Global and national insights into the decline of hypertrophic cardiomyopathy as a cause of sudden death in the young

Abstract Background & Objective Hypertrophic cardiomyopathy (HCM) has been reported as a leading cause of sudden cardiac death (SCD) in the young but appears less common in contemporary cohorts of young SCD. This research aimed to determine if HCM is a common cause of SCD in the young and whether this has changed over time. Methods We analysed three national databases, the National Echo Database Australia (NEDA), Centre for Disease Control Wide-ranging Online Data for Epidemiologic Research (CDC-WONDER) and the National Coronial Information System of Australia (NCIS) to determine incidence of SCD due to HCM in ≤ 35 years old from 1999-2017. Sub-analyses assessed for differences in sex and obstructive and non-obstructive HCM phenotypes. Results NEDA: Of 40,738 individual echocardiograms 2005-2017, 868 (2.13%) exhibited the HCM phenotype. 982 patients died ≤ 35 years, of which 4 deaths were attributable to HCM (0.4%). CDC-WONDER: 41% reduction in HCM related mortality/million people across 1999-2016 (p<.0001). Similar reduction was seen when stratified for age, sex and non-obstructive/obstructive HCM phenotype. NCIS: 36% reduction in HCM-related SCD was observed between 2001-2010 and 2011-2016 periods (p=.049). Conclusions HCM rarely causes SCD and accounts for <5% of SCD in the young. Rates of HCM-related SCD have been decreasing over the last two decades. Improved survival likely relates to improved case detection and medical management.Abstract Figure