Maron et al. at the Minneapolis Heart Institute, USA, performed a retrospective analysis of data from 900 patients with hypertrophic cardiomyopathy (HCM) in four communities. The results showed that the prevalence of stroke and peripheral vascular embolic events was 6% in patients with HCM, with an annual incidence of 0.8%. Anticoagulation therapy appears to reduce their incidence. Stroke and arterial embolism are its complications. Yet little is known about the frequency and determinants of these important cardiovascular events, and HCM and the clinical types of these complications have never been systematically studied. This is an important clinical issue because anticoagulation therapy is effective in preventing the development of cardiogenic embolism. This study found that of 900 patients with HCM, 51 (6%) had a stroke or other vascular event in (7±7) years, and 44 of these patients had a stroke. Of these 51 patients, 21 (41%) died or were permanently disabled, with an overall annual incidence rate of 0.8% and 1.9% for patients >60 years of age. The age at first event ranged from 29 to 86 years (mean 61 ± 14 years). The majority (72%) of events occurred in patients >50 years of age, and 14 (28%) younger patients (≥50 years) also had an embolic event. Multivariate analysis showed that stroke and other peripheral vascular events were independently associated with congestive symptoms, older age, and the presence of atrial fibrillation at the first visit (45 of 51 patients, or 88%). The cumulative incidence of these events was significantly higher in patients with atrial fibrillation not treated with anticoagulation than in those on warfarin (31% versus 18%; P<0.05).