Prevalence of Sarcomeric Hypertrophic Cardiomyopathy in 31,325 Consecutive Forensic Autopsies from Portugal.

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is the most common monogenic cardiac disorder, with an estimated prevalence of approximately 0.2%. Its clinical expression is highly variable, ranging from asymptomatic disease to heart failure and sudden cardiac death. This study aimed to determine the prevalence and clinicopathological characteristics of HCM in a nationwide forensic autopsy series from Portugal.

METHODS

We analyzed 31,325 consecutive forensic autopsies performed at the Portuguese National Institute of Legal Medicine and Forensic Sciences between 2017 and 2022. HCM was identified using strict macroscopic and histopathological criteria. Demographic, cardiac, and extracardiac data were collected. Statistical analyses included prevalence estimates, χ² tests, analysis of variance, and odds ratios, with p<0.05 considered statistically significant.

RESULTS

Fifty-two cases met the diagnostic criteria for HCM, corresponding to a crude prevalence of 0.17%. After standardization to the contemporary Portuguese population, the age-adjusted prevalence was 0.19% (95% CI: 0.13-0.26%). Prevalence was higher in males than females (0.20% vs 0.07%; OR=2.91; p=0.015) and varied significantly across regions, reaching its highest value in southern Portugal (0.30%; 95% CI: 0.21-0.45%; p<0.0001). Most deaths were natural, with cardiovascular causes accounting for the majority of cases. A concentric pattern of left ventricular hypertrophy was observed in 59.6% of cases, while histological examination revealed myocardial fibrosis in 69.2% and cardiomyocyte disarray involving >15% of the myocardium in all cases. Only 3.8% of individuals had been diagnosed with HCM during life.

CONCLUSION

This nationwide forensic autopsy study provides the first population-based estimate of HCM prevalence in Portugal. The observed prevalence is comparable to that reported in other populations, and highlights the substantial under-recognition of HCM during life, underscoring the value of systematic post-mortem investigation in identifying heritable cardiomyopathies.