Epidemiological trends in hypertrophic cardiomyopathy in adults – a Swedish nationwide registry study

AIMS: Hypertrophic cardiomyopathy (HCM), entailing increased risk of heart failure and death, affects ∼200 per 100,000 populations, with incidence rates of 4-12 per 100,000 person-years. We investigated the epidemiological changes and mortality trends in HCM, with and without left ventricular outflow tract obstruction, in Sweden between 2003 and 2022. METHODS: Using the Swedish National Patient Register, we analysed data for patients 17-85 years of age diagnosed with HCM in inpatient or specialized outpatient care, categorized by age and by ICD-10 codes for obstructive (oHCM) and non-obstructive (nHCM) disease. Annual age- and sex-adjusted incidence, prevalence and all-cause mortality were calculated. Temporal and group differences were assessed using negative binomial regression. RESULTS: In total, 11,299 patients were analysed (mean age 62.9 years; 58.8% male; 67% nHCM). During the study period, the overall prevalence increased from 14 to 73 per 100,000 populations. The incidence increased from 5.1 to 9.3 per 100,000 person-years, largely due to nHCM, and with the steepest rise observed among middle-aged and older adults. Annual all-cause mortality declined from 9.8% to 4.3%, with similar rates for nHCM and oHCM at study end. Prognosis improved across all age groups, most notably among older age groups. CONCLUSION: Between 2003 and 2022, the prevalence of oHCM nearly quadrupled, while nHCM increased more than six-fold. Contributing factors include a nearly doubled incidence, primarily driven by a rise in nHCM, and halved all-cause mortality. These trends were most pronounced in older adults, consistent with increased detection of individuals with milder phenotypes.