Ihor Gussak

J-Wave syndromes expert consensus conference report: Emerging concepts and gaps in knowledge

The J-wave syndromes (JWSs), consisting of the Brugada syndrome (BrS) and early repolarization syndrome (ERS), have captured the interest of the cardiology community over the past 2 decades following the identification of BrS as a new clinical entity by Pedro and Josep Brugada in 1992.[1][1] The

J-Wave syndromes expert consensus conference report: Emerging concepts and gaps in knowledge☆☆☆

J-Wave syndromes expert consensus conference report: Emerging concepts and gaps in knowledge Charles Antzelevitch, PhD, FHRS, Gan-Xin Yan, MD, PhD, Michael J. Ackerman, MD, PhD, Martin Borggrefe, MD, Domenico Corrado, MD, PhD, Jihong Guo, MD, Ihor Gussak, MD, PhD, Can Hasdemir, MD, Minoru Horie, MD, Heikki Huikuri, MD, Changsheng Ma, MD, Hiroshi Morita, MD, PhD, Gi-Byoung Nam, MD, PhD, Frederic Sacher, MD, PhD, Wataru Shimizu, MD, PhD, Sami Viskin, MD, Arthur A.M. Wilde, MD, PhD, FHRS

Short QT interval in clinical practice

The last ten years have seen a growing interest in clinical scenarios, where a short QT interval may play a role, especially because of an increased risk of sudden cardiac death in some situations. One such entity is Short QT Syndrome, which has emerged as a rare, but very malignant disease, in particular when the QT interval is very short. A short QT interval has also been noticed in some patients with other arrhythmic syndromes such as Idiopathic Ventricular Fibrillation, Brugade Syndrome and Early Repolarization Syndrome, but the role of a short QT interval in these settings is so far not known. Hypercalcemia often leads to shortening of the QT interval, but there are no data in humans to suggest an increased risk of sudden cardiac death in this setting. In addition, a shorter-than-usual QT interval has been reported in patients with Chronic Fatigue Syndrome and in response to atropine, catecholamine and Hyperthermia. When a short QT interval is encountered in daily clinical practice, these various scenarios needs to be considered, but it is still not possible to come up with clear guidelines for how to work up and risk stratify such individuals. Genetic testing is only useful in very few and the value of an electrophysiologic study, Holter monitoring or stress testing to assess QT adaptation to heart rate and T wave morphology analysis may all be helpful, but not well-established, tests in this setting.

Acquired (Drug-Induced) Long QT Syndrome

The most common cause of acquired drug-induced long QT syndrome (ADILQTS) in clinical practice is an exposure of the heart to drugs known for their potential to prolong the QT interval. It has long been recognized that most drugs that prolong the duration of the QT interval can cause fatal tachyarrhythmias. However, it took decades to sensitize medical and scientific communities, drug developers, and regulatory authorities to the serious adverse effects of numerous commercially available or investigational cardiovascular and noncardiovascular pharmaceutical agents. The most comprehensive appreciation of the magnitude of drug-induced iatrogenic death took place after the highly publicized withdrawal of the nonsedating antihistamine terfenadine and the gastrointestinal drug cisapride in the late 1990s. Numerous cases of sudden cardiac death (SCD) and life-threatening ventricular tachyarrhythmias, such as torsade de pointes (TdP)—known for its association with prolonged QT interval—inducedDrug-Induced by those drugs, were reported to the worldwide postmarketing database. As a result, a substantial number of torsadogenic drugs with “QT liability” have been withdrawn from the market over the past decade, in fact, more drugs have been withdrawn for this than for any other reason.1

History of the J Wave and J Wave Syndromes

Since discovery of the Brugada syndrome, ECG phenomena of late ventricular depolarization and early ventricular repolarization has rapidly gained recognition as a major cause of life-threatening arrhythmias, and dramatically accelerated a series of remarkably insightful discoveries in experimental, genetic, and clinical cardiac electrophysiology. Theme of “J-wave Syndromes” occupies a prominent portion of the time devoted to cardiac arrhythmias at national and international meetings, and continuing to appear in publications on the subject continue to appear at a brisk rate. More questions than answers still remain with regard to etiology, pathogenesis, arrhythmogenesis, risk stratification, epidemiology, prevention, and treatment of the JWS. These and other ambiguities concerning diagnosis and arrhythmogenic potential of the JWS have prompted an “Expert Consensus Conference on J-wave Syndromes. Mechanisms, Diagnosis, Prognosis, Risk Stratification and Treatment of Brugada and Early Repolarization Syndromes” to be held in Shanghai, China on April 21–23, 2015.

Fundamentals of ECG Interpretation in Clinical Research and Cardiac Safety Assessment

The interpretation of ECGs recorded during clinical drug trials shares many similarities with the clinical interpretation of ECGs, but also differs in several significant ways. The fundamental rules for measurement of ECG intervals and overall ECG interpretation (cardiac rhythm, conduction, etc.) are identical whether an ECG is recorded from a patient having chest pain in an emergency room, or from a healthy subject involved in a clinical drug trial. But, the overall purpose of the evaluation of two such ECGs differs greatly.