Congenital long and short QT syndromes.

Congenital long and short QT syndromes are familial arrhythmias characterized by derangement of repolarization and a high risk of sudden cardiac death due to ventricular tachyarrhythmias. With growing understanding of these syndromes in both the medical and lay communities, diagnostic and therapeutic difficulties are increasingly faced by health care providers. Modern genomics has determined the mechanism of arrhythmia induction in these patients, resulting in specific medical therapies and improved risk stratification. This paper reviews the common presentations, genetic etiology, basic evaluation, risk stratification, and therapeutic approach for both syndromes. Particular attention is paid to the effect of the individual syndrome on the cardiac action potential and its correlate the surface 12 lead ECG. In conclusion, patients with long and short QT syndromes are at risk for sudden death, with accurate diagnosis, risk stratification, and resulting appropriate therapy favorably altering their outcome.