Epsilon Waves as an Extreme Form of Depolarization Delay: Focusing on the Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia

The differentiation of the competitive athlete with physiologic cardiac remodeling from the athlete with cardiomyopathy

There are currently 5 million active high school, collegiate, professional, and master athletes in the United States. Regular intense exercise by these athletes can promote structural, electrical and functional remodeling of the heart, which is termed the "athlete's heart." In addition, regular intense exercise can lead to pathological adaptions that promote or worsen cardiac disease. Many of the athletes in the United States seek medical care. Consequently, physicians must be aware of the normal cardiac anatomy and physiology of the athlete, the differentiation of the normal athlete heart from the athlete with cardiomyopathy, and the contemporary care of the athlete with a cardiomyopathy. In athletes with persistent cardiovascular symptoms, investigations should include a detailed history and physical examination, an ECG, a transthoracic echocardiogram, and in athletes in whom the diagnosis is uncertain, a maximal exercise stress test or a continuous ECG recording, and cardiac magnetic resonance imaging or cardiac computed tomography angiography when definition of the coronary anatomy or characterization of the aorta and the aortic great vessels is indicated. This article discusses the differentiation of the normal athlete with physiologic cardiac remodeling from the athlete with hypertrophic, dilated or arrhythmogenic ventricular cardiomyopathy (ACM). The ECG changes in trained athletes that are considered normal, borderline, or abnormal are listed. In addition, the normal echocardiographic measurements for athletes who consistently participate in endurance, power, combined or heterogeneous sports are enumerated and discussed. Algorithms are listed that are useful in the diagnosis of trained athletes with borderline or abnormal echocardiographic measurements suggestive of cardiomyopathies along with the major and minor criteria for the diagnosis of ACM in athletes. Thereafter, the treatment of athletes with hypertrophic, dilated, and arrhythmogenic right ventricular cardiomyopathies are reviewed. The distinction between physiologic changes and pathologic changes in the hearts of athletes has important therapeutic and prognostic implications. Failure by the physician to correctly diagnose an athlete with hypertrophic cardiomyopathy, dilated cardiomyopathy, or ACM, can lead to the sudden cardiac arrest and death of the athlete during training or sports competition. Conversely, an incorrect diagnosis by a physician of cardiac pathology in a normal athlete can lead to an unnecessary restriction of athlete training and competition with resultant significant emotional, psychological, financial, and long-term health consequences in the athlete.

Natural Course of Electrocardiographic Features in Arrhythmogenic Right Ventricular Cardiomyopathy and Their Relation to Ventricular Arrhythmic Events

BACKGROUND

Electrocardiographic abnormalities are common in arrhythmogenic right ventricular cardiomyopathy and are included in the 2010 Task Force Criteria. Their time course, however, remains uncertain. In this retrospective observational study, we aimed to assess the long-term evolution of electrocardiographic characteristics and their relation to ventricular arrhythmias.

METHODS AND RESULTS

Three hundred fifty-three patients with arrhythmogenic right ventricular cardiomyopathy as per the 2010 Task Force Criteria with 6871 automatically processed 12-lead digital ECGs were included. The relationship between the electrocardiographic parameters and the risk of ventricular arrhythmias was assessed at 10 years from the first ECG. Electrocardiographic parameters were compared between the first contact ECG, the ECG at diagnosis, and the most recent ECG. Median time between the first and the latest ECG was 6 [interquartile range, 1-14] years. Reductions of QRS voltage, R- and T-wave amplitudes between the first, diagnostic, and the latest ECGs were observed across precordial and extremity leads. Mean QRS duration increased from 96 to 102 ms (P<0.001), terminal activation duration (V1) from 47 to 52 ms (P<0.001), and QTc from 419 to 432 ms (P<0.001). T-wave inversions in leads V3 to V6 and aVF at first ECG were associated with ventricular arrhythmias (adjusted hazard ratio [HRadj][V3], 2.03 [95% CI, 1.23-3.34] and HRadj[aVF], 1.87 [95% CI, 1.13-3.08]).

CONCLUSIONS

Depolarization and repolarization parameters evolved over time in patients with arrhythmogenic right ventricular cardiomyopathy, supporting the progressive nature of arrhythmogenic right ventricular cardiomyopathy. Electrocardiographic abnormalities may be detected before diagnosis and might, although not fulfilling the 2010 Task Force Criteria, be markers of early disease. T-wave inversion in leads V3 or aVF before diagnosis was associated with ventricular arrhythmias during follow-up.

The Many Faces of Arrhythmogenic Cardiomyopathy: An Overview

Arrhythmogenic cardiomyopathy (AC) is a disease that involves electromechanical uncoupling of cardiomyocytes. This leads to characteristic histologic changes that ultimately lead to the arrhythmogenic clinical features of the disease. Initially thought to affect the right ventricle predominantly, more recent data show that it can affect both the ventricles or the left ventricle alone. Throughout the recent era, diagnostic modalities and criteria for AC have continued to evolve and our understanding of its clinical features in different age groups as well as the genotype to the phenotype correlations have improved. In this review, we set out to detail the epidemiology, etiologies, presentations, evaluation, and management of AC across the age continuum.

The pivotal role of ECG in cardiomyopathies

Cardiomyopathies are a heterogeneous group of pathologies characterized by structural and functional alterations of the heart. Recent technological advances in cardiovascular imaging offer an opportunity for deep phenotypic and etiological definition. Electrocardiogram (ECG) is the first-line diagnostic tool in the evaluation of both asymptomatic and symptomatic individuals. Some electrocardiographic signs are pathognomonic or fall within validated diagnostic criteria of individual cardiomyopathy such as the inverted T waves in right precordial leads (V1-V3) or beyond in individuals with complete pubertal development in the absence of complete right bundle branch block for the diagnosis of arrhythmogenic cardiomyopathy of the right ventricle (ARVC) or the presence of low voltages typically seen in more than 60% of patients with amyloidosis. Most other electrocardiographic findings such as the presence of depolarization changes including QRS fragmentation, the presence of epsilon wave, the presence of reduced or increased voltages as well as alterations in the repolarization phase including the negative T waves in the lateral leads, or the profound inversion of the T waves or downsloping of the ST tract are more non-specific signs which can however raise the clinical suspicion of cardiomyopathy in order to initiate a diagnostic procedure especially using imaging techniques for diagnostic confirmation. Such electrocardiographic alterations not only have a counterpart in imaging investigations such as evidence of late gadolinium enhancement on magnetic resonance imaging, but may also have an important prognostic value once a definite diagnosis has been made. In addition, the presence of electrical stimulus conduction disturbances or advanced atrioventricular blocks that can be seen especially in conditions such as cardiac amyloidosis or sarcoidosis, or the presence of left bundle branch block or posterior fascicular block in dilated or arrhythmogenic left ventricular cardiomyopathies are recognized as a possible expression of advanced pathology. Similarly, the presence of ventricular arrhythmias with typical patterns such as non-sustained or sustained ventricular tachycardia of LBBB morphology in ARVC or non-sustained or sustained ventricular tachycardia with an RBBB morphology (excluding the "fascicular pattern") in arrhythmogenic left ventricle cardiomyopathy could have a significant impact on the course of each disease. It is therefore clear that a learned and careful interpretation of ECG features can raise suspicion of the presence of a cardiomyopathy, identify diagnostic "red flags" useful for orienting the diagnosis toward specific forms, and provide useful tools for risk stratification. The purpose of this review is to emphasize the important role of the ECG in the diagnostic workup, describing the main ECG findings of different cardiomyopathies.

THE KEY-STONES OF RIGHT VENTRICULAR ARRHYTHMOGENIC CARDIOMYOPATHY-INDUCED MORPHOLOGICAL DISARRANGEMENT

Arrhythmogenic right ventricular cardiomyopathy is an urgent problem of modern cardiology. This myocardial remodeling manifests various desmosomopathies, channelopathies, and other mutations resulting in a violation of the coordinated heart work, particularly the myocardium. The incidence of this cardiomyopathy is not significant. Still, it is worth noting that athletes are at an increased risk of developing this disease, emphasizing the importance of studying this topic and its relevance from cardiologists and sports physicians. Moreover, the clinical pattern of this disease is heterogeneous. This pathology requires strengthening control and attention of medical personnel and constant improvement and optimization of diagnostic methods and treatment protocols. In this article, the pathophysiological mechanisms, molecular genetic aspects, and the dynamics of morphofunctional changes are represented in detail. Understanding the mechanisms of etiopathogenesis and the features of morphological changes observed in this cardiomyopathy and its more detailed study is fundamental in developing modern treatment methods to improve patients' quality and life expectancy.