A research study, led by the Ohio State University Wexner Medical Center, reveals the genetic nature of many cases of the heart muscle disorder dilated cardiomyopathy (DCM) and shows that Black families seem to have higher rates of inherited DCM than families of other ethnicities.
Writing in JAMA, the research shows that approximately 30% of DCM cases are inherited overall, but that this rate increases to 39% in Black individuals with DCM versus 28% in White individuals with the same condition. Hispanic patients had similar risk to White patients.
DCM and resulting heart failure and death are known to be more common in Black patients than White, but despite this many studies investigating DCM have not included Black patients.
“Integrating Black families into this DCM study was critically important because most information has only been available for white patients. Our study shows that families of Black patients are at greater risk for DCM than those of white patients,” said lead study author Ray Hershberger, a cardiologist and division director of human genetics at the Ohio State Wexner Medical Center, in a press statement.
DCM causes systolic dysfunction and enlargement of the left ventricle of the heart and can result from exposure to toxins, infections or other types of heart disease, but the exact cause of many cases of DCM are unknown. Many cases of ‘unknown origin’ are thought to be genetic, which Hershberger and team investigated in this study, as well as assessing the risk of family members.
The study included 1220 patients with DCM, 43% Black and 8% Hispanic, and also screened 1693 first-degree relatives for DCM. While the prevalence of familial DCM in the patients screened in the study was 12%, a statistical model estimated the rate of familial DCM at a typical heart failure clinic would be 30% if all first-degree relatives were also screened.
According to the study results, the prevalence of inherited DCM was predicted to be 11% higher in Black patients with DCM than White. But there was no significant difference in the rate between White and Hispanic individuals.
First-degree relatives of Black individuals with DCM were almost twice as likely to have DCM than those of White patients with DCM.
“DCM can be silent for months to years before symptoms begin. Eventually heart failure may develop, which is late-phase disease. Since medical treatment has been shown to mitigate asymptomatic DCM, guidelines have recommended that, with a diagnosis of DCM, the patient’s first-degree family members undergo clinical screening including an echocardiogram so that early asymptomatic DCM can be found and treatment initiated before progression to late-phase disease,” Hershberger said.
“For the first time, this study gives us hard numbers on how to counsel family members on their risk of developing DCM, and especially so for family members of Black patients with DCM.”
This study is the first of a series being carried out by the Dilated Cardiomyopathy Consortium, which is largely NIH funded. According to the project website, the consortium is conducting research “focused on the genetics and genomics of DCM, including discovery, mechanisms of disease, genetic epidemiology, clinical genetics, and precision medicine and its related questions of behavioral and implementation science.”