A Multi-Center Observational Study of Dilated Phase of Hypertrophic Cardiomyopathy

Introduction: Clinical features of dilated phase of hypertrophic cardiomyopathy (dHCM) have not been fully elucidated. Purpose: The purpose of this study was to reveal clinical characteristics, treatment, and prognosis in Japanese patients with dHCM. Methods and Results: Forty six dHCM patients (59.2 ± 15.6 years old, male 61%) were registered at multiple centers in Japan from April 2015 to June 2017. The interval from the onset of symptoms to the first diagnosis of HCM was 5.8 ± 8.0 years, and from HCM to the transition to dHCM was 11.7 ± 7.9 years thereafter. At the time of detection of HCM, the transition to dHCM, and the registration, left ventricular (LV) diastolic diameter, was 45.3 ± 9.8, 54.4 ± 6.5, and 56.4 ± 8.0 mm, respectively. LV ejection fraction (EF) was 70.1 ± 13.9, 44.8 ± 8.1, and 36.3 ± 9.5%, and the thickness of intraventricular septum was 21.0 ± 7.3, 14.8 ± 4.4, and 12.3 ± 3.7 mm. At registration, New York Heart Association functional class III or IV was 35%. dHCM patients were treated with renin-angiotensin system inhibitors in 82%, b-blocker in 96%, loop diuretics in 62%, and amiodarone in 38%. Twenty nine patients (63%) had prior heart failure hospitalization (HF). Patients with prior HF hospitalization were more likely to have a history of atrial fibrillation and showed lower LVEF compared with those without it. Conclusions: HCM slowly develops into dHCM over about 10 years. dHCM patients have a high rate of heart failure hospitalization.