Syncope due to Brugada syndrome in a young athlete

Recommendations for participation in leisure-time physical activity and competitive sports of patients with arrhythmias and potentially arrhythmogenic conditions. Part 2: ventricular arrhythmias, channelopathies, and implantable defibrillators

This paper belongs to a series of recommendation documents for participation in leisure-time physical activity and competitive sports by the European Association of Preventive Cardiology (EAPC). Together with an accompanying paper on supraventricular arrhythmias, this second text deals specifically with those participants in whom some form of ventricular rhythm disorder is documented, who are diagnosed with an inherited arrhythmogenic condition, and/or who have an implanted pacemaker or cardioverter defibrillator. A companion text on recommendations in athletes with supraventricular arrhythmias is published in the European Journal of Preventive Cardiology. Since both texts focus on arrhythmias, they are the result of a collaboration between EAPC and the European Heart Rhythm Association (EHRA). The documents provide a framework for evaluating eligibility to perform sports, based on three elements, i.e. the prognostic risk of the arrhythmias when performing sports, the symptomatic impact of arrhythmias while performing sports, and the potential progression of underlying structural problems as the result of sports.

The Impending Dilemma of Electrocardiogram Screening in Athletic Children

Sudden cardiac death (SCD) affects 2/100,000 young, active athletes per year of which 40% are less than 18 years old. In 2004, the International Olympic Committee accepted the Lausanne Recommendations, including a 12-lead electrocardiogram (ECG), as a pre-participation screening tool for adult Olympic athletes. The debate on extending those recommendations to the pediatric population has recently begun. The aims of our study were to highlight the characteristics of the young athlete ECG, phenotypical manifestations of SCD-related disease in children, and challenges of implanting ECG screening in athletic children. A systematic review of the literature is performed. We searched available electronic medical databases for articles relevant to SCD, ECG, silent cardiac diseases, and athletic children. We focused on ECG screening and description in a pediatric population. We identified 2240 studies. Sixty-two relevant articles and one book were selected. In children, prepubertal ECG and the ECG phenotype of most SCD-related diseases differ notably from adults. The characteristics of the prepubertal ECG and of the phenotypical manifestation of SCD-related disease in children will result in less specific and less sensitive ECG-based screening programs. Those limitations advise against extending the adult recommendation to children, without further studies. Until then, history and physical exam should remain the cornerstone of screening for SCD-related pathologies in children.

Brugada syndrome, exercise, and exercise testing

There are few data on the risk of exercise and the role of exercise stress testing in Brugada syndrome. We sought to address this deficiency using a systematic literature review. We identified 98 English-language articles possibly addressing exercise in Brugada syndrome by searching PubMed and Google Scholar from January 1990 through November 2013 using the keywords "Brugada syndrome," "exercise," "exercise testing," and "syncope" alone and in combinations. Abstracts were reviewed, and those articles pertaining to Brugada syndrome and exercise were reviewed in full. We identified 18 articles reporting on Brugada syndrome and exercise. This pool included 2 large studies of 93 and 50 Brugada subjects undergoing exercise testing, plus 16 case reports. There were no reports of exercise-related sudden death, but there were 4 cases of syncope after exercise. We identified 166 Brugada patients who underwent exercise testing. During exercise testing, there were 2 reports of ventricular tachycardia and 1 report of multiple ventricular extrasystoles. ST-segment elevation increased (ST augmentation) during the early recovery phase of exercise in 57% of patients. Exercise unmasked a Brugada electrocardiographic pattern in 5 patients. Exercise is associated with syncope and ST augmentation after exercise and may be helpful in unmasking Brugada syndrome. There are insufficient data on the risks of exercise in Brugada syndrome to make recommendations for exercise, but the observations that exercise can worsen the ST abnormalities in Brugada and produce ventricular arrhythmias suggest that patients with Brugada syndrome should be restricted from vigorous exercise.

J wave syndromes: molecular and cellular mechanisms

An early repolarization (ER) pattern in the ECG, consisting of J point elevation, distinct J wave with or without ST segment elevation or slurring of the terminal part of the QRS, was long considered a benign electrocardiographic manifestation. Experimental studies a dozen years ago suggested that an ER is not always benign, but may be associated with malignant arrhythmias. Validation of this hypothesis derives from recent case-control and population-based studies showing that an ER pattern in inferior or infero-lateral leads is associated with increased risk for life-threatening arrhythmias, termed early repolarization syndrome (ERS). Because accentuated J waves characterize both Brugada syndrome (BrS) and ERS, these syndromes have been grouped under the heading of J wave syndromes. BrS and ERS appear to share common ECG characteristics, clinical outcomes, risk factors as well as a common arrhythmic platform related to amplification of Ito-mediated J waves. However, they differ with respect to the magnitude and lead location of abnormal J waves and can be considered to represent a continuous spectrum of phenotypic expression. Recent studies support the hypothesis that BrS and ERS are caused by a preferential accentuation of the AP notch in right or left ventricular epicardium, respectively, and that this repolarization defect is accentuated by cholinergic agonists. Quinidine, cilostazol and isoproterenol exert ameliorative effects by reversing these repolarization abnormalities. Identifying subjects truly at risk is the challenge ahead. Our goal here is to review the clinical and genetic aspects as well as the cellular and molecular mechanisms underlying the J wave syndromes.

Arrhythmia and right heart disease: from genetic basis to clinical practice

Historically, left ventricular cardiomyopathy and coronary heart disease have been regarded as the main causes of ventricular arrhythmia and sudden cardiac death. However, within last two decades, arrhythmias originating from the right ventricle have begun to attract the attention of the scientific world for a number of reasons. Ventricular arrhythmias originating from the right ventricle usually affect younger patients and can lead to sudden cardiac death. The pathophysiologic mechanism of these arrhythmias is not fully understood, which can leave room for a range of different interpretations. Moreover, the intriguing world of genetics is increasingly being drawn into the pathogenesis, diagnosis and prognosis of some of these arrhythmias. This review considers the pathogenesis, diagnosis and treatment of arrhythmogenic right ventricular cardiomyopathy or dysplasia (ARVD), Brugada syndrome, right ventricular outflow tract ventricular tachycardia, and arrhythmias in the right side of the heart due to congenital heart disease. In addition, because ventricular arrhythmias associated with right ventricular heart diseases such as Brugada syndrome and ARVD can explain up to 10-30% of sudden cardiac deaths in young adults in the general population and an even greater percentage in young athletes, this article contains a brief analysis of screening tests used before participation in sports, life-style modification, and treatment options for athletes affected by these conduction disorders.

The pathophysiological mechanism underlying Brugada syndrome: depolarization versus repolarization

This Point/Counterpoint presents a scholarly debate of the mechanisms underlying the electrocardiographic and arrhythmic manifestations of Brugada syndrome (BrS), exploring in detail the available evidence in support of the repolarization vs. depolarization hypothesis.

Exercise-induced ECG changes in Brugada syndrome

BACKGROUND

Ventricular arrhythmia occurrence during exercise is reported in Brugada syndrome (BrS). Accordingly, experimental studies suggest that BrS-linked SCN5A mutations reduce sodium current more at fast heart rates. Yet, the effects of exercise on the BrS ECG phenotype have not been studied. We aimed to assess ECG responses to exercise in BrS and determine whether these responses are affected by the presence of an SCN5A mutation.

METHODS AND RESULTS

ECGs at baseline, at peak exercise, and during recovery were analyzed from 35 male control subjects, 25 BrS men without SCN5A mutation (BrS(SCN5A)(-)), and 25 BrS men with SCN5A mutation (BrS(SCN5A+); 15 with missense mutation and 10 with mutation leading to premature truncation of the protein). No differences existed in clinical phenotype between BrS groups. At baseline, BrS(SCN5A)(-) and BrS(SCN5A+) patients had lower heart rates, wider QRS, shorter QT(c), and higher peak J-point amplitudes than control subjects; BrS(SCN5A+) patients also had longer PR than BrS(SCN5A)(-) and control subjects. Exercise resulted in PR shortening in all groups, more QRS widening in BrS(SCN5A+) than in BrS(SCN5A)(-) and control subjects(,) and less QT shortening in BrS(SCN5A)(-) and BrS(SCN5A+) than in control subjects. The latter resulted in QT(c) shortening in control subjects but QT(c) prolongation in BrS(SCN5A)(-) and BrS(SCN5A+). Finally, the increase in peak J-point amplitude during exercise was similar in all 3 groups but resulted in a coved-type pattern only in BrS(SCN5A)(-) and BrS(SCN5A+).

CONCLUSIONS

Exercise aggravated the ECG phenotype in BrS. The presence of an SCN5A mutation was associated with further conduction slowing at fast heart rates. Possible mechanisms that may explain the observed ECG changes are discussed.