David J. Callans, MD, reviews the arrhythmic complications of hypertrophic cardiomyopathy(HCM) and their implications for sudden cardiac death (SCD). A genetically heterogeneous heart muscle disorder, HCM occurs as an unexplained increase in wall thickness in a non-dilated chamber. Atrial fibrillation has a prevalence of 25% in younger patients with HCM, and is a risk factor for thromboembolic events. SCD is the most feared outcome in HCM, in part because it occurs in asymptomatic young adults. In this video, Dr. Callans examines these issues and concerns, discusses risk stratification and risk reduction in HCM and offers an overview of ICD therapy and VT ablation as treatments for the condition. Dr. Callans is the Associate Director of the Electrophysiology Program at Penn Medicine.