Clinical Course Long After Atrial Switch: A Novel Risk Score for Major Clinical Events

External Validation of a Risk Score Model for Predicting Major Clinical Events in Adults After Atrial Switch

BACKGROUND

A risk model has been proposed to provide a patient individualized estimation of risk for major clinical events (heart failure events, ventricular arrhythmia, all-cause mortality) in patients with transposition of the great arteries and atrial switch surgery. We aimed to externally validate the model.

METHODS AND RESULTS

A retrospective, multicentric, longitudinal cohort of 417 patients with transposition of the great arteries (median age, 24 years at baseline [interquartile range, 18-30]; 63% men) independent of the model development and internal validation cohort was studied. The performance of the prediction model in predicting risk at 5 years was assessed, and additional predictors of major clinical events were evaluated separately in our cohort. Twenty-five patients (5.9%) met the major clinical events end point within 5 years. Model validation showed good discrimination between high and low 5-year risk patients (Harrell C index of 0.73 [95% CI, 0.65-0.81]) but tended to overestimate this risk (calibration slope of 0.20 [95% CI, 0.03-0.36]). In our population, the strongest independent predictors of major clinical events were a history of heart failure and at least mild impairment of the subpulmonary left ventricle function.

CONCLUSIONS

We reported the first external validation of a major clinical events risk model in a large cohort of adults with transposition of the great arteries. The model allows for distinguishing patients at low risk from those at intermediate to high risk. Previous episode of heart failure and subpulmonary left ventricle dysfunction appear to be key markers in the prognosis of patients. Further optimizing risk models are needed to individualize risk predictions in patients with transposition of the great arteries.

Long-term outcome of patients with transposition of the great arteries and a systemic right ventricle: A systematic review and meta-analysis

BACKGROUND

Patients with a transposition of the great arteries (TGA) and a systemic right ventricle are at risk of heart failure (HF) development, arrhythmia and early mortality. Prognostic evaluations in clinical studies are hampered by small sample sizes and single-centred approaches. We aimed to investigate yearly rate of outcome and factors affecting it.

METHODS

A systematic literature search of four electronic databases (PubMed, EMBASE, Web of Science and Scopus) was conducted from inception to June 2022. Studies reporting the association of a systemic right ventricle with mortality with a minimal follow-up of 2 years during adulthood were selected. Incidence of HF hospitalization and/or arrhythmia were captured as additional endpoints. For each outcome, a summary effect estimate was calculated.

RESULTS

From a total of 3891 identified records, 56 studies met the selection criteria. These studies described the follow-up (on average 7.27 years) of 5358 systemic right ventricle patients. The mortality incidence was 1.3 (1-1.7) per 100 patients/year. The incidence of HF hospitalization was 2.6 (1.9-3.7) per 100 patients/year. Predictors of poor outcome were a lower left ventricular (LV) and right ventricular ejection fraction (RVEF) (standardized mean differences (SMD) of -0.43 (-0.77 to -0.09) and - 0.85 (-1.35 to -0.35), respectively), higher plasma concentrations of NT-proBNP (SMD of 1.24 (0.49-1.99)), and NYHA class ≥2 (risk ratio of 2.17 (1.40-3.35)).

CONCLUSIONS

TGA patients with a systemic right ventricle have increased incidence of mortality and HF hospitalization. A lower LVEF and RVEF, higher levels of NT-proBNP and NYHA class ≥2 are associated with poor outcome.

Valvular Regurgitation in Adults with Congenital Heart Disease and Heart Failure: Current Status and Potential Interventions

The great majority of patients born with congenital heart disease (CHD) are living well into adulthood, yet they often have residual hemodynamic lesions, including valvar regurgitation. As these complex patients grow older, they are at risk of developing heart failure, which can be exacerbated by the underlying valvular regurgitation. In this review, we describe the etiologies of heart failure related to valvular regurgitation in the CHD population and discuss potential interventions.

Overview of Long-Term Outcome in Adults with Systemic Right Ventricle and Transposition of the Great Arteries: A Review

The population of patients with a systemic right ventricle (sRV) in biventricular circulation includes those who have undergone an atrial switch operation for destro-transposition of the great arteries (d-TGA) and those with congenitally corrected transposition of the great arteries (ccTGA). Despite the life expectancy of these patients is significantly increased, the long-term prognosis remains suboptimal due to late complications such as heart failure, arrhythmias, and premature death. These patients, therefore, need a close follow-up to early identify predictive factors of adverse outcomes and to implement all preventive therapeutic strategies. This review analyzes the late complications of adult patients with an sRV and TGA and clarifies which are risk factors for adverse prognosis and which are the therapeutic strategies that improve the long-term outcomes. For prognostic purposes, it is necessary to monitor sRV size and function, the tricuspid valve regurgitation, the functional class, the occurrence of syncope, the QRS duration, N-terminal pro B-type natriuretic peptide levels, and the development of arrhythmias. Furthermore, pregnancy should be discouraged in women with risk factors. Tricuspid valve replacement/repair, biventricular pacing, and implantable cardioverter defibrillator are the most important therapeutic strategies that have been shown, when used correctly, to improve long-term outcomes.

The potential of sodium-glucose cotransporter 2 inhibitors for the treatment of systemic right ventricular failure in adults with congenital heart disease

Aims

Given the compelling evidence on the effectiveness of sodium-glucose cotransporter 2 inhibitors (SGLT2i) in the conventional heart failure population, SGLT2i deserve exploration in systemic right ventricular (sRV) failure. The initial experience with dapagliflozin in sRV failure patients is described, with a focus on tolerability and short-term effects on clinical outcomes.

Methods and results

Ten patients (70% female, median age 50 years [46.5-52]) with symptomatic sRV failure who received dapagliflozin 10 mg per day on top of optimal medical therapy between 04-2021 and 01-2023 were included. Within 4 weeks, no significant changes in blood pressure, electrolytes, or serum glucose occurred. Creatinine and estimated glomerular filtration rate (eGFR) showed a slight decline (88 ± 17 to 97 ± 23 µmol/L, p = 0.036, and 72 ± 14 vs. 66 ± 16 ml/min/1.73m2, p = 0.020, respectively). At 6 months follow-up (n = 8), median NT-proBNP decreased significantly from 736.6 [589.3-1193.3] to 531.6 [400.8-1018] ng/L (p = 0.012). Creatinine and eGFR recovered to baseline levels. There were no significant changes in echocardiographic systolic sRV or left ventricular function. New York Heart Association class improved significantly in 4 out of 8 patients (p = 0.046), who also showed an improvement in the 6-minute walk test or bicycle exercise test performance. One female patient developed an uncomplicated urinary tract infection. No patients discontinued treatment.

Conclusion

Dapagliflozin was well-tolerated in this small cohort of sRV failure patients. While the early results on the reduction of NT-proBNP and clinical outcome parameters are encouraging, large-scale prospective studies are warranted to thoroughly evaluate the effects of SGLT2i in the growing sRV failure population.

Cardiac Fibrosis and Innervation State in Uncorrected and Corrected Transposition of the Great Arteries: A Postmortem Histological Analysis and Systematic Review

In the transposition of the great arteries (TGA), alterations in hemodynamics and oxygen saturation could result in fibrotic remodeling, but histological studies are scarce. We aimed to investigate fibrosis and innervation state in the full spectrum of TGA and correlate findings to clinical literature. Twenty-two human postmortem TGA hearts, including TGA without surgical correction (n = 8), after Mustard/Senning (n = 6), and arterial switch operation (ASO, n = 8), were studied. In newborn uncorrected TGA specimens (1 day-1.5 months), significantly more interstitial fibrosis (8.6% ± 3.0) was observed compared to control hearts (5.4% ± 0.8, p = 0.016). After the Mustard/Senning procedure, the amount of interstitial fibrosis was significantly higher (19.8% ± 5.1, p = 0.002), remarkably more in the subpulmonary left ventricle (LV) than in the systemic right ventricle (RV). In TGA-ASO, an increased amount of fibrosis was found in one adult specimen. The amount of innervation was diminished from 3 days after ASO (0.034% ± 0.017) compared to uncorrected TGA (0.082% ± 0.026, p = 0.036). In conclusion, in these selected postmortem TGA specimens, diffuse interstitial fibrosis was already present in newborn hearts, suggesting that altered oxygen saturations may already impact myocardial structure in the fetal phase. TGA-Mustard/Senning specimens showed diffuse myocardial fibrosis in the systemic RV and, remarkably, in the LV. Post-ASO, decreased uptake of nerve staining was observed, implicating (partial) myocardial denervation after ASO.

Echo-Doppler and strain assessment of filling pressures in adults with congenitally corrected transposition and systemic right ventricles

AIMS

Systolic dysfunction of the systemic right ventricle (sRV) is common in adults with transposition of the great arteries and sRV. In acquired disease, diastology analysis for assessment of filling pressures (FP) is paramount in patient care.

METHODS AND RESULTS

Retrospective analysis of 47 adults with sRV without prior systemic tricuspid valve surgery undergoing catheterization and echocardiography within 7 days (median -2 [-1, -3]) from January 2000 to February 2021 at our institution. Median age was 48 (31, 55) years, and 16 (34.0%) patients were female. FPs were normal in 21 patients (44.7%). Left atrial size was enlarged in most patients (83.0%) with mean indexed value 58.3 ± 23.4 mL/m2. Tissue Doppler e' was not significantly different between those with high FPs vs. normal (medial 0.07 ± 0.03 vs. 0.08 ± 0.03 m/s, P = 0.63; lateral 0.08 ± 0.04 vs. 0.08 ± 0.04 m/s, P = 0.88). E velocity and subpulmonic mitral regurgitant velocity were higher in those with high FPs (0.9 ± 0.3 vs. 0.6 ± 0.2 m/s, P = 0.005; 3.8 ± 1.1 vs. 2.8 ± 0.9 m/s, P = 0.004). Left atrial reservoir strain, sRV global longitudinal strain, and subpulmonic left ventricular strain were worse in those with high FP (18.0 ± 7.6 vs. 27.9 ± 10.2%, P = 0.0009; -13.0 ± 4.4 vs. -17.9 ± 5.0%, P = 0.002; -16.8 ± 5.7 vs. -23.0 ± 3.8%, P = 0.001).

CONCLUSION

Despite the complex anatomy, FPs can be assessed non-invasively in adults with sRV without prior systemic tricuspid valve surgery. The current guideline algorithm for diastolic dysfunction in acquired heart disease has limited applicability in this population. Given the limitations of Doppler in this heterogeneous population, strain analysis can be a helpful adjunct for estimation of FPs.

Contemporary Management Strategies of Baffle Leaks in Adults with a Failing Systemic Right Ventricle Late after Atrial Switch: A Case Series and Literature Overview

Baffle leaks are a frequently encountered and often overlooked complication after the atrial switch procedure for transposition of the great arteries. Baffle leaks are present in up to 50% of non-selected patients, and while they initially may not cause clear symptoms, they can complicate the hemodynamic course and influence the prognosis in this complex patient group. A shunt from the pulmonary venous atrium (PVA) to the systemic venous atrium (SVA) can lead to pulmonary overflow and subpulmonary left ventricular (LV) volume overload, while a shunt from the SVA to the PVA can result in (exercise-associated) cyanosis and paradoxical embolism. We report three cases of baffle leaks in patients with systemic right ventricular (sRV) failure late after the atrial switch procedure. Two symptomatic patients who presented with exercise-associated cyanosis due to SVA to PVA shunting over the baffle leak underwent successful percutaneous baffle leak closure with a septal occluder device. One patient with overt sRV failure and signs of subpulmonary LV volume overload due to PVA to SVA shunting was managed conservatively, as baffle leak closure was expected to lead to an increase in sRV end-diastolic pressure and aggravation of sRV dysfunction. These three cases illustrate the considerations made, challenges faced, and necessity of a patient-tailored approach when addressing baffle leaks.

Common genetic variants improve risk stratification after the atrial switch operation for transposition of the great arteries

BACKGROUND

Clinical factors are used to estimate late complication risk in adults after atrial switch operation (AtrSO) for transposition of the great arteries (TGA), but heterogeneity in clinical course remains. We studied whether common genetic variants are associated with outcome and add value to a clinical risk score in TGA-AtrSO patients.

METHODS AND RESULTS

This multicenter study followed 133 TGA-AtrSO patients (aged 28 [IQR 24-35] years) for 13 (IQR 9-16) years and examined the association of genome-wide single-nucleotide polymorphisms (SNPs) with a composite endpoint of symptomatic ventricular arrhythmia, heart failure hospitalization, ventricular assist device implantation, heart transplantation, or mortality. Thirty-two patients (24%) reached the endpoint. The genome-wide association study yielded one genome-wide significant (p < 1 × 10^-8) locus and 18 suggestive loci (p < 1 × 10^-5). A genetic risk score constructed on the basis of independent SNPs with p < 1 × 10^-5 was associated with outcome after correction for the clinical risk score (HR = 1.26/point increase [95%CI 1.17-1.35]). Risk stratification improved with a combined risk score (clinical score + genetic score) compared to the clinical score alone (p = 2 × 10^-16, C-statistic 0.95 vs 0.85). In 51 patients with a clinical intermediate (5-20%) 5-year risk of events, the combined score reclassified 32 patients to low (<5%) and 5 to high (>20%) risk. Stratified by the combined score, observed 5-year event-free survival was 100%, 79% and 31% for low, intermediate, and high-risk patients, respectively.

CONCLUSIONS

Common genetic variants may explain some variation in the clinical course in TGA-AtrSO and improve risk stratification over clinical factors alone, especially in patients at intermediate clinical risk. These findings support the hypothesis that including genetic variants in risk assessment may be beneficial.

Heart failure in systemic right ventricle: Mechanisms and therapeutic options

d-loop transposition of the great arteries (d-TGA) and congenitally corrected transposition of the great arteries (cc-TGA) feature a right ventricle attempting to sustain the systemic circulation. A systemic right ventricle (sRV) cannot support cardiac output in the long run, eventually decompensating and causing heart failure. The burden of d-TGA patients with previous atrial switch repair and cc-TGA patients with heart failure will only increase in the coming years due to the aging adult congenital heart disease population and improvements in the management of advanced heart failure. Clinical data still lags behind in developing evidence-based guidelines for risk stratification and management of sRV patients, and clinical trials for heart failure in these patients are underrepresented. Recent studies have provided foundational data for the commencement of robust clinical trials in d-TGA and cc-TGA patients. Further insights into the multifactorial nature of sRV failure can only be provided by the results of such studies. This review discusses the mechanisms of heart failure in sRV patients with biventricular circulation and how these mediators may be targeted clinically to alleviate sRV failure.

The Ventricular Switch: An Alternative Strategy Toward Biventricular Repair in Moderately Hypoplastic Left Ventricles or Complex Connections

Hypoplastic left heart complex (HLHC) constitutes a spectrum of left ventricular hypoplasia and valvar disease and can be associated with increased morbidity and mortality. Traditionally, management of these lesions involves single ventricle palliation (SVP). However, the SVP may be associated with substantial long-term consequences related to its physiology. Alternative management strategies have been employed to achieve biventricular circulation. We have proposed a novel technique, termed the "ventricular switch" procedure, in which the hypoplastic or unroutable left ventricle can be harnessed to function as the subpulmonic ventricle, and the right ventricle functions as the systemic ventricle. Herein, we describe our rationale for considering biventricular circulation and the ventricular switch procedure in HLHC and in other complex lesions.

Atrioventricular Block Necessitating Chronic Ventricular Pacing After Tricuspid Valve Surgery in Patients With a Systemic Right Ventricle: Long-Term Follow-Up

Background

Patients with transposition of the great arteries (TGA) after an atrial switch or congenitally corrected TGA (ccTGA) are prone to systemic right ventricular (sRV) failure. Tricuspid valve (TV) regurgitation aggravates sRV dysfunction. Timely TV surgery stabilizes sRV function, yet the development of atrioventricular (AV)-conduction disturbances in the course of sRV failure can contribute to sRV dysfunction through pacing-induced dyssynchrony. This study aims to explore the incidence, timing, and functional consequences of AV-block requiring ventricular pacing after TV surgery in patients with sRV.

Methods

Consecutive adolescent and adult patients with an sRV who underwent TV surgery between 1989 and 2020 and followed-up at our center were included in this observational cohort study.

Results

The data of 28 patients (53% female, 57% ccTGA, and a mean age at surgery 38 ± 13 years) were analyzed. The mean follow-up was 9.7 ± 6.8 years. Of the remaining 22 patients at the risk of developing high degree AV-block after TV surgery, 9 (41%) developed an indication for chronic ventricular pacing during follow-up, of which 5 (56%) within 24 months postoperatively (3 prior to hospital discharge). The QRS duration, a surrogate marker for dyssynchrony, was significantly higher in patients with chronic left ventricular pacing than in patients with native AV-conduction (217 ± 24 vs. 116 ± 23 ms, p = 0.000), as was the heart failure biomarker NT-pro-BNP [2,746 (1,242–6,879) vs. 495 (355–690) ng/L, p = 0.004] and the percentage of patients with ≥1 echocardiographic class of deterioration of systolic sRV function (27 vs. 83%, p = 0.001). Of the patients receiving chronic subpulmonary ventricular pacing (n = 12), 9 (75%) reached the composite endpoint of progressive heart failure [death, ventricular assist device implantation, or upgrade to cardiac resynchronization therapy (CRT)]. Only 4 (31%) patients with native AV-conduction (n = 13) reached this composite endpoint (p = 0.027).

Conclusion

Patients with a failing sRV who undergo TV surgery are prone to develop AV-conduction abnormalities, with 41% developing an indication for chronic ventricular pacing during 10 years of follow-up. Patients with chronic subpulmonary ventricular pacing have a significantly longer QRS complex duration, have higher levels of the heart failure biomarker NT-pro-BNP, and are at a higher risk of deterioration of systolic sRV function and progressive heart failure.

The first experience with sodium-glucose cotransporter 2 inhibitor for the treatment of systemic right ventricular failure

In congenitally corrected transposition of the great arteries, the morphological right ventricle supports the systemic circulation. This chronic exposure to pressure overload ultimately leads to systemic right ventricular (sRV) dysfunction and heart failure. Pharmacological options for the treatment of sRV failure are poorly defined and no solid recommendations are made in the most recent guidelines. Sodium-glucose cotransporter 2 (SGLT-2) inhibitors are a new class of antihyperglycaemic drugs that have been demonstrated to significantly reduce the risk of worsening heart failure and death from cardiovascular causes in patients with chronic heart failure with reduced left ventricular ejection fraction, yet no data are available in sRV patients. We report on the treatment and clinical follow-up of a patient with advanced heart failure and poor sRV function in the context of congenitally corrected transposition of the great arteries, who did not tolerate sacubitril/valsartan and had a high burden of heart-failure-related hospitalizations. Treatment with dapagliflozin was well tolerated and resulted in (small) subjective and objective functional and echocardiographic improvement and a reduction in heart-failure-related hospitalizations.

Clinical Course Long After Atrial Switch: A Novel Risk Score for Major Clinical Events

Background

Patients with transposition of the great arteries corrected by an atrial switch operation experience major clinical events during adulthood, mainly heart failure (HF) and arrhythmias, but data on the emerging risks remain scarce. We assessed the risk for events during the clinical course in adulthood, and provided a novel risk score for event‐free survival.

Methods and Results

This multicenter study observed 167 patients with transposition of the great arteries corrected by an atrial switch operation (61% Mustard procedure; age, 28 [interquartile range, 24–36] years) for 13 (interquartile range, 9–16) years, during which 16 (10%) patients died, 33 (20%) had HF events, defined as HF hospitalizations, heart transplantation, ventricular assist device implantation, or HF‐related death, and 15 (9%) had symptomatic ventricular arrhythmias. Five‐year risk of mortality, first HF event, and first ventricular arrhythmia increased from 1% each at age 25 years, to 6% (95% CI, 4%–9%), 23% (95% CI, 17%–28%), and 5% (95% CI, 2%–8%), respectively, at age 50 years. Predictors for event‐free survival were examined to construct a prediction model using bootstrapping techniques. A prediction model combining age >30 years, prior ventricular arrhythmia, age >1 year at repair, moderate or greater right ventricular dysfunction, severe tricuspid regurgitation, and mild or greater left ventricular dysfunction discriminated well between patients at low (<5%), intermediate (5%–20%), and high (>20%) 5‐year risk (optimism‐corrected C‐statistic, 0.86 [95% CI, 0.82–0.90]). Observed 5‐ and 10‐year event‐free survival rates in low‐risk patients were 100% and 97%, respectively, compared with only 31% and 8%, respectively, in high‐risk patients.

Conclusions

The clinical course of patients undergoing atrial switch increasingly consists of major clinical events, especially HF. A novel risk score stratifying patients as low, intermediate, and high risk for event‐free survival provides information on absolute individual risks, which may support decisions for pharmacological and interventional management.