Study Finds Racial Differences in HCM

Black patients with hypertrophic cardiomyopathy (HCM) are less likely to have classic characteristics of the disease than White patients, which could lead to delays in diagnosis and treatment, according a research findings reported recently in the Journal of the Ameirican Heart Association.

The researchers compared the characteristics, comorbidities, and outcomes of two patient cohorts — one with 57 Black HCM patients and the other with 377 White patients. Black patients have been unrepresented in studies of HCM, a chronic, progressive disease in which excessive contraction of the heart muscle can lead to the development of debilitating symptoms and cardiac dysfunction. The condition is characterized by a thickening of the muscular tissue of the heart. Symptoms include shortness of breath, chest pain and cardiac arrhythmias. It’s estimated that 1 in every 500 people have HCM but a large percentage of patients are undiagnosed, according to the American Heart Association.

In this study of Black and White differences, Milla E. Arabadjian, RN, Ph.D., of the NYU Rory Meyers College of Nursing, and her co-investigators found that Black patients were more likely to have apical hypertrophy, a variant of HCM. They were also more likely to have apical‐mid and mid‐ventricular left ventricular hypertrophy (LVH), as well as diffuse hypertrophy. Black individuals also had significantly more mid‐ventricular obstruction.

“While the existing literature shows that Black patients are less likely to be obstructed than White patients, we did not observe that in our sample. We found that Black individuals had significantly more mid‐ventricular obstruction, which is also a novel finding. The discrepancy between our findings and the existing literature may be because mid‐ventricular obstruction has been underevaluated and under‐recognized in existing research,” wrote Arabadjian and her colleagues.

Black and White patients had similar rates of insertion of implantable cardioverter defibrillators for primary prevention: 13 (22.8%) Black patients had an ICD inserted versus 76 (20.2%) White patients.

The researchers' analysis found, though, that Black patients had a significantly higher rate of ICD ventricular antichycardia pacing (ATP) therapy, which uses pulses to interrupt a tachycardia (a racing heartbeat) episode and restore the heartbeat to a normal rhythm.

Both groups had a similar number of comorbid conditions; notably, the Black patients were significantly younger and more likely to have moderate obesity.

Genetics play a causative role in HCM, but investigators found that less than half of the patients in both cohorts underwent genetic testing. Investigators said that the literature examining genetic testing usage rates between Black and White HCM patients is limited.