In this study, the percentage of nontraumatic sudden deaths attributed to “hypertrophic cardiomyopathy” was 6% versus 6.3% (8 of 126), which is lower than published series (2–3, 7, 9). It is possible that we underdiagnosed hypertrophic cardiomyopathy. However, this seems unlikely because this is an autopsy series in which there was a notable lack of myofibrillary disarray on pathology reports and because direct measurements of maximal wall thickness were available. Although it may be suggested that these patients were too young to develop characteristic anatomic findings of ventricular hypertrophy, recent work by Maron and colleagues (40) found that ventricular thickness was highest in the youngest age group (18 to 39 years of age) and that thickness was reduced in persons older than 40 years of age (despite increasing flow gradient). In addition, it has been shown that the risk for sudden death is highest in those with the maximal wall thickness, also making underdiagnosis less likely in this series (41). It is also possible that in previous studies of athletes who died of sudden cardiac death, echocardiographic evidence of physiologic hypertrophy from athletic training was mistaken for hypertrophic cardiomyopathy. These deaths, then, may have been due to other, possibly arrhythmogenic, causes. Of similar concern in a series of this nature is the potential for previous exclusion of persons with hypertrophic cardiomyopathy by virtue of physical examination. However, this limitation would apply to all studies of this type, including those in athletes, unless it is presumed that athletes had never undergone a physical examination.