Primary electrical disorders and arrhythmogenic right ventricular cardiomyopathy: new research insights with clinical implications

Primary electrical disorders of the heart, the so-called channelopathies, are genetically determined diseases that predispose to sudden cardiac death caused by ventricular tachyarrhythmias. They account for a considerable number of sudden death cases and their impact is catastrophic because they affect mostly young individuals. They include entities that have been first described many decades ago such as the long-QT syndrome and others that have been detected more recently such as the Brugada syndrome and the short-QT syndrome. Due to the seminal work performed in the last decades by several research groups,1–3 our pathophysiological understanding of these syndromes as well as our knowledge regarding the accompanying risk has hugely increased. In parallel, the field of sudden cardiac death prevention has undergone enormous changes with the advent of the implantable cardioverter-defibrillator.4,5 Despite these advances, both the diagnosis of the disease as well as the choice of appropriate treatment remain challenging in several cases. A further disease entity that is characterized by a significantly increased risk of sudden cardiac death and affects young individuals is the arrhythmogenic right ventricular cardiomyopathy (ARVC). The present issue of EP Europace is dedicated to manuscripts presenting research findings concerning these disease entities.6,–22 In the field of the Brugada syndrome, Letsas et al.12 report data on the value of unipolar voltage mapping in the right ventricular outflow tract for diagnosis of the syndrome. For stratification of the risk for sudden cardiac death in the syndrome and the decision on defibrillator implantation, new data are reported by Pablo et al. on the information that is provided by syncope in patients with false-negative response to provocative testing.13 Reassuringly, the overall sudden cardiac death risk of patients with Brugada syndrome seems to be relatively low as demonstrated by Delise et al.15 in a meta-analysis of several large prospective studies with a total of 1568 patients who had not received a defibrillator for primary prevention. Further reassuring data are reported by Kamakura et al.14 suggesting that beta blockers and calcium antagonists may be indeed used in selected patients with Brugada syndrome under careful observation. In the field of long-QT syndrome, Filippini et al.19 elaborate on the cut-off values for the brisk-standing-test depending on age. Alarming are the results of the observational study by Gibbs et al. who identified over a long period of 11 years a large number of 1531 patients with a QTc ≥ 500 ms. This was associated with a high all-cause mortality and, importantly, only a minority was acknowledged in the medical records.18 In the field of ARVC, Marcinkevics et al.7 investigated the diagnostic value of high-density body surface electrcardiogram mapping taking into account the positioning of the leads in non-standard locations. The challenges of risk stratification in ARVC, the change of this risk over the years and the need for systematic periodical reassessment of risk are demonstrated in the analysis of data from the Trieste Heart Muscle Disease registry by Cappelletto et al.8 Denis et al.9 compared the ventricular arrhythmogenic response to isoproterenol testing with exercise testing in newly diagnosed ARVC patients suggesting its potential utility. Finally, the issue contains further papers reporting novel findings in the field of short-QT syndrome, early repolarization pattern and autonomic risk stratification after myocardial infarction. In summary, research keeps providing important new findings that broaden our understanding of these diseases and may lead to an improved management of our patients that are affected. We sincerely hope that you enjoy reading this Focused Issue of the Journal and that the science presented will be helpful to you to improve diagnosis and treatment of patients with channelopathies and related disorders. Conflict of interest: G.H. is Editor-in-Chief of EP Europace. He reports research grants from Abbott, Biotronik, Boston Scientific, and Medtronic to the Heart Center Leipzig (no personal fees).