In a regionally selected patient population most closely resembling the true disease state, HCM did not significantly increase the risk of premature death or adversely affect overall life expectancy. Prevailing misconceptions of HCM as a generally unfavorable condition may largely be related to the skewed patient referral patterns characteristic of tertiary care centers. Hypertrophic cardiomyopathy is nevertheless a highly complex disease capable of serious clinical consequences and premature death in some patients.

Stroke and peripheral embolizations showed a 6% prevalence rate and an incidence of 0.8%/year in a large, unselected HCM group. These profound complications of HCM, which may lead to disability and death, were substantially more common in the elderly, occurred almost exclusively in patients with paroxysmal or chronic atrial fibrillation and appeared to be reduced in frequency by anticoagulation.

The risk of sudden cardiac death in a population of high school student athletes was small, in the range of one in 200,000 per year, and was higher in male athletes. The rare occurrence of sudden cardiac death in competitive sports underlines the limitations implicit in structuring productive and cost-effective broad-based preparticipation screening strategies for high school athletes.

Background-Death resulting from hypertrophic cardiomyopathy (HCM), particularly when sudden, has been reported to be largely confined to young persons. These data emanated from tertiary HCM centers with highly selected referral patterns skewed toward high-risk patients. Methods and Results-The present analysis was undertaken in an international population of 744 consecutively enrolled and largely unselected patients more representative of the overall HCM spectrum. HCM-related death occurred in 86 patients (12%) over 8Ϯ7 years (meanϮSD). Three distinctive modes of death were as follows: (1) sudden and unexpected (51%; age, 45Ϯ20 years); (2) progressive heart failure (36%; age, 56Ϯ19 years); and (3) HCM-related stroke associated with atrial fibrillation (13%; age, 73Ϯ14 years). Sudden death was most common in young patients, whereas heart failure-and stroke-related deaths occurred more frequently in midlife and beyond. However, neither sudden nor heart failure-related death showed a statistically significant, disproportionate age distribution (Pϭ0.06 and 0.5, respectively). Stroke-related deaths did occur disproportionately in older patients (Pϭ0.002). Of the 45 patients who died suddenly, most (71%) had no or mild symptoms, and 7 (16%) participated in moderate to severe physical activities at the time of death. Conclusions-HCM-related cardiovascular death occurred suddenly, or as a result of heart failure or stroke, largely during different phases of life in a prospectively assembled, regionally based, and predominantly unselected patient cohort. Although most sudden deaths occurred in adolescents and young adults, such catastrophes were not confined to patients of these ages and extended to later phases of life. This revised clinical profile suggests that generally held epidemiological tenants for HCM have been influenced considerably by skewed reporting from highly selected populations. These data are likely to importantly affect risk stratification and treatment strategies importantly for the prevention of sudden death in HCM. (Circulation. 2000;102:858-864.)

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