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Race and Hypertrophic Cardiomyopathy Disease Expression
Study Questions:
Is there an association between race and disease expression, care provision, and clinical outcomes among patients with hypertrophic cardiomyopathy (HCM)?
Methods:
In a retrospective cohort study, data were examined from US-based sites of the Sarcomeric Human Cardiomyopathy Registry from 1989 through 2018. Potential differences based on self-identified black or white race were assessed in baseline characteristics, genetic architecture, adverse outcomes (including cardiac arrest, cardiac transplantation or left ventricular assist device [LVAD] implantation, implantable cardioverter-defibrillator (ICD) therapy, all-cause mortality, atrial fibrillation, stroke, and New York Heart Association [NYHA] functional class III or IV heart failure), and septal reduction therapies. An overall composite clinical outcome was the first occurrence of any component of a ventricular arrhythmic composite endpoint, cardiac transplantation, LVAD implantation, NYHA class III or IV heart failure, atrial fibrillation, stroke, or all-cause mortality.
Results:
Of 2,467 patients with HCM at the time of analysis, 205 (8.3%) were black (130 male [63.4%], mean age 40.0 ± 18.6 years) and 2,262 (91.7%) were white (1,351 male [59.7%], mean age 45.5 ± 20.5 years). Compared with white patients, black patients were younger at the time of diagnosis (mean 36.5 ± 18.2 vs. 41.9 ± 20.2 years, p < 0.001), had higher prevalence of NYHA class III or IV heart failure at presentation (36 of 205 [22.6%] vs. 174 of 2,262 [15.8%], p = 0.001), had lower rates of genetic testing (111 [54.1%] vs. 1,404 [62.1%], p = 0.03), and were less likely to have sarcomeric mutations identified by genetic testing (29 [26.1%] vs. 569 [40.5%], p = 0.006). Implantation of ICDs did not vary by race; however, invasive septal reduction was less common among black patients (30 [14.6%] vs. 521 [23.0%], p = 0.007). Black patients had less incident atrial fibrillation (35 [17.1%] vs. 608 [26.9%], p < 0.001). Black race was associated with increased development of NYHA class III or IV heart failure (hazard ratio [HR], 1.45; 95% confidence interval [CI], 1.08-1.94), which persisted on multivariable Cox proportional hazards regression (HR, 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 clinical outcome.
Conclusions:
This study suggests that black patients with HCM are diagnosed at a younger age, are less likely to carry a sarcomere mutation, have a higher burden of functionally limiting heart failure, and experience inequities in care with lower use of genetic testing and invasive septal reduction therapy compared to white patients. The authors concluded that further study is needed to assess whether higher rates of heart failure are associated with differences in underlying ancestry-based disease pathways, differences in clinical management, or structural inequities.
Perspective:
Racial differences exist in the general cardiology population, including worse heart failure outcomes among black patients in a setting of disparate quality of care. However, the association of race with disease expression and outcomes among patients with HCM has not been well characterized. This study found that black patients with HCM are diagnosed at a younger age, have more advanced heart failure, and experience lower use of genetic testing and septal reduction therapies. Although the observations may at least in part be due to ancestry-based differences in cardiac remodeling, additional study is of importance to determine to what degree clinical outcome differences are caused by racial disparities in access to care.
Keywords: African Americans, Arrhythmias, Cardiac, Atrial Fibrillation, Cardiomyopathy, Hypertrophic, Defibrillators, Implantable, Genetic Testing, Health Status Disparities, Heart Arrest, Heart Failure, Heart Transplantation, Heart-Assist Devices, Mutation, Outcome Assessment, Health Care, Sarcomeres, Stroke
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