Arrhythmias in Adults With Congenital Heart Disease: What the Practicing Cardiologist Needs to Know

The expanding population of adults with congenital heart disease (CHD) combined with the pervasiveness of arrhythmias has resulted in the rapid growth of a dedicated sector of cardiology at the intersection between 2 subspecialties: electrophysiology and adult CHD. Herein, practical considerations are offered regarding urgent referral for catheter ablation of atrial arrhythmias, anticoagulation, and primary prevention implantable cardioverter-defibrillators (ICDs). Patients with Ebstein anomaly and ventricular pre-excitation should be referred promptly due to the high prevalence of multiple accessory pathways and increased incidence of atrial tachyarrhythmias, which may be poorly tolerated. In patients with transposition of the great arteries and atrial switch surgery, atrial arrhythmias should be managed without delay because they could provoke ventricular arrhythmias and sudden death. Other settings in which atrial arrhythmias can be poorly tolerated include single ventricle physiology and Eisenmenger syndrome. Long-term anticoagulation is generally indicated in patients with sustained intra-atrial reentrant tachycardia or atrial fibrillation and a mechanical valve, moderate or severe systemic atrioventricular valve stenosis, traditional risk factors for stroke, and/or moderate or complex CHD. The only class I indication for a primary prevention ICD is a systemic left ventricular ejection fraction ≤ 35%, with biventricular physiology, and New York Heart Association class II or III symptoms. ICD therapy is reasonable in selected adults with tetralogy of Fallot and multiple risk factors for sudden death identified by observational studies. Indications for ICDs in patients with systemic right ventricles and univentricular hearts are less well established, underscoring the need for future research to inform risk stratification.     

Prevalence and incidence of arrhythmias and sudden death in heart failure

Patients with heart failure are prone to a variety of arrhythmias, symptomatic and asymptomatic, that are prognostically significant and have an important bearing on the management of these patients. However there are some inherent problems in assessing the frequency of these arrhythmias within a large patient population, due to a lack of uniformity in defining heart failure and the transient nature of these rhythms. Patients with heart failure commonly die suddenly. The causes of these deaths are difficult to ascertain accurately and are often presumed arrhythmic. With the advent of effective interventions to prevent sudden death, accurately defining the causal relationship between the arrhythmias and sudden death has assumed great importance to appropriately target therapy. Several attempts have been made to predict such deaths on the basis of non-invasive and invasive diagnostic investigations with variable success. In this article we review the incidence and prevalence of atrial and ventricular arrhythmias and sudden deaths in epidemiological studies, surveys and randomised control trials of patients with heart failure. We discuss the prognostic significance of these arrhythmias, the inherent problems in their diagnosis and whether their presence predicts the risk of sudden deaths and the mode of such deaths in the heart failure population. The role of various investigations in risk stratification of sudden death has also been discussed     

Arrhythmias in Patients with Heart Failure

Opinion statement Both atrial and ventricular arrhythmias are very common in patients with congestive heart failure, and their presence is associated with symptoms, significant morbidity, and mortality. Studies have attempted to determine the prognostic significance of atrial and ventricular arrhythmias in patients with heart failure. Whether atrial fibrillation is an independent risk factor of mortality remains controversial. The presence of ventricular arrhythmias in patients with ischemic cardiomyopathy identifies patients at high risk for sudden death. However, in patients with nonischemic cardiomyopathy there is not a strong correlation between ventricular arrhythmias and increased risk for sudden death. Multiple trials using antiarrhythmic drugs, pharmacologic therapy, and implantable cardioverter defibrillators have been performed in an attempt to improve survival in patients 1) post-myocardial infarction; 2) with congestive heart failure, with and without nonsustained ventricular tachycardia; and 3) with sustained ventricular tachycardia and those who have survived an out-of-hospital cardiac arrest. The purpose of this article is to present an overview of arrhythmias in patients with heart failure and discuss the prevalence, prognostic significance, complications, mechanisms, and trials that have formed the current therapies presently used.     

Cardiovascular Risk Factors in Patients With Congenital Heart Disease

Survival of infants born with congenital heart disease (CHD) is improving tremendously and although most of them have mild lesions, others might be considered as only being palliated and undergo many medical or surgical interventions. Patients with CHD will be exposed to the same problematic of the modern lifestyle such as increased prevalence of obesity, decreased physical activities, and exposure to smoking, which leads to acquired cardiovascular disease. We specifically investigated specific cardiovascular risk factors such as: malnutrition, smoking exposure, hypertension, integrity of the coronary and systemic arteries, thromboembolism, ventricular dysfunction, inflammation, and arrhythmias. Patients with CHD are often submitted to extremes of nutrition: as infants, they often do not meet their metabolic requirements, and as they grow older, they tend to exceed them, as seen in the general population. Some heart lesions are more prone to systemic hypertension throughout life, such as coarctation of the aorta, but surprisingly other lesions are also prone to hypertension such as Ebstein anomaly, pulmonary valve stenosis, or regurgitation. Early coronary artery atherosclerosis is also a concern in these patients. Lesions typically at risk are localized in zones of increased turbulence or high pressure or having had previous surgical manipulations. Thromboembolism is also frequent and mostly associated with arrhythmias, heart failure, multiple catheterizations, and specific surgical repairs. Finally, the complexity of heart lesions or abnormal hemodynamics lead to inflammation, heart failure, or arrhythmias. These complex interactions of risk factors ultimately lead to a decreased life expectancy.     

Burden of Heart Failure in Adults with Congenital Heart Disease

Patients born with congenital heart disease (CHD) have benefited from remarkable advances in surgical and catheter-based interventions. As a result, the majority of children born with even the most complex forms of CHD live into adulthood. The specialized field of adult CHD (ACHD) was born out of the necessity to care for this new population of survivors of childhood CHD and their distinctive features. In this review, relevant aspects of ACHD that lead to, and are affected by, heart failure will be examined along with the increasing prevalence of HF in the burgeoning population of ACHD. We also highlight the challenges in defining HF in this particular group of patients.     

Predicting Sudden Cardiac Death in Genetic Heart Disease

Genetic heart diseases are common causes of sudden cardiac death (SCD) in the young and are typically divided into inherited cardiomyopathies and primary electrical heart diseases. Cardiomyopathies associated with risk of SCD include hypertrophic cardiomyopathy (HCM) and arrhythmogenic cardiomyopathy (ACM). The latter includes arrhythmogenic right ventricular cardiomyopathy (ARVC) as well as ACM primarily affecting the left ventricle, such as lamin cardiomyopathy. Primary electrical diseases more commonly seen in clinical practice include Brugada syndrome (BrS) and long QT syndrome (LQTS). Risk stratification of SCD is a central component of the management of patients with these genetic heart diseases. Numerous risk factors have been identified with variable degrees of scientific evidence. More recently, risk prediction models have been developed to estimate the absolute risk of sustained arrhythmias and SCD, to support clinicians and patients in decision making regarding prophylactic implantable cardioverter-defibrillators (ICDs). This paper provides a practical review of the current literature on risk stratification in ARVC and other ACMs, HCM, BrS, and LQTS, and summarises current recommendations for ICD use.     

Hazards,Risks, and Threats of Heart Disease from the Early Stages to Symptomatic Coronary Heart Disease and Cardiac Failure

The epidemiologic approach to investigation of atherosclerotic cardiovascular disease has provided many insights into the preclinical and clinical spectrum of the disease. The hazard of developing atherosclerotic cardiovascular disease is substantial with coronary heart disease (CHD), the most common and most lethal feature. The outlook in those who manage to survive the initial episode is also serious, with a 10-year mortality rate of 37% for persons with angina and a 55% rate for those sustaining a myocordial infarction (M). Fifteen percent of persons developing CHD present with a fatal event, and 38% of infarctions go unrecognized. The presence of atherosclerosis in one vascular territory imposes an increased risk of its appearing in another area at two to six times the general population rate. The major cardiovascular risk factors adversely affect all arterial vascular territories so that correction of risk factors targeted at one particular atherosclerotic outcome may also favorably influence the other risk factors. Coronary disease is the most prevalent lethal hazard of hypertension, dyslipidemia, glucose intolerance, and cigarette smoking. These risk factors cluster and optimal therapy must improve the whole risk profile. Women share the same risk factors for CHD as men. Although women have a lower absolute risk for most risk factors, a high total/HDL cholesterol ratio, left ventricular hypertrophy, and diabetes each tend to eliminate the female advantage. Menopause also promptly escalates risk threefold. Although women tend to have a lower incidence than men, the initial attack is just as highly lethal in women, and their subsequent outlook as survivors is at least as serious as for men. Sudden death is a pre-eminent feature of coronary disease and cardiac failure. Coronary disease increases sudden death risk 3.3-fold and cardiac failure 4.8-fold. Sudden death incidence varies in relation to the same cardiovascular risk factors as coronary heart disease, with no unique risk factors identified. However, multivariate combinations of these in a profile can identify high-risk candidates for sudden death as well as coronary attacks in general. The key to prevention of sudden death is to prevent coronary attacks and cardiac failure.Despite aggressive cardiac revascularization and treatment of hypertension, congestive heart failure (CHF) has not decreased in prevalence, and innovations in the treatments of overt failure have not substantially improved survival. Median survival is only 1.7 years for men and 3.2 years for women. The conditional probability of developing CHF can be estimated using a logistic function comprised of age, systolic pressure, vital capacity, heart rate, ECG-left ventricular hypertrophy (LVH), glucose intolerance, x-ray enlargement, and presence of CHD and heart murmurs. Eight percent of CHF events occur in persons in the upper quintile of multivariate risk. Continued clinical, metabolic, and epidemiologic research have expanded and refined atherosclerosis risk factors. The lipid connection is now concerned with the apoprotein makeup of the lipids, subfractions of lipids, and Lp(a). The diabetic influence is now focused on insulin resistance. Ambulatory monitoring is being used to evaluate blood pressure and silent ischemia. Fibrinogen and leukocyte counts have emerged as possible indicators of unstable lesions.Prospects for primary and secondary prevention are good if public health measures, health education, and preventive medicine are implemented based on existing knowledge of correctable or avoidable risk factors. The potential for more effective prevention continues to expand, and great advances have already been made in countries where aggressive preventive measures have been implemented to correct the major established risk factors.     

What causes sudden death in heart failure?

Patients with heart failure experience a number of changes in the electrical function of the heart that predispose to potentially lethal cardiac arrhythmias. Action potential prolongation, the result of functional downregulation of K currents, and aberrant Ca2+ handling is a recurrent theme. Significant alterations in conduction and activation of a number of initially adaptive but ultimately maladaptive signaling cascades contribute to the generation of a highly arrhythmogenic substrate. We review the changes in active and passive membrane properties, neurohumoral signaling, and genetic determinants that predispose to sudden arrhythmic death in patients with heart failure and highlight the critical unanswered questions that are ripe for future investigation.     

Risk Stratification and Prevention of Sudden Death in Patients with Heart Failure

For almost the past decade, recommendations for the use of implantable cardioverter defibrillators (ICDs) for primary prevention of sudden cardiac death have been based upon the left ventricular ejection fraction (LVEF). Current guidelines recommend an ICD for heart failure patients with LVEF ≤35% and NYHA functional class of II or III; however, because the majority of heart failure patients who qualify for ICD implantation based on these criteria will never have an event requiring ICD therapy over several years of follow-up, additional methods of risk stratification for sudden death are clearly needed. Additionally, most of the nearly 300,000 cardiac arrests that occur each year occur in patients without heart failure or significant left ventricular dysfunction. To improve the identification of patients at risk for sudden death, several criteria other than ejection fraction have been proposed and studied. Markers of autonomic tone, including heart rate turbulence and QT dynamicity, have shown some ability to predict total mortality but not arrhythmic events. Microvolt T-wave alternans testing was initially thought to be highly predictive of life-threatening arrhythmias, but prospective large sub-studies of the MADIT II and SCD-HeFT trials have failed to show a predictive value for T-wave alternans testing. Newer markers for risk are based upon the detection of myocardial fibrosis, which forms the substrate for re-entrant and malignant ventricular tachyarrhythmias. Markers of collagen turnover or quantification of myocardial scar by MRI may hold the best promise for identifying patients at highest risk for sudden cardiac death and may also identify patients at high risk but with an ejection fraction above 35%, who are not currently recommended for ICD implantation.     

心力衰竭与心律失常

心力衰竭与心律失常可互为因果,相互共存,心律失常加重心力衰竭病情并影响预后。药物治疗心力衰竭伴心律失常应针对病因,减轻症状,减少死亡率。非药物治疗对部分心力衰竭伴心房颤动有效,植入式心律转复除颤器可降低心力衰竭猝死发生率,可用于心力衰竭猝死的一级预防和二级预防。     

Prognostic evaluation of patients surviving acute myocardial infarct: univariate and multivariate analysis

The relationship between 31 variables and survival after acute myocardial infarction was evaluated in 432 patients discharged from our Coronary Care Unit from 1975 to 1984. The patients were followed for 1 to 105 months and either univariate and multivariate analysis were performed. For end-point death the significant variables (p less than 0.05) selected by the univariate analysis were: age, diabetes, smoke, heart rate at recovery, supraventricular arrhythmias, cardiac failure and complex ventricular arrhythmias either during recovery, either after discharge and finally spontaneous angina after hospital discharge. Meanwhile, for the end-point cardiac death age, smoke and supraventricular arrhythmias were not yet significant while arterial pressure at recovery and effort angina after hospital discharge were. Multivariate analysis identified cardiac failure during recovery, diabetes, complex ventricular arrhythmias before and spontaneous angina after discharge as independent variables contributing to total mortality: effort angina was a further significant one relatively to cardiac death. Thus, our study points out the importance of multivariate survival analysis when evaluating the relationship between survival after discharge for the effect of other prognostic factors. Moreover, providing identification of high risk cohorts permits appropriate interventions designed to lessen risk.     

Treatment of Ventricular Tachycardia in Patients with Heart Failure

Heart failure is a major public health concern that is frequently complicated by ventricular arrhythmias. Sustained ventricular tachycardia is associated with an increased risk for progressive heart failure and sudden death. We summarize the current management strategies for ventricular tachycardia in heart failure patients, including implantable cardioverter-defibrillator therapy, pharmacologic therapy, catheter ablation techniques, ventricular assist device therapy, and heart transplantation.     

The Failing Right Ventricle in Congenital Heart Disease

In congenital heart disease (CHD) the right ventricle (RV) dons a variety of hats. It might be situated in the normal subpulmonary position and function as half of a 2-pump circulation, but nonetheless be subjected to abnormal loading conditions, surgical interventions, or electrical disturbance. Alternatively, it can be required to generate systemic cardiac output; either in the context of a univentricular circulation or else in concert with a subpulmonary left ventricle. Each role carries different hemodynamic stresses and physiologic demands and the long-term capacity of the RV to withstand the stresses and meet those demands has become recognized as a key contributor to late clinical outcomes. RV failure in CHD usually has an etiology and pathophysiology quite different from RV failure in other circumstances and there is little evidence to support direct transition of treatments well established in acquired heart failure in this patient group. In this review we discuss the requirements for normal RV function, situations in CHD in which the RV is prone to failure, the pathophysiology of RV dysfunction, and potential therapeutic options.     

扩张型心肌病临床与预后的关系探讨

目的 :探讨扩张型心肌病(DCM )发生心脏性猝死 (SCD)的高危因素 ,研究DCM临床与预后的关系。方法 :对 60例DCM临床资料进行分析 ,以超声心动图 (UCG)、心电图 (ECG)、动态心电图 (DCG、Holter)及X线胸片观察心脏各参数变化 ,并做心电图QT离散度 (QTd)测定。结果 :有病毒性心肌炎病史与无病毒性心肌炎病史病人 ,重度心力衰竭、严重室性心律失常的发生率分别为 66.7%和 2 3 .3 % ,经比较有统计学意义 (P <0 .0 5 ) ;5例SCD均有病毒性心肌炎史 ,临死前都发生多次严重室性心律失常、晕厥 ;QTd对预测SCD高危因素有意义。结论 :有病毒性心肌炎史、心力衰竭、严重室性心律失常、头晕或晕厥及QTd增加 ,可作为预测发生SCD的高危因素。     

Identifying high risk in adults with congenital heart disease and atrial arrhythmias

Atrial arrhythmias are associated with an increased mortality risk in adults with congenital heart disease (CHD). However, little is known about risk stratification in the specific group of adult patients with CHD and atrial arrhythmias. We sought to identify predictors of mortality in adult with CHD and atrial arrhythmias and to establish a risk score. The study involved 378 adult patients with CHD (mean age 39 ± 13 years) and atrial arrhythmias who had serial follow-up in a tertiary referral center from 1999 through 2009. During a median follow-up of 5.2 years, there were 40 deaths (11%). Overall mortality rate was 2.0% per patient-year. Common modes of death included heart failure-related death (35%), sudden cardiac death (20%), and perioperative death (18%). Independent predictors of mortality were poor functional class (hazard ratio 3.69, 95% confidence interval [CI] 1.69 to 8.03, p = 0.001), single-ventricle physiology (hazard ratio 3.33, 95% CI 1.51 to 7.35, p = 0.003), pulmonary hypertension (hazard ratio 2.96, 95% CI 1.41 to 6.19, p = 0.004), and valvular heart disease (hazard ratio 2.73, 95% CI 1.33 to 5.59, p = 0.006). A risk score was constructed using these predictors in which patients were assigned 1 point for the presence of each risk factor. Mortality rates in the low-risk (no risk factor), moderate-risk (1 risk factor), and high-risk (>1 risk factor) groups were 0.5%, 1.9%, and 6.5% per patient-year, respectively (log-rank p <0.001). In conclusion, in adult with CHD and atrial arrhythmias specific clinical variables identify patients at high risk for death. Importantly, the absence of any of these risk factors is associated with an excellent survival despite the presence of atrial arrhythmias.     

Cardiac damage in athlete's heart: When the “supernormal” heart fails!

Intense exercise may cause heart remodeling to compensate increases in blood pressure or volume by increasing muscle mass. Cardiac changes do not involve only the left ventricle, but all heart chambers. Physiological cardiac modeling in athletes is associated with normal or enhanced cardiac function, but recent studies have documented decrements in left ventricular function during intense exercise and the release of cardiac markers of necrosis in athlete's blood of uncertain significance. Furthermore, cardiac remodeling may predispose athletes to heart disease and result in electrical remodeling, responsible for arrhythmias. Athlete's heart is a physiological condition and does not require a specific treatment. In some conditions, it is important to differentiate the physiological adaptations from pathological conditions, such as hypertrophic cardiomyopathy, arrhythmogenic dysplasia of the right ventricle, and non-compaction myocardium, for the greater risk of sudden cardiac death of these conditions. Moreover, some drugs and performance-enhancing drugs can cause structural alterations and arrhythmias, therefore, their use should be excluded.     

New Paradigms in the Prevention of Sudden Cardiac Arrest and Heart Failure Treatment

Congestive heart failure is a very real public health issue not only in the United States, but worldwide. Mortality in patients with congestive heart failure is typically either sudden cardiac death or pump failure. Paradoxically, patients with less severe heart failure are at higher relative risk of sudden cardiac death. Defining which patients are best treated with implantable defibrillators and resynchronization is the purpose of this review.     

Ventricular arrhythmias in heart failure.

Heart failure is an increasingly common disorder leading to reduced quality and expectancy of life. Asymptomatic and symptomatic ventricular arrhythmias are a frequent complication and have been found to be independent prognostic predictors for sudden cardiac death in patients with heart failure. Unfortunately, the positive predictive failure for this finding is low, but in patients with sustained ventricular arrhythmias, variables indicating impaired pump function are the most important predictors of sudden and of nonsudden cardiac death. Arrhythmias in heart failure may have many different underlying mechanisms. Indications for, and mode of treatment of, arrhythmias in heart failure depend on the symptoms and prognostic significance of the arrhythmia. Primarily, pump function should be optimized and antiarrhythmic drug therapy instituted only when the arrhythmia persists. In poorly tolerated and life-threatening arrhythmias, implantable devices allowing pacing and defibrillation must be considered. No data are presently available indicating a protective role of antiarrhythmic drugs in the prevention of sudden cardiac death in heart failure. Future directions should concentrate on the development of better stratification of risk for sudden death, better delineation of mechanisms of arrhythmias in heart failure (allowing the development of mechanism-specific antiarrhythmic drugs), and research into new nonpharmacologic techniques such as cardiomyoplasty and molecular biologic techniques to rebuild the failing heart muscles.     

Atlas-Based Computational Analysis of Heart Shape and Function in Congenital Heart Disease

Approximately 1% of all babies are born with some form of congenital heart defect. Many serious forms of CHD can now be surgically corrected after birth, which has led to improved survival into adulthood. However, many patients require serial monitoring to evaluate progression of heart failure and determine timing of interventions. Accurate multidimensional quantification of regional heart shape and function is required for characterizing these patients. A computational atlas of single ventricle and biventricular heart shape and function enables quantification of remodeling in terms of z scores in relation to specific reference populations. Progression of disease can then be monitored effectively by longitudinal evaluation of z scores. A biomechanical analysis of cardiac function in relation to population variation enables investigation of the underlying mechanisms for developing pathology. Here, we summarize recent progress in this field, with examples in single ventricle and biventricular congenital pathologies.     

Chagas heart disease: An overview of diagnosis,manifestations, treatment,and care

Chagas heart disease (CHD) affects approximately 30% of patients chronically infected with the protozoa Trypanosoma cruzi. CHD is classified into four stages of increasing severity according to electrocardiographic, echocardiographic, and clinical criteria. CHD presents with a myriad of clinical manifestations, but its main complications are sudden cardiac death, heart failure, and stroke. Importantly, CHD has a higher incidence of sudden cardiac death and stroke than most other cardiopathies, and patients with CHD complicated by heart failure have a higher mortality than patients with heart failure caused by other etiologies. Among patients with CHD, approximately 90% of deaths can be attributed to complications of Chagas disease. Sudden cardiac death is the most common cause of death (55%–60%), followed by heart failure (25%–30%) and stroke (10%–15%). The high morbimortality and the unique characteristics of CHD demand an individualized approach according to the stage of the disease and associated complications the patient presents with. Therefore, the management of CHD is challenging, and in this review, we present the most updated available data to help clinicians and cardiologists in the care of these patients. We describe the clinical manifestations, diagnosis and classification criteria, risk stratification, and approach to the different clinical aspects of CHD using diagnostic tools and pharmacological and non-pharmacological treatments.