Genetic and molecular basis of cardiac arrhythmias Impact on clinical management

Clinical cardiologists who manage arrhythmias are increasingly faced with new complexities in management decisions. The once obscure science and jargon of medical genetics is assuming a much more prominent position in the mainstream medical literature, with seemingly weekly reports of new mutations to explain what once seemed very obscure diseases. This rapidly expanding knowledge base places the clinician — who usually trained when the concepts were not a major component of the medical school or fellowship training curricula — at a disadvantage in making day-to-day decisions with respect to managing common symptoms, such as unexplained syncope or heart failure. Even entertaining a diagnosis such as the congenital long QT syndrome or hypertrophic cardiomyopathy used to be a medical curiosity. Now, with increased public and physician awareness of these and even more esoteric conditions, the questions on patient management have become more common, and more complex. They include not only broad questions like ‘How can I establish (or better yet, rule out) a diagnosis?’ but also more specific issues such as ‘Should this patient undergo genetic testing? Where? How? And how can I interpret the results?’ The first and second parts of this article attempt to answer these questions. They neither teach molecular genetics nor do they provide an exhaustive review of the current state-of-the-art of molecular and genetic cardi-