Association of Race With Disease Expression and Clinical Outcomes Among Patients With Hypertrophic Cardiomyopathy

This cohort study assesses the association between race, disease expression, care provision, and clinical outcomes among patients with hypertrophic cardiomyopathy. Question Is race associated with differential disease expression, inequitable care provision, or disparate clinical outcomes among patients with hypertrophic cardiomyopathy? Findings In this cohort study of 2467 patients with cardiomyopathy, compared with white patients, black patients with hypertrophic cardiomyopathy were diagnosed at a younger age, were less likely to have sarcomere mutations, and had worse symptoms. Inequities in health care access and delivery were associated with race, with lower rates of genetic testing and invasive septal reduction therapy among black patients with hypertrophic cardiomyopathy. Meaning The findings suggest that racial differences in disease expression and adverse clinical outcomes exist between black and white patients with hypertrophic cardiomyopathy and that these differences may be associated with inequities in clinical care provision. Importance Racial differences are recognized in multiple cardiovascular parameters, including left ventricular hypertrophy and heart failure, which are 2 major manifestations of hypertrophic cardiomyopathy. The association of race with disease expression and outcomes among patients with hypertrophic cardiomyopathy is not well characterized. Objective To assess the association between race, disease expression, care provision, and clinical outcomes among patients with hypertrophic cardiomyopathy. Design, Setting, and Participants This retrospective cohort study included data on black and white patients with hypertrophic cardiomyopathy from the US-based sites of the Sarcomeric Human Cardiomyopathy Registry from 1989 through 2018. Exposures Self-identified race. Main Outcomes and Measures Baseline characteristics; genetic architecture; adverse outcomes, including cardiac arrest, cardiac transplantation or left ventricular assist device implantation, implantable cardioverter-defibrillator therapy, all-cause mortality, atrial fibrillation, stroke, and New York Heart Association (NYHA) functional class III or IV heart failure; and septal reduction therapies. The overall composite outcome consists of the first occurrence of any component of the ventricular arrhythmic composite end point, cardiac transplantation, left ventricular assist device implantation, NYHA class III or IV heart failure, atrial fibrillation, stroke, or all-cause mortality. Results Of 2467 patients with hypertrophic cardiomyopathy at the time of analysis, 205 (8.3%) were black (130 male [63.4%]; mean [SD] age, 40.0 [18.6] years) and 2262 (91.7%) were white (1351 male [59.7%]; mean [SD] age, 45.5 [20.5] years). Compared with white patients, black patients were younger at the time of diagnosis (mean [SD], 36.5 [18.2] vs 41.9 [20.2] years; P < .001), had higher prevalence of NYHA class III or IV heart failure at presentation (36 of 205 [22.6%] vs 174 of 2262 [15.8%]; P = .001), had lower rates of genetic testing (111 [54.1%] vs 1404 [62.1%]; P = .03), and were less likely to have sarcomeric mutations identified by genetic testing (29 [26.1%] vs 569 [40.5%]; P = .006). Implantation of implantable cardioverter-defibrillators did not vary by race; however, invasive septal reduction was less common among black patients (30 [14.6%] vs 521 [23.0%]; P = .007). Black patients had less incident atrial fibrillation (35 [17.1%] vs 608 [26.9%]; P < .001). Black race was associated with increased development of NYHA class III or IV heart failure (hazard ratio, 1.45; 95% CI, 1.08-1.94) which persisted on multivariable Cox proportional hazards regression (hazard ratio, 1.97; 95% CI, 1.34-2.88). There were no differences in the associations of race with stroke, ventricular arrhythmias, all-cause mortality, or the overall composite outcome. Conclusions and Relevance The findings suggest that black patients with hypertrophic cardiomyopathy are diagnosed at a younger age, are less likely to carry a sarcomere mutation, have a higher burden of functionally limited heart failure, and experience inequities in care with lower use of invasive septal reduction therapy and genetic testing compared with white patients. Further study is needed to assess whether higher rates of heart failure may be associated with underlying ancestry-based disease pathways, clinical management, or structural inequities.