred between 3 weeks and 6 months (<2 days: 1/9, 11%; 2 days to 3 weeks: 2/6, 33%; 3 weeks to 6 months: 11/14, 79%; >6 months: 2/7, 28%; P = .007). At median follow-up of 9.4 years (IQR, 4.5, 15.3), 11 (31%) patients were alive with an intermediate circulation (10 in New York Heart Association class I/II). Five (14%) patients underwent a successful second Fontan. Freedom from death/transplant after Fontan takedown was 59%, 56%, and 52% at 1, 5, and 10 years, respectively. CONCLUSIONS: The incidence of Fontan takedown is low, but mortality is high. The majority of takedowns occurred within 6 months. Mortality was lowest when takedown occurred <2 days and highest between 3 weeks and 6 months. A second Fontan is possible in a small proportion of survivors.

The Adult Patient with a Fontan.

The authors summarize the most important anatomic and physiologic substrates of Fontan circulation. Common anatomic substrates include hypoplastic left heart syndrome, tricuspid atresia, double inlet left ventricle, and unbalanced atrioventricular septal defects. After the Fontan operation exercise capacity is limited and the key hemodynamic drivers is limited preload due to a relatively fixed pulmonary vascular resistance. The authors provide contemporary data on survival, morbidity, and need for reintervention. Operative morality is now expected to be less than 1% and 30 year survival approximately 89%. The authors delineate potential therapeutic approaches for the potential late complications.

Tricuspid atresia: Where are we now?

Tricuspid atresia (TA) is a complex congenital heart disease that presents with cyanosis in the neonatal period. It is invariably fatal if left untreated and requires multiple stages of palliation. Early recognition and timely surgical intervention are therefore pivotal in the management of these infants. This literature review considers the pathophysiology, presentation, investigations, and classification of TA. Moreover, it discusses the evidence upon which the latest medical and surgical treatments are based, as well as numerous recent case reports. Further work is needed to elucidate the etiology of TA, clarify the role of pharmacotherapy, and optimize the surgical management that these patients receive.

Atrioventricular Valve Regurgitation in Single Ventricle Heart Disease: A Common Problem Associated With Progressive Deterioration and Mortality.

The Fontan procedure has provided patients with single ventricle physiology extended survival into adulthood and in many cases has improved their quality of life. Atrioventricular valve regurgitation (AVVR) is common in single ventricle patients and is associated with increased risk of mortality. AVVR is more common in patients with a systemic tricuspid or common atrioventricular valve but is generally progressive irrespective of underlying valve morphology. AVVR can be attributable to diverse structural and functional abnormalities at multiple levels of the valvar apparatus, as well as ventricular dysfunction and dilation. Multiple imaging modalities including recent advances in 3-dimensional echocardiography and cross-sectional imaging have been used to further understand AVVR. Surgery to address AVVR must be tailored to the underlying mechanism and the timing of surgical repair should be chosen carefully. In this review, we discuss the etiologies, treatment options, surgical timing, and outcomes of valve repair or replacement for AVVR in patients with single ventricle congenital heart disease, with a focus on those with a Fontan circulation as AVVR is associated with increased risk for Fontan failure and mortality. In-depth understanding of the current literature will help guide clinicians in their approach and management of AVVR in this population.

Prevalence and Cause of Early Fontan Complications: Does the Lymphatic Circulation Play a Role?

Background Recent studies suggest that lymphatic congestion plays a role in development of late Fontan complications, such as protein-losing enteropathy. However, the role of the lymphatic circulation in early post-Fontan outcomes is not well defined. Methods and Results This was a retrospective, single-center study of patients undergoing first-time Fontan completion from 2012 to 2017. The primary outcome was early Fontan complication ≤6 months after surgery, a composite of death, Fontan takedown, extracorporeal membrane oxygenation, chest tube drainage >14 days, cardiac catheterization, readmission, or transplant. Complication causes were assigned to 1 of 4 groups: (1) Fontan circuit obstruction, (2) ventricular dysfunction or atrioventricular valve regurgitation, (3) persistent pleural effusions in the absence of Fontan obstruction or ventricular dysfunction, and (4) chylothorax or plastic bronchitis. T2-weighted magnetic resonance imaging sequences were used to assess for lymphatic perfusion abnormality. The cohort consisted of 238 patients. Fifty-eight (24%) developed early complications: 20 of 58 (34.5%) in group 1, 8 of 58 (14%) in group 2, 18 of 58 (31%) in group 3, and 12 of 58 (20%) in group 4. Preoperative T2 imaging was available for 126 (53%) patients. Patients with high-grade lymphatic abnormalities had 6 times greater odds of developing early complications (P=0.001). Conclusions There is substantial morbidity in the early post-Fontan period. Half of those who developed early complications had lymphatic failure or persistent effusions unrelated to structural or functional abnormalities. Preoperative T2 imaging demonstrated that patients with higher-grade lymphatic perfusion abnormalities were significantly more likely to develop early complications. This has implications for risk stratification and optimization of patients before Fontan palliation.

Effectiveness of Bidirectional Glenn Shunt Placement for Palliation in Complex Congenitally Corrected Transposed Great Arteries.

Surgery for complex congenitally corrected transposed great arteries is one of the greatest challenges in cardiovascular surgery. We report our experience with bidirectional Glenn shunt placement as a palliative procedure for complex congenitally corrected transposition. We retrospectively identified 50 consecutive patients who had been diagnosed with congenitally corrected transposition accompanied by left ventricular outflow tract obstruction and ventricular septal defect and who had then undergone palliative bidirectional Glenn shunt placement at our institution from January 2005 through December 2014. Patients were divided into 3 groups according to subsequent surgeries: Fontan completion (total cavopulmonary connection, 13 patients) (group 1), anatomic repair (hemi-Mustard and Rastelli procedures without Glenn takedown, 11 patients) (group 2), and prolonged palliation (no further surgery, 26 patients) (group 3). After shunt placement, no patient died or had ventricular dysfunction. Overall, mean oxygen saturation increased significantly from 79.5% ± 13.5% preoperatively to 94.1% ± 7.3% (P <0.001). The median time from shunt placement to Fontan completion and anatomic repair, respectively, was 2.1 years (range, 1.6-5.2 yr) and 1.1 years (range, 0.6-2.4 yr). Only 2 late deaths occurred, both in group 1. In group 3, time from shunt placement to latest follow-up was 4.5 years (range, 2.3-8 yr). At latest follow-up, mean oxygen saturation was 91.6% ± 10.3%, and no patients had impaired ventricular function. Bidirectional Glenn shunt placement as an optional palliative procedure for complex congenitally corrected transposition has favorable outcomes. Later, patients can feasibly be treated by Fontan completion or anatomic repair. Use of a bidirectional Glenn shunt for open-ended palliation is also acceptable.

Identification of Risk Factors for Early Fontan Failure.

Despite improvements in operative and perioperative care, the risk of significant morbidity and mortality for children undergoing Fontan procedures persists. Previous investigations have identified peri-Fontan characteristics that may predict early adverse events. The purpose of this study was to identify characteristics from throughout a patient's lifespan, including all perioperative stages, that might predict early Fontan failure-defined as death, Fontan takedown, or listing for cardiac transplantation before hospital discharge or within 30 postoperative days. A single-center retrospective study of all patients undergoing a Fontan procedure was performed. Patient and intervention-related characteristics were examined from birth through Fontan. Data were described using standard summary statistics. Univariable, logistic regression was used to examine associations with early Fontan failure. In total, 191 patients met inclusion criteria. The incidence of early Fontan failure was 4% (n = 8: 6 deaths, 2 Fontan takedowns). Neonatal balloon atrial septostomy was the only patient characteristic significantly associated with Fontan failure. Patients who underwent balloon septostomy had 8.5 times higher odds of Fontan failure (confidence interval (CI) 2.6-28.1, P < 0.001) than those who did not. Children who require balloon septostomy as neonates remain at higher risk of Fontan takedown, listing for heart transplantation, or death in the early post-Fontan period.

Survival, Neurocognitive, and Functional Outcomes After Completion of Staged Surgical Palliation in a Cohort of Patients With Hypoplastic Left Heart Syndrome.

Background Management of patients with hypoplastic left heart syndrome has benefited from advancements in medical and surgical care. Outcomes have improved, although survival and long-term functional and cognitive deficits remain a concern. Methods and Results This is a cohort study of all consecutive patients with hypoplastic left heart syndrome undergoing surgical palliation at a single center. We aimed to examine demographic and perioperative factors from each surgical stage for their association with survival and neurocognitive outcomes. A total of 117 consecutive patients from 1996 to 2010 underwent surgical palliation. Seventy patients (60%) survived to the Fontan stage and 68 patients (58%) survived to undergo neurocognitive assessment at a mean (SD) age of 56.6 months (6.4 months). Full-scale, performance, and verbal intelligence quotient, as well as visual-motor integration mean (SD) scores were 86.7 (16.1), 86.3 (15.8), 88.8 (17.2), and 83.2 (14.8), respectively. On multivariable analysis, older age at Fontan, sepsis peri-Norwood, lowest arterial partial pressure of oxygen postbidirectional cavopulmonary anastomosis, and presence of neuromotor disability pre-Fontan were strongly associated with lower scores for all intelligence quotient domains. Older age at Fontan and sepsis peri-Norwood remained associated with lower scores for all intelligence quotient domains in a subgroup analysis excluding patients with disability pre-Fontan or with chromosomal abnormalities. Conclusions Older age at Fontan and sepsis are among independent predictors of poor neurocognitive outcomes for patients with hypoplastic left heart syndrome. Further studies are required to identify the appropriate age range for Fontan completion, balancing a lower risk of acute and long-term hemodynamic complications while optimizing long-term neurocognitive outcomes.

The Progress and Significance of QRS Duration by Electrocardiography in Hypoplastic Left Heart Syndrome.

Patients with hypoplastic left heart syndrome (HLHS) are now surviving through to Fontan palliation and beyond, however, with increased morbidity and mortality. Prolonged QRSd has become one of the predictors of morbidity and mortality in certain congenital heart diseases. There is limited data characterizing the QRSd in patients with HLHS. We aimed to describe the changes in QRSd at various times during the lifetime and to evaluate whether QRSd correlates with a higher risk of developing a composite endpoint of heart failure, heart transplant, or death. We conducted a retrospective chart review of patients with HLHS who survived Fontan palliation. QRSd was measured on ECGs at various stages pre- and postsurgical palliations and subsequently at 5 year intervals. Patients with a composite endpoint were compared to those without. A total of 89 patients were included in the final analysis. The QRSd increased significantly with time from 68.7 ± 9.0 ms prior to Norwood to 91.0 ± 14.0 ms immediately following Fontan and 104.7 ± 13.6 ms 15 years after Fontan (p < 0.001). The composite endpoint was observed in 28 patients (31.4%). The time trends of QRSd differ so that the patients having the composite endpoint experienced a greater increase in QRSd over time (p = 0.009). Ever having a QRSd of 120 ms or more predicted the composite endpoint with 93% specificity. The area under the curve of the receiver operator curve analysis was 0.596. A Cox regression analysis demonstrated that QRS duration > 120 ms was independently related to a greater frequency of composite endpoint and this was confirmed by a Kaplan-Meier analysis (p = 0.011). This study unveils a novel relationship between QRSd of 120 ms or more with the composite endpoint. Despite the low sensitivity, this finding on a routine surveillance ECG could help identify HLHS Fontan patients at risk for heart failure, heart transplant, or death.

Competing risks analysis of time-to-event data for cardiovascular surgeons.

OBJECTIVES: The purpose of this article is to provide thoracic and cardiovascular surgeons with a practical step-by-step strategy to use in collaboration with a biostatistician for implementation of competing risks analysis when analyzing time-to-event data. Patients may have an outside event that precludes the event of interest. Traditional time-to-event analysis incorrectly assumes noninformative censoring in this scenario, which will lead to invalid results and conclusions. METHODS: The steps are (1) to determine whether competing risks analysis is needed, (2) to perform a nonparametric analysis, (3) to perform a model-based analysis, (4) to interpret the results, and (5) to compare to traditional survival analysis methods. We apply our approach to a hypothetical cardiovascular surgery example in determining the hazard of mortality after the stage 3 Fontan operation associated with prematurity among patients with hypoplastic left heart syndrome who had successful completion of Norwood stage 1 while incorporating mortality during the stage 2 bidirectional Glenn procedure as a competing risk. We apply nonparametric, semiparametric, and parametric methods. RESULTS: Although Cox regression establishes prematurity as a significant risk factor of mortality after stage 3 (hazard ratio, 1.26; 95% confidence interval, 1.06-1.50; P = .009), the competing risks analysis with the Fine-Gray model accounting for mortality after stage 2 determines that prematurity is not a significant predictor (hazard ratio, 1.07; 95% confidence interval, 0.90-1.27; P = .467). CONCLUSIONS: This article provides a practical step-by-step approach for making competing risks more accessible for cardiac surgeons collaborating with a biostatistician in analyzing and interpreting time-to-event data.

149 Fontan Conversions.

Patients with a functionally univentricular heart who have had an atriopulmonary Fontan are at risk for atrial dilatation, atrial arrhythmias, and progressive circulatory failure. Between 1994 and 2018, we performed 149 Fontan conversions with arrhythmia surgery and epicardial pacemaker placement at Ann & Robert H. Lurie Children's Hospital of Chicago. This operation converts the atriopulmonary Fontan to an extracardiac Fontan that improves hemodynamics and controls the atrial arrhythmias. Operative mortality during that time was 2%, and freedom from death or heart transplant at 10 years is 84%. For properly selected patients, Fontan conversion improves both survival and quality of life. Patients with an atriopulmonary Fontan constitute an eroding population, as they face many comorbidities and have a decreased life expectancy without treatment; therefore, all patients with an atriopulmonary Fontan should be evaluated for this procedure.