Response by Weissler-Snir and Dorian to Letter Regarding Article, "Hypertrophic Cardiomyopathy-Related Sudden Cardiac Death in Young People in Ontario".

We appreciate the comments by Dr Madias regarding the study on the incidence of hypertrophic cardiomyopathy (HCM)-related sudden cardiac death in young individuals in Ontario.[1] We entirely agree with Dr Madias that the ECG adds valuable information in HCM and may evolve with disease progression, as previously described.[2] Furthermore, gene carriers without evidence of hypertrophy on echocardiogram and cardiac magnetic resonance can display an abnormal ECG.[3] We agree it would have been interesting to see whether the ECGs of the patients who exhibited no or only mild hypertrophy but had histologic findings consistent with HCM were abnormal and could have been clinically useful for screening before the development of hypertrophy on echocardiogram. In 30 of the 50 individuals who had an autopsy, there was asymmetric septal hypertrophy; in the remaining, the hypertrophy was concentric. Electrocardiogram in apical hypertrophic cardiomyopathy with a speculation as to the mechanism of its features. [Extracted from the article]