Temporal and Global Trends of the Incidence of Sudden Cardiac Death in Hypertrophic Cardiomyopathy

Background: Since the initial clinical description of hypertrophic cardiomyopathy (HCM) over 60 years ago, sudden cardiac death (SCD) has been the most visible and feared complication of HCM. Objectives: This study sought to characterize the temporal, geographic, and age-related trends of reported SCD rates in adult HCM patients. Methods: Electronic databases were systematically searched up to November 2021 for studies reporting on SCD event rates in HCM patients. Patients with SCD equivalents (appropriate implantable cardioverter-defibrillator [ICD] shocks and nonfatal cardiac arrests) were not included. A random-effects model was used to pool study estimates calculating the overall incidence rates (IR) for each time-era, geographic region, and age group. We analyzed 2 periods (before vs after 2000, following clinical implementation of ICD in HCM). Following 2000, 5-year intervals were used to demonstrate the temporal change in SCD rates. Results: A total of 98 studies (N = 70,510 patients and 431,407 patient-years) met our inclusion criteria. The overall rate of HCM SCD was 0.43%/y (95% CI: 0.37-0.50%/y; I² = 75%; SCD events: 1,938; person-years of follow-up: 408,715), with young patients (<18 years of age) demonstrating a >2-fold-risk for sudden death vs adult patients 18-60 years of age (IR: 1.09%; 95% CI: 0.69%-1.73% vs IR: 0.43%; 95% CI: 0.37%-0.50%) (P value for subgroup differences <0.01). Contemporary SCD rates from 2015 to present were 0.32%/y and significantly lower compared with 2000 or earlier (IR: 0.32%; 95% CI: 0.20%-0.52% vs IR: 0.73%; 95% CI: 0.53%-1.02%, respectively). Reported SCD rates for HCM were lowest in North America (IR: 0.28%; 95% CI: 0.18%-0.43%,) and highest in Asia (IR: 0.67%; 95% CI: 0.54%-0.84%). Conclusions: Contemporary HCM-related SCD rates are low (0.32%/y) representing a 2-fold decrease compared with prior treatment eras. Young HCM patients are at the highest risk. The maturation of SCD risk stratification strategies and the application of primary prevention ICD to HCM are likely responsible for the notable decline over time in SCD events. In addition, worldwide geographic disparities in SCD rates were evident, underscoring the need to increase access to SCD prevention treatment for all HCM patients.