Syncope and cardiac arrest during strenuous exercise associated with a novel mutation in <scp>LQTS</scp> 1

Hereditary long QT syndrome (LQTS) is a genetic disorder resulting in delayed ventricular repolarization manifesting as a prolonged QT interval on the electrocardiogram and an increased propensity for polymorphic ventricular tachycardia (torsade de pointes), syncope, and sudden arrhythmic death in young adults without structural abnormalities. Originally described as Romano–Ward and Jervell and Lange‐Nielsen syndromes, breakthroughs in genetic and molecular analyses have allowed for more specific descriptions of a similar disease phenotype 1. Point mutations on five genes primarily affecting the function of the cardiac potassium current: KCNQ1 (LQTS1), KCNH2 (LQTS2), SCN5A (LQTS3), minK (LQTS5), and MiRP1 (LQTS6) have been implicated. Mutations in the KCNQ1 gene have been reported in 39–62% of patients with autosomal‐dominant LQTS where sudden cardiac death is often triggered by physical activity 2. The clinical triad of atrial fibrillation, cardiomyopathy, and sudden cardiac death in association with LQTS has not been previously described. We report a case of cardiac arrest with vigorous exercise, paroxysmal atrial fibrillation, and development of cardiomyopathy where subsequent genetic analysis identified a novel mutation in the KCNQ1 gene and LQTS1.