Healthcare, Genetic Testing Disparities Persist in Black Patients With Hypertrophic Cardiomyopathy

December 19, 2019

Hypertrophic cardiomyopathy (HCM) is an inherited condition in which mutations in genes that encode the sarcomere proteins in the heart cause an abnormal thickening of that muscle, with no known cure. In black patients, HCM is usually diagnosed at a younger age and accompanied by a greater burden of symptomatic heart failure. These patients, however, are not well represented in surveys of the condition, which tend to focus on white patients.

Black patients with hypertrophic cardiomyopathy (HCM), an inherited, abnormal thickening of the heart muscle that has no known cure, tend to have the condition diagnosed at an earlier age, with a greater burden of symptomatic heart failure (HF). However, they are not well represented in studies of the condition, caused by mutations in genes that encode the heart muscle’s sarcomere proteins, as these studies tend to focus on white patients with HCM.

A recent study in JAMA Cardiology investigated the connection between race and HCM, factoring in disease expression, care provision, and clinical outcomes among black patients. The investigators wanted to better understand how these factors are interrelated in the care of black patients, especially with these patients having such a high rate of cardiovascular mortality, they noted.

Data were analyzed on 2467 patients with HCM from the Sarcomeric Human Cardiomyopathy Registry. Of these patients, 205 (8.3%) were black and 2262 (91.7%) were white. The mean (SD) ages were 36.5 (18.2) years versus 41.9 (20.0) years, respectively. New York Heart Association (NYHA) class III or IV HF occurred more often in black patients (22.6% [36/205]) compared with white patients (15.8% [174/2262]), and the former group was also more likely to have background high blood pressure (36.6% vs 26.3%).

Black patients also were not referred to subspecialty care as often. In particular, septal reduction therapy, a surgical procedure meant to reduce the obstruction caused by HCM, according to Cleveland Clinic, was used 57.5% less often in black patients compared with white patients.

Genetic testing took place in 54.1% and 62.1% of the 2 groups, respectively, and black patients were less likely to have sarcomeric mutations (26.1% vs 40.6%). However, in those black patients who did have sarcomeric HCM, there was also a 4-fold greater risk of NYHA class III and IV HF.

The authors also saw that black patients had a higher likelihood of “a variant of unknown significance” compared with white patients (12.6% vs 9.2%), which they posited “likely reflects the relative paucity of representative ancestry inclusion in reference cohorts and insufficient genotyping of black patients with HCM. Thus, variant classifications algorithms do not accurately predict pathogenicity in historically underrepresented minorities.”

One additional factor regarding genetic testing disparity among black patients with HCM is the lack of cascade screening of at-risk family members, which can help to identify and avert HCM-related complications. Overall, black patients were less likely to have their HCM diagnosed through family screening.

The study authors offer several solutions for overcoming these testing and healthcare disparities in black patients with HCM:

  1. Include more individuals of African ancestry in genomic investigations.
  2. Improve the methods used to differentiate variant pathogenicity.
  3. Address the genetic testing and counseling needs all groups.
  4. Diversify patient cohorts when investigating potential ancestry-based differences in hypertrophic remodeling and fibrosis.
  5. Measure HF severity in a way that complements the NYHA classification differences previously mentioned.

“To date, nearly all studies of disease expression and prognosis in HCM reflect the experience of white patients. As diseases-modifying therapies to interrupt progressive remodeling and adverse outcomes in HCM are investigated, increased attention to equity appears to be important,” the investigators concluded.

Reference

Eberly LA, Day SM, Ashley EA, et al. Association of race with disease expression and clinical outcomes among patients with hypertrophic cardiomyopathy [published online December 4, 2019]. JAMA Cardiol. doi: 10.1001/jamacardio.2019.4638.