Increasing co-documentation of secondary pulmonary hypertension among U.S. decedents with hypertrophic cardiomyopathy: a national mortality analysis (1999–2020)
G Shanmuganathan, P ParwaniAbstract
Background
Hypertrophic cardiomyopathy (HCM) is associated with diastolic dysfunction and elevated left atrial pressures that may lead to secondary pulmonary hypertension (PH). Population-level data on PH trends among HCM decedents remain limited.
Purpose
To characterise the temporal trends and demographic patterns of secondary PH among U.S. decedents with HCM.
Methods
Using the CDC WONDER multiple-cause-of-death database (1999–2020), we identified decedents with HCM (ICD-10: I42.1, I42.2) as underlying cause and secondary PH (I27.2) as contributing cause. Age-adjusted mortality rates were standardised to the 2000 U.S. population. Joinpoint regression estimated annual percent change (APC) with 95% confidence intervals. Trend analysis was restricted to 2003–2020 due to suppressed cell counts (<10 deaths) in earlier years. Chi-square tests compared demographic distributions. Sensitivity analysis excluded 2020 to assess pandemic effects.
Results
Among 40,897 HCM decedents from 1999–2020, 798 (1.95%) had documented secondary PH. The proportion increased significantly from 2003 to 2020 (APC 7.35%, 95% CI 6.08–8.97; p<0.001), with no inflection points identified. In contrast, HCM age-adjusted mortality rates declined from 2003–2014 (APC −5.41%, p<0.05) and plateaued thereafter. Findings remained consistent after exclusion of 2020. The proportion of HCM decedents with PH increased significantly across age strata (χ² for trend = 357.8, p<0.001), rising from 0.35% among individuals aged 15–24 years to 3.70% among those ≥85 years. The mean age of HCM+PH decedents was 73.5 ± 15.3 years. HCM+PH decedents were more frequently female compared with HCM-only decedents (71.8% vs 42.3%; χ² = 276.7, df = 1, p<0.001). Racial distribution differed significantly between groups (χ² = 6.91, df = 2, p = 0.031). The proportion of HCM decedents with documented PH was highest among White individuals (2.04%), followed by Asian/Pacific Islander (1.91%) and Black/African American decedents (1.56%). PH documentation also differed by Hispanic ethnicity (χ² = 12.62, df = 1, p<0.001), with lower representation among Hispanic decedents (1.09%) compared with non-Hispanic decedents (2.02%). Place of death differed significantly between groups (χ²=185.9, df=4, p<0.001). Compared with HCM-only decedents, HCM+PH decedents were more likely to die in hospital or institutional settings such as hospice and nursing/long-term care facilities, and substantially less likely to die at home.
Conclusion
Secondary PH is increasingly documented among HCM decedents and is associated with older age, female sex, and institutional death. These observational findings do not establish causality, but suggest a later-stage HCM phenotype and warrant prospective imaging studies to clarify underlying mechanisms.HCM_PHTN_proportion trendHCM_age_adjusted_mortality_trend