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Background The objective of this international multicenter study was to investigate both early and late outcomes of cardiac resynchronization therapy (CRT) in patients with a systemic right ventricle (SRV) and to identify predictors for congestive heart failure readmissions and mortality. Methods and Results This retrospective international multicenter study included 13 centers. The study population comprised 80 adult patients with SRV (48.9% women) with a mean age of 45±14 (range, 18-77) years at initiation of CRT. Median follow-up time was 4.1 (25th-75th percentile, 1.3-8.3) years. Underlying congenital heart disease consisted of congenitally corrected transposition of the great arteries and dextro-transposition of the great arteries in 63 (78.8%) and 17 (21.3%) patients, respectively. CRT resulted in significant improvement in functional class (before CRT: III, 25th-75th percentile, II-III; after CRT: II, 25th-75th percentile, II-III; P=0.005) and QRS duration (before CRT: 176±27; after CRT: 150±24 milliseconds; P=0.003) in patients with pre-CRT ventricular pacing who underwent an upgrade to a CRT device (n=49). These improvements persisted during long-term follow-up with a marginal but significant increase in SRV function (before CRT; 30%, 25th-75th percentile, 25-35; after CRT: 31%, 25th-75th percentile, 21-38; P=0.049). In contrast, no beneficial change in the above-mentioned variables was observed in patients who underwent de novo CRT (n=31). A quarter of all patients were readmitted for heart failure during follow-up, and mortality at latest follow-up was 21.3%. Conclusions This international experience with CRT in patients with an SRV demonstrated that CRT in selected patients with SRV dysfunction and pacing-induced dyssynchrony yielded consistent improvement in QRS duration and New York Heart Association functional status, with a marginal increase in SRV function.

Background Ultra-high-density mapping enables detailed mechanistic analysis of atrial reentrant tachycardia but has yet to be used to assess circuit conduction velocity (CV) patterns in adults with congenital heart disease. Methods and Results Circuit pathways and central isthmus CVs were calculated from consecutive ultra-high-density isochronal maps at 2 tertiary centers over a 3-year period. Circuits using anatomic versus surgical obstacles were considered separately and pathway length 85% predicted isthmus block in all cases. Over >1 year of follow-up, arrhythmia-free survival was better for homogeneous CV patterns (90% versus 57%; P=0.04). Conclusions Ultra-high-density mapping-guided CV analysis distinguishes atrial reentrant patterns in adults with congenital heart disease with surgical obstacles producing slower and smaller circuits. Very slow central isthmus CV may be essential for atrial tachycardia maintenance in small circuits, and non-isthmus conduction time in tachycardia appears to be useful for rapid assessment of postablation conduction block.

ObjectivesThis study sought to determine the relationship between long QT syndrome (LQTS) subtype (LTQ1, LTQ2, LTQ3) and postnatal cardiac events (CEs).BackgroundLQTS presenting with 2:1 atrioventricular block or torsades de pointes in the fetus and/or neonate has been associated with risk for major CEs, but overall outcomes and predictors remain unknown.MethodsA retrospective study involving 25 international centers evaluated the course of fetuses/newborns diagnosed with congenital LQTS and either 2:1 atrioventricular block or torsades de pointes. The primary outcomes were age at first CE after dismissal from the newborn hospitalization and death and/or cardiac transplantation during follow-up. CE was defined as aborted cardiac arrest, appropriate shock from implantable cardioverter-defibrillator, or sudden cardiac death.ResultsA total of 84 fetuses and/or neonates were identified with LQTS (12 as LQT1, 35 as LQT2, 37 as LQT3). Median gestational age at delivery was 37 weeks (interquartile range: 35 to 39 weeks) and age at hospital discharge was 3 weeks (interquartile range: 2 to 5 weeks). Fetal demise occurred in 2 and pre-discharge death in 1. Over a median of 5.2 years, there were 1 LQT1, 3 LQT2, and 23 LQT3 CEs (13 aborted cardiac arrests, 5 sudden cardiac deaths, and 9 appropriate shocks). One patient with LQT1 and 11 patients with LQT3 died or received cardiac transplant during follow-up. The only multivariate predictor of post-discharge CEs was LQT3 status (LQT3 vs. LQT2: hazard ratio: 8.4; 95% confidence interval: 2.6 to 38.9; p

Background Patients with Eisenmenger syndrome are known to have a high incidence of sudden cardiac death (SCD), yet the underlying causes are not well understood. We sought to define the predictors of SCD in this population. Methods and Results A retrospective analysis of all patients with Eisenmenger syndrome from 2 large tertiary referral centers was performed. ECGs, prolonged ambulatory recordings, echocardiograms, and clinical histories were reviewed; and the cause of death was identified. A total of 246 patients (85 [34.6%] men) with a mean age of 37.3 (±14.2) years were followed up for a median of 7 years. Over the study period, 136 patients died, with 40 experiencing SCD and 74 experiencing cardiac death (sudden and nonsudden). Age, atrial fibrillation, prolonged QRS duration, complete heart block, right atrial enlargement, right bundle branch block, increased right atrial pressure, impaired biventricular function, and the presence of a pacemaker were associated with increased risk of SCD, whereas advanced pulmonary hypertension therapies were protective. Atrial fibrillation (11.45-fold increased risk; P

Introduction: Optimal treatment strategies for ACHD with AF are unknown. This study sought to assess outcomes of pulmonary vein isolation (PVI) ± left atrial (LA), posterior wall isolation (PWI) for adults with congenital heart disease (ACHD), and atrial fibrillation (AF). Methods: A retrospective review of all cryoballoon (CB) PVI ± PWI procedures at a single center over a 3‐year period were performed. Clinical characteristics and outcomes for patients with and without ACHD were compared. The primary outcome was the occurrence of atrial tachyarrhythmia at 12‐months postablation after a 90‐day blanking period. Results: Three‐hundred and sixteen patients (mean: 63 ± 12 years, [63% male]) underwent CB PVI ± PWI during the study, including 31 (10%) ACHD (simple 35%, moderate 39% complex 26%; nonparoxysmal AF in 52%). ACHD was younger (51 vs. 64 years; p <.001) with a lower CHADS2DS2‐VASc score (1.2 vs. 2.1; p =.001) but had a greater LA diameter (4.9 vs. 4.0 cm; p <.001) and a number of prior cardioversions (0.9 vs. 0.4; p <.001) versus controls. 12‐month freedom from recurrent AF was similar for ACHD and controls (76% vs. 80%; p =.6) and remained nonsignificant in multivariate analysis (hazard ratio: 1.8, 95% confidence interval: 0.7–5.1; p =.22). At 12‐months postablation, 75% of ACHD versus 93% of control patients were off antiarrhythmic drug therapy (p =.07). Conclusion: This study demonstrates younger age and lower conventional stroke risk, yet clinically advanced AF for ACHD relative to controls. CB PVI ± PWI was an effective strategy for the treatment of AF among all forms of ACHD with similar 12‐month outcomes as compared to controls. [ABSTRACT FROM AUTHOR]

Background: Patients with systemic right ventricle (RV) often develop progressive heart failure and may benefit from cardiac resynchronization therapy (CRT); however, the optimal strategy for CRT has not been defined. Methods: A retrospective review of all the patients with systemic RV failure undergoing a hybrid transcatheter‐surgical approach was performed. Procedural technique and outcomes are reported. Results: Six patients underwent detailed electroanatomical mapping of the systemic RV followed by a new hybrid approach targeting latest endocardial activation, which was followed by focused epicardial mapping. The exact site of latest endocardial activation was variable but localized to the basolateral RV in all cases. Sites of latest activation tended to be more superior during contralateral ventricular pacing versus intact atrioventricular conduction (P = 0.06). Latest endocardial activation at the targeted site occurred at 157 ms (interquartile range [IQR] = 120‐181 ms) and corresponding epicardial activation at 174 ms (IQR = 140‐198 ms), after the onset of the QRS complex. Following the hybrid CRT, the QRS duration decreased from a median of 193 to 147 ms and the fractional area of change increased from a median of 15.5% to 30% (P < 0.001). Patients were discharged to home after a median of 4 days. Of the three patients who were initially referred for transplant evaluation, two (66%) of them no longer met the criteria following CRT. Conclusions: Whereas latest endocardial activation for the systemic RV appears to localize to the basolateral region, the optimal lead position may be variable. An approach utilizing endocardial mapping followed by a limited surgical incision and confirmation of latest activation may result in minimally invasive surgery and a favorable acute CRT response. [ABSTRACT FROM AUTHOR]

Objective: Comparative ventricular arrhythmia (VA) outcomes following transcatheter (TC-PVR) or surgical pulmonary valve replacement (S-PVR) have not been evaluated. We sought to compare differences in VAs among patients with congenital heart disease (CHD) following TC-PVR or S-PVR.Methods: Patients with repaired CHD who underwent TC-PVR or S-PVR at the UCLA Medical Center from 2010 to 2016 were analysed retrospectively. Patients who underwent hybrid TC-PVR or had a diagnosis of congenitally corrected transposition of the great arteries were excluded. Patients were screened for a composite of non-intraoperative VA (the primary outcome variable), defined as symptomatic/recurrent non-sustained ventricular tachycardia (VT) requiring therapy, sustained VT or ventricular fibrillation. VA epochs were classified as 0-1 month (short-term), 1-12 months (mid-term) and ≥1 year (late-term).Results: Three hundred and two patients (TC-PVR, n=172 and S-PVR, n=130) were included. TC-PVR relative to S-PVR was associated with fewer clinically significant VAs in the first 30 days after valve implant (adjusted HR 0.20, p=0.002), but similar mid-term and late-term risks (adjusted HR 0.72, p=0.62 and adjusted HR 0.47, p=0.26, respectively). In propensity-adjusted models, S-PVR, patient age at PVR and native right ventricular outflow tract (RVOT) (vs bioprosthetic/conduit outflow tract) were independent predictors of early VA after pulmonary valve implantation (p<0.05 for all).Conclusion: Compared with S-PVR, TC-PVR was associated with reduced short-term but comparable mid-term and late-term VA burdens. Risk factors for VA after PVR included a surgical approach, valve implantation into a native RVOT and older age at PVR. [ABSTRACT FROM AUTHOR]

Abstract: Background: Pediatric heart transplant recipients are at an elevated risk for development of atrial tachycardia (AT); however, the underlying mechanisms and long‐term outcomes are unclear. Objective: We hypothesized that occurrence of AT in pediatric heart transplant recipients would be associated with a higher frequency of adverse events during follow‐up. Methods: A single‐center retrospective review of all pediatric heart transplant recipients with suspected AT between 1997 and 2017 was performed. Unaffected controls were matched with cases for age and transplant era. Clinical characteristics and long‐term outcomes were compared between groups. Results: Of 294 heart transplant recipients, 13 with AT at electrophysiology study (4.4%) were identified and compared with 29 controls. The most common mechanism was focal (11), followed by atrial flutter (two), and electrical reconnection of a surgical atrial anastomosis (two). Focal AT was only observed in the right atrium or atrial septum, and was frequently found on or near the crista terminalis. Relative to controls, cases exhibited more frequent clinical evidence of rejection (9/13 vs 10/29, P  =  0.037). For patients with AT, there was a higher rate of death/retransplant among cases (log‐rank P  =  0.022), which remained significant in multivariate analysis. Conclusion: In this cohort, the most common form of AT after pediatric heart transplantation was focal, with predilection for sites near the crista terminalis. Transplant patients with AT experienced a higher rate of clinical rejection and the composite end‐point of retransplantation or death relative to unaffected controls. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The bidirectional Glenn operation for congenital heart disease produces anatomical constraints to conventional transvenous pacemaker implantation. An iliac approach, although not previously described in this population, is potentially a preferable alternative to a thoracotomy for epicardial pacing. Methods and results: A single‐center retrospective review was performed for all patients that underwent transvenous pacemaker implantation following the bidirectional Glenn operation with partial biventricular repair. Follow‐up data, implant indications, and techniques were recorded. Five patients underwent a transvenous iliac approach (median age 26.9 years, interquartile range [IQR] 25.8–27.6). Pacing indications included AV block in 3 patients (2 requiring cardiac resychronization therapy) and sinus node dysfunction in 2. Implanted leads were atrial in 4 and ventricular in 3 (1 of the latter was placed in the coronary sinus). In two cases, transvenous leads were tunneled to a preexisting epicardial abdominal generator. Median follow‐up was 4.1 years (range 1.0–16.7 years). One patient underwent device revision for lead position‐related groin discomfort; a second patient developed atrial lead failure following a Maze operation and underwent lead replacement by the iliac approach. Patients were not routinely anticoagulated postprocedure given lead position in the subpulmonary circulation. At last follow‐up, all patients were alive. One patient underwent heart transplantation 6 months after implant with only partial resolution of pacing‐induced cardiomyopathy. Conclusions: Trans‐iliac pacemaker placement may be an effective alternative to surgery for patients requiring permanent pacing after the Glenn operation. [ABSTRACT FROM AUTHOR]

Background: Data on atrial fibrillation (AF) ablation and outcomes are limited in patients with congenital heart disease (CHD). We aimed to investigate the characteristics of patients with CHD presenting for AF ablation and their outcomes.Methods: A multicenter, retrospective analysis was performed of patients with CHD undergoing AF ablation between 2004 and 2020 at 13 participating centers. The severity of CHD was classified using 2014 Pediatric and Congenital Electrophysiology Society/Heart Rhythm Society guidelines. Clinical data were collected. One-year complete procedural success was defined as freedom from atrial tachycardia or AF in the absence of antiarrhythmic drugs or including previously failed antiarrhythmic drugs (partial success).Results: Of 240 patients, 127 (53.4%) had persistent AF, 62.5% were male, and mean age was 55.2±13.3 years. CHD complexity categories included 147 (61.3%) simple, 68 (28.3%) intermediate, and 25 (10.4%) severe. The most common CHD type was atrial septal defect (n=78). More complex CHD conditions included transposition of the great arteries (n=14), anomalous pulmonary veins (n=13), tetralogy of Fallot (n=8), cor triatriatum (n=7), single ventricle physiology (n=2), among others. The majority (71.3%) of patients had trialed at least one antiarrhythmic drug. Forty-six patients (22.1%) had reduced systemic ventricular ejection fraction <50%, and mean left atrial diameter was 44.1±8.2 mm. Pulmonary vein isolation was performed in 227 patients (94.6%); additional ablation included left atrial linear ablations (40%), complex fractionated atrial electrogram (19.2%), and cavotricuspid isthmus ablation (40.8%). One-year complete and partial success rates were 45.0% and 20.5%, respectively, with no significant difference in the rate of complete success between complexity groups. Overall, 38 patients (15.8%) required more than one ablation procedure. There were 3 (1.3%) major and 13 (5.4%) minor procedural complications.Conclusions: AF ablation in CHD was safe and resulted in AF control in a majority of patients, regardless of complexity. Future work should address the most appropriate ablation targets in this challenging population. [ABSTRACT FROM AUTHOR]

Background: Palliation of the single ventricle (SV) circulation is associated with a burden of lifelong complications. Previous studies have identified that the need for a permanent ventricular pacing system (PPMv) may be associated with additional adverse long-term outcomes.Objectives: The goal of this study was to quantify the attributable risk of PPMv in patients with SV, and to identify modifiable risk factors.Methods: This international study was sponsored by the Pediatric and Congenital Electrophysiology Society. Centers contributed baseline and longitudinal data for functionally SV patients with PPMv. Enrollment was at implantation. Controls were matched 1:1 to PPMv subjects by ventricular morphology and sex, identified within center, and enrolled at matched age. Primary outcome was transplantation or death.Results: In total, 236 PPMv subjects and 213 matched controls were identified (22 centers, 9 countries). Median age at enrollment was 5.3 years (quartiles: 1.5-13.2 years), follow-up 6.9 years (3.4-11.6 years). Median percent ventricular pacing (Vp) was 90.8% (25th-75th percentile: 4.3%-100%) in the PPMv cohort. Across 213 matched pairs, multivariable HR for death/transplant associated with PPMv was 3.8 (95% CI 1.9-7.6; P < 0.001). Within the PPMv population, higher Vp (HR: 1.009 per %; P = 0.009), higher QRS z-score (HR: 1.19; P = 0.009) and nonapical lead position (HR: 2.17; P = 0.042) were all associated with death/transplantation.Conclusions: PPMv in patients with SV is associated with increased risk of heart transplantation and death, despite controlling for increased associated morbidity of the PPMv cohort. Increased Vp, higher QRS z-score, and nonapical ventricular lead position are all associated with higher risk of adverse outcome and may be modifiable risk factors. [ABSTRACT FROM AUTHOR]