We thank Drs Ward and Saumarez for their valuable comments about our recent review of risk stratification for sudden death in hypertrophic cardiomyopathy (HCM),1 as well as the opportunity to discuss the role of pacing-induced electrocardiogram fractionation (PEFA) in this disease. Fifty years after Teare’s description of HCM, the identification of patients at high risk of sudden death remains a challenge. Important obstacles to the development of accurate prediction models are the complexity and variability of the underlying arrhythmogenic substrate. It is …