Ventricular Arrhythmias in Adults With Congenital Heart Disease, Part II: JACC State-of-the-Art Review

There are marked variations in the incidence of sudden cardiac death (SCD) and in the substrates for ventricular arrhythmias (VAs) across the gamut of congenital heart defects. In this 2-part review, patients with higher-risk forms of congenital heart disease (CHD) were conceptually categorized into those with discrete anatomic isthmuses for macro-reentrant ventricular tachycardia (VT) (Group A) and those with more diffuse or less well-defined substrates (Group B) that include patchy or extensive myocardial fibrosis. The latter category encompasses CHD lesions such as Ebstein anomaly, transposition of the great arteries with a systemic right ventricle (RV), and congenital aortic stenosis. For Group B patients, polymorphic VT and ventricular fibrillation account for a higher proportion of VA. The prognostic value of programmed ventricular stimulation is less well established, and catheter ablation plays a less prominent role. As cardiomyopathies evolve over time, pathophysiological mechanisms for VA among Groups A and B become increasingly blurred.

Usefulness of insertable cardiac monitors for risk stratification: current indications and clinical evidence

INTRODUCTION

The 2018 ESC Syncope guidelines expanded the indications for an insertable cardiac monitor (ICM) to patients with unexplained syncope and primary cardiomyopathy or inheritable arrhythmogenic disorders.

AREAS COVERED

This review article discusses the clinical evidence for using an ICM for risk stratification in different patient populations including Brugada syndrome, long QT syndrome, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, cardiac sarcoidosis, and congenital heart disease.

EXPERT OPINION

Clinical data on the usefulness of ICMs in different patient populations is limited but most studies demonstrate early detection of clinically relevant arrhythmias, such as nonsustained ventricular tachycardia or atrial fibrillation. It is important to emphasize that the study populations usually comprise selected populations where conventional diagnostic methods fail to clarify the mechanism of symptoms. The effect of an ICM on prognosis by earlier detection of arrhythmias is difficult to demonstrate in populations with rare disease. Risk stratification in patients with cardiomyopathy or inheritable arrhythmogenic disorders remains a niche indication for ICMs. The most important indication for an ICM remains unexplained syncope in patients at low risk of SCD. Given the device costs and uncertain clinical value of device-detected arrhythmias, it is unclear whether it is also useful in non-syncopal patients.

A case report of paroxysmal complete atrioventricular block in a patient with dextrocardia and repaired tetralogy of Fallot

BACKGROUND

Some adults suffer sudden cardiac death after previous surgical repair of tetralogy of Fallot (TOF), and in such cases, ventricular tachycardia is believed to be the most frequent cause of death. However, we report a case of cardiac arrest due to paroxysmal complete atrioventricular block in an adult with dextrocardia and repaired TOF.

CASE SUMMARY

A 49-year-old woman with dextrocardia and a history of surgical treatment for TOF lost consciousness three times. A previously implanted loop recorder showed a 60-second cardiac arrest, and complete atrioventricular block was diagnosed. An electrophysiological study showed prolongation of the His-ventricular interval but no ventricular tachycardia. A dual chamber pacemaker was implanted, and there has been no recurrence of syncope in the 23 months since implantation.

DISCUSSION

There is little evidence for paroxysmal complete atrioventricular block in patients with repaired TOF. This case suggests that paroxysmal complete atrioventricular block can occur late after surgical repair of TOF, and research needs to elucidate whether it is the cause of sudden cardiac death in some patients with TOF.

Avalanches in cardiology

Sudden cardiac death (SCD) accounts for 15%–60% of mortality in patients with heart disease. Generally, this has been attributed to ventricular tachyarrhythmia. However, ventricular tachyarrhythmia has been documented or strongly suspected on clinical grounds in a relatively small proportion of SCD patients (8%–50%). Attempted prophylaxis of SCD by implantation of cardioverter-defibrillator is associated with variable success in different subsets of high-risk cardiac patients (30%–70%). A significant number of SCD, therefore, appear to be due to catastrophic circulatory failure. Multiple interdependent compensatory mechanisms help to maintain circulation in advanced cardiac disease. Rapid, unexpected, and massive breakdown of the compensated state can be precipitated by small and often imperceptible triggers. The initial critical but stable state followed by rapid circulatory failure and death has been considered to be analogous to snow avalanches. It is typically described in patients with left ventricular (LV) dysfunction (ischemic or nonischemic). It is now recognized that SCD can also happen in conditions where the right ventricle (RV) takes the brunt of the hemodynamic load. Advanced pulmonary arterial hypertension and operated patients of tetralogy of Fallot with pulmonary regurgitation are of particular interest to pediatric cardiologists. A large amount of data is available on LV changes and mechanics, while relatively little information is available on the mechanisms of RV adaptation to increased load and RV failure. Whether the triggers and the decompensatory processes are similar for the two ventricles is a moot point. This article highlights the currently available knowledge on the pathophysiology of SCD in RV overload states, with special reference to RV adaptive and decompensatory mechanisms, and therapeutic measures that can potentially interrupt the vicious downward course (cardiac avalanches).

Early detection of ventricular arrhythmias in adults with congenital heart disease using an insertable cardiac monitor (EDVA-CHD study)

BACKGROUND

Sudden cardiac death (SCD) due to ventricular arrhythmias (VA) is an important mode of death in adults with congenital heart disease (CHD). Risk stratification is difficult in this heterogeneous population. Insertable cardiac monitors (ICM) may be useful for risk stratification. The purpose of the present study was to evaluate the use of ICM for the detection of VA in adults with CHD.

METHODS

In this prospective single-center observational study we included consecutive adults with CHD deemed at risk of VA who received an ICM between March 2013 and February 2019. The decision to implant an ICM was made in a Heart Team consisting of a cardiac electrophysiologist and a cardiologist specialized in CHD.

RESULTS

A total of 30 patients (mean age, 38 ± 15 years; 50% male) received an ICM. During a median follow-up of 16 months, 8 patients (27%) had documented nonsustained VA. Of these 8 patients, 3 (10%) received a prophylactic ICD. Furthermore, ICM-detected arrhythmias were present in 22 patients (73%) leading to a change in clinical management in 16 patients (53%). Besides the patients receiving an ICD, 10 patients (33%) had a change in their antiarrhythmic drugs, 6 patients (20%) underwent an electrophysiology study, and 1 patient (3%) received a pacemaker.

CONCLUSIONS

The detection of VA by the ICM contributed to the clinical decision to implant a prophylactic ICD. Furthermore, ICM-detected arrhythmias led to important changes in the clinical management. Therefore, long-term arrhythmia monitoring by an ICM seems valuable for risk stratification in adults with CHD.

[Adult congenital heart disease: Medical and psychosocial issues]

The population of adults with congenital heart disease (ACHD) is continuously increasing with now a higher prevalence than that of the pediatric population. This concerns above all complex congenital heart diseases. Heart failure is the primary cause of death followed by arrhythmia, which is very common in ACHD. A specialized follow-up by dedicated centers is significantly associated with an improvement of survival of ACHD patients compared to non-expert follow-up. Extracardiac disorders (liver, kidney, respiratory) are frequent and require an accurate and specific management. The psychosocial impact, particularly the professional difficulties, is common and may require implementation of appropriate measures to improve the patient social life. Unplanned pregnancy and/or a lack of information about contraception may induce severe cardiovascular complications in ACHD women. Education about contraceptive methods at adolescence and pre-conceptional counseling are requested in this population.

Health in adults with congenital heart disease

Since the introduction of cardiac surgery, the prospects for children born with a cardiac defect have improved spectacularly. Many reach adulthood and the population of adults with congenital heart disease is increasing and ageing. However, repair of congenital heart disease does not mean cure. Many adults with congenital heart disease encounter late complications. Late morbidity can be related to the congenital heart defect itself, but may also be the consequence of the surgical or medical treatment or longstanding alterations in hemodynamics, neurodevelopment and psychosocial development. This narrative review describes the cardiac and non-cardiac long-term morbidity in the adult population with congenital heart disease.

Acute phase proteins altered in the plasma of patients with congenital ventricular septal defect

PURPOSE

Ventricular septal defect (VSD) has intracardiac left-to-right shunt and increased pulmonary flow that may affect the acute phase response (APR). We examined the hypothesis that plasma proteins of VSD patients may be altered.

EXPERIMENTAL DESIGN

2DE and MS were used to detect differential plasma proteins in VSD patients (n = 55) and controls (n = 70). Candidate APR proteins were confirmed by ELISA in new samples.

RESULTS

Among three differentially expressed APR proteins from 322 protein spots detected, haptoglobin (0.4 ± 0.04 versus 0.6 ± 0.07 mg/mL; p = 0.016) and serum amyloid P-component (SAP) (3.8 ± 0.2 versus 6.3 ± 0.8 ng/mL; p = 0.003) were significantly lower and orosomucoid 2 (3.1 ± 0.1 mg/mL versus 2.3 ± 0.1 mg/mL; p < 0.001) was significantly higher in VSD patients than in normal controls.

CONCLUSIONS AND CLINICAL RELEVANCE

The plasma concentration of three acute phase proteins, haptoglobin, SAP, and orosomucoid 2 are altered that may reflect inflammation, be associated with decreased innate immune system function, and predispose the VSD patients to vulnerability to infections and pulmonary disease. These three proteins in plasma may also be developed as biomarkers for the function of innate immune system in patients with congenital heart disease.

Utility of noninvasive arrhythmia mapping in patients with adult congenital heart disease

Arrhythmia management in patients with adult congenital heart disease (ACHD) is a challenge on many levels, as tachycardic episodes may lead to hemodynamic impairment in otherwise compensated patients even if episodes are only transient. Recently several technical advances, including 3-dimensional (3D) image integration, 3D mapping, and remote magnetic navigation, have been introduced to facilitate curatively intended ablation procedures in patients with ACHD. This review attempts to outline the role of a novel technology of simultaneous, noninvasive mapping in this patient cohort, and gives details of the authors' single-center experience.

Mutation spectrum of GATA4 associated with congenital atrial septal defects

INTRODUCTION

Congenital atrial septal defect (ASD) is the second commonest form of cardiac developmental anomaly, responsible for substantial morbidity and mortality in affected individuals. Previous studies have implicated genetic defects in the pathogenesis of ASD. However, ASD is largely a genetically heterogeneous disease and the genetic determinants for ASD in the majority of patients remain to be identified.

MATERIAL AND METHODS

The entire coding region of GATA4, a gene encoding a zinc-finger transcription factor essential for normal cardiac morphogenesis, was sequenced in 220 unrelated patients with ASD. The available relatives of the patients harboring the identified mutations and 200 unrelated ethnicity-matched control individuals were genotyped.

RESULTS

Four heterozygous missense GATA4 mutations, p.P36S, p.H190R, p.S262A, and p.V399G, were identified in four unrelated patients with ASD, respectively. These mutations were neither detected in 200 control individuals nor described in the human SNP database. Alignment of multiple GATA4 protein sequences across species indicated that the affected amino acids were highly conserved evolutionarily. Genetic analysis of the available relatives of the mutation carriers showed that in each family the mutation co-segregated with ASD.

CONCLUSIONS

The findings expand the spectrum of mutations in GATA4 linked to ASD and provide new insight into the molecular etiology associated with ASD, suggesting the potential implications for the genetic diagnosis and gene-specific therapy for this prevalent cardiovascular abnormality in humans.

Cytoplasm resistivity of mammalian atrial myocardium determined by dielectrophoresis and impedance methods

Many cardiac arrhythmias are caused by slowed conduction of action potentials, which in turn can be due to an abnormal increase of intracellular myocardial resistance. Intracellular resistivity is a linear sum of that offered by gap junctions between contiguous cells and the cytoplasm of the myocytes themselves. However, the relative contribution of the two components is unclear, especially in atrial myocardium, as there are no precise measurements of cytoplasmic resistivity, R(c). In this study, R(c) was measured in atrial tissue using several methods: a dielectrophoresis technique with isolated cells and impedance measurements with both isolated cells and multicellular preparations. All methods yielded similar values for R(c), with a mean of 138 ± 5 Ω·cm at 23°C, and a Q(10) value of 1.20. This value is about half that of total intracellular resistivity and thus will be a significant determinant of the actual value of action potential conduction velocity. The dielectrophoresis experiments demonstrated the importance of including divalent cations (Ca(2+) and Mg(2+)) in the suspension medium, as their omission reduced cell integrity by lowering membrane resistivity and increasing cytoplasm resistivity. Accurate measurement of R(c) is essential to develop quantitative computational models that determine the key factors contributing to the development of cardiac arrhythmias.

Sudden Cardiac Death in Adult Congenital Heart Disease

Background—

Sudden cardiac death (SCD) is a major cause of mortality in adults with congenital heart disease (CHD). The aim of this study was to determine the adult CHD population at risk of SCD and the clinical parameters associated with SCD.

Methods and Results—

We performed a multicenter case-control study. Patients who died suddenly as a result of proven or presumed arrhythmia were included (cases). For each case, 2 controls matched on diagnosis, type of surgical intervention, age, and gender were included. From 3 databases including 25 790 adults with CHD, 1189 deaths (5%) were identified, of whom 213 patients (19%) died suddenly. Arrhythmic death occurred in 171 of 1189 patients. The underlying cardiac lesions were mild, moderate, and severe CHD in 12%, 33%, and 55% of the SCD cases, respectively. Clinical variables associated with SCD were supraventricular tachycardia (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.5–7.9; P= 0.004), moderate to severe systemic ventricular dysfunction (OR, 3.4; 95% CI, 1.1–10.4; P= 0.034), moderate to severe subpulmonary ventricular dysfunction (OR, 3.4; 95% CI, 1.1–10.2; P= 0.030), increased QRS duration (OR, 1.34 [per 10-ms increase]; 95% CI, 1.10–1.34; P =0.008), and QT dispersion (OR, 1.22 [per 10-ms increase]; 95% CI, 1.22–1.48; P =0.008).

Conclusions—

The clinical parameters found to be associated with SCD in adults with a broad spectrum of CHD, including systemic right ventricles, are similar to those in ischemic heart disease. Moreover, even those patients with mild cardiac lesions are potentially at risk for SCD. This highlights the need for further prospective studies as well as vigilant ongoing follow-up of the adult with CHD.

Novel GATA4 mutations in patients with congenital ventricular septal defects

Background

Ventricular septal defect (VSD) is the most prevalent type of congenital heart disease and is a major cause of substantial morbidity and mortality in infants. Accumulating evidence implicates genetic defects, especially in cardiac transcription factors, in the pathogenesis of VSD. However, VSD is genetically heterogeneous and the genetic determinants for VSD in most patients remain to be identified.

Material/Methods

A cohort of 230 unrelated patients with congenital VSD was included in the investigation. A total of 200 unrelated ethnically matched healthy individuals were recruited as controls. The entire coding region of GATA4, a gene encoding a zinc-finger transcription factor essential for normal cardiac morphogenesis, was sequenced initially in 230 unrelated VSD patients. The available relatives of the mutation carriers and 200 control subjects were subsequently genotyped for the presence of identified mutations.

Results

Four heterozygous missense GATA4 mutations of p.Q55R, p.G96R, p.N197S, and p.K404R were identified in 4 unrelated patients with VSD. These mutations were not detected in 200 control individuals nor described in the human SNP database. Genetic analysis of the relatives of the mutation carriers showed that in each family the mutation co-segregated with VSD.

Conclusions

These findings expand the mutation spectrum of GATA4 linked to VSD and provide new insight into the molecular etiology responsible for VSD, suggesting potential implications for the genetic diagnosis and gene-specific therapy for VSD.

Heart transplantation in adults with end-stage congenital heart disease

Residual abnormalities in cardiac structure and function predispose adults with congenital heart disease to late-onset heart failure and its complications. Evaluation of this population requires collaboration between adult congenital and heart failure specialists. In addition to assessing heart transplant eligibility, clinicians must balance the risks of premature listing against progressive heart failure and increased waiting list mortality. Following heart transplantation, adults with congenital heart disease have higher mortality due to an increased risk of bleeding, infection and donor right heart failure secondary to pulmonary hypertension. Concerns relating to increased early mortality should be balanced against superior long-term survival in adult congenital heart disease patients surviving beyond the first year after heart transplantation.

A novel GATA4 loss-of-function mutation associated with congenital ventricular septal defect

Ventricular septal defect (VSD) is the most prevalent type of congenital heart disease and a major cause for the significantly increased morbidity and mortality among infants. Aggregating evidence indicates that genetic defects are involved in the pathogenesis of congenital VSD. Nevertheless, VSD is genetically heterogeneous, and the genetic determinants for VSD in the majority of patients remain to be identified. In this study, the entire coding region of GATA4, a gene encoding a zinc finger transcription factor essential for normal cardiac morphogenesis, was sequenced in 160 unrelated patients with VSD. The available relatives of the index patient harboring the identified mutation and 200 unrelated control individuals were subsequently genotyped. The disease-causing potential of a sequence alteration was evaluated by MutationTaster, and the functional effect of the mutation was characterized using a luciferase reporter assay system. As a result, a novel heterozygous GATA4 variation, p.R43W, was identified in a proband with VSD, that was absent in control subjects. Genetic analysis of the family members of the variation carrier showed that the substitution co-segregated with VSD. The p.R43W variant was predicted to be a pathogenic mutation, and the functional analysis demonstrated that the GATA4 R43W mutant protein resulted in significantly decreased transcriptional activity compared with its wild-type counterpart. The findings expand the mutational spectrum of GATA4 linked to VSD and provide more insight into the molecular mechanism of VSD.