On Predictors of Sudden Cardiac Death in Hypertrophic Cardiomyopathy*

The clinical diagnostic hallmark of hypertrophic cardiomyopathy (HCM) is unexplained cardiac hypertrophy, commonly found on an echocardiogram and in unfortunate occasions, in an autopsy. The latter is most tragic as HCM, a relatively common disease (1) often presenting with sudden cardiac death (SCD) in apparently healthy young individuals (2,3). Indeed, HCM is considered the most common cause of SCD in young competitive athletes (2). The unexpected SCD of young athletic individuals in conjunction with the results of earlier studies from major referral centers, reporting an annual mortality rate of approximately 2% to 6% (3–5), led to the impression that HCM is a relatively malignant disease. Population-based studies, however, suggested a more benign course with an annual mortality rate of approximately 1% (6–9). In the largest series comprised of 744 patients, the annual mortality rate was 1.2% of which approximately half were sudden unexpected deaths (9).