Prognosis and prognostic factors in patients with hypertrophic cardiomyopathy in Japan: results from a nationwide study

Objective: To investigate prognosis and prognostic factors in patients with hypertrophic cardiomyopathy (HCM) in Japan. Design: A nationwide epidemiological study. Setting: Hospitals selected randomly from among all hospitals in Japan. Patients: Clinical and epidemiological information for 2155 patients with HCM were collected in 1999. Main outcome measures: Patients were classified on the basis of baseline prognostic factors. Survival rates up to 5 years were calculated by Cox’s proportional hazard model for 1605 patients. Results: During the follow-up period, 241 deaths were recorded. The crude 5-year survival rate for the entire cohort was 86% (95% CI 84 to 88), and annual mortality ranged from 2.2% to 3.0%. A higher cardiothoracic ratio on chest x ray (HR 1.61; 95% CI 1.26 to 2.05, with 1 SD (6.2%) increase), a lower left ventricular ejection fraction (HR 1.42; 95% CI 1.20 to 1.69, with 1 SD (13%) decrease) and the presence of left bundle branch block (HR 3.14; 95% CI 1.28 to 7.71) were independently associated with a poorer prognosis, whereas the presence of apical hypertrophy at baseline (HR 0.58; 95%CI 0.36 to 0.92) predicted a better chance of survival. Conclusions: The nationwide survey of patients with hypertrophic cardiomyopathy yielded important information on its prognosis and prognostic factors. These observations afford, for the first time, a measure of risk stratification in patients with HCM in Japan.