Contemporary clinical characteristics and management patterns in hypertrophic cardiomyopathy: insights from baseline enrolment data in a nationwide prospective Japanese registry.

Background: The Japanese Hypertrophic Cardiomyopathy Registry Study was designed to provide comprehensive, real-world insights into the clinical characteristics and management of hypertrophic cardiomyopathy (HCM) in Japan.

Methods: This multicentre, prospective study enrolled consecutive patients with HCM from 24 referral hospitals across Japan starting in 2016. The baseline characteristics of 1485 patients enrolled by December 2019 are presented in this analysis.

Results: The median ages at registration and diagnosis were 69 and 60 years, respectively, with men accounting for 54% of the cohort. Familial HCM was confirmed in 18% of cases. Of the cohort, 36% had hypertrophic obstructive cardiomyopathy (HOCM), while 8% had mid-ventricular obstruction, 14% had apical HCM and 4% were in the end-stage phase. Atrial fibrillation was observed in 27% of patients, though the majority were asymptomatic or had mild symptoms at registration. Adverse outcomes included prior sustained ventricular tachycardia or fibrillation (6%), heart failure requiring hospitalisation (11%) and embolic events (5%). Defibrillator implantation was performed in 11% of patients. Differences in the defibrillator indications for primary prevention in the current three guidelines and status of defibrillator deployment at registration were clarified: the percentages of class IIa recommendation in the whole cohort and of patients with defibrillator implantation in class IIa were 22% and 19% in the Japanese guidelines, 4% and 39% in the European guidelines and 28% and 22% in the American guidelines, respectively. Beta blockers were prescribed to 90% of patients with HOCM, while 51% received cibenzoline. Septal reduction therapies were performed in 22% of patients with HOCM, with 6% undergoing surgical myectomy.

Conclusions: As the first large-scale, prospective HCM registry in Japan, this study provides valuable baseline data on the clinical characteristics and management of HCM. These findings will help address gaps between current practice and guideline recommendations, improving the care of patients with HCM.