Disparities in Black Americans' Responses to Heart-Failure Therapies May Signal Different Disease

An emerging database of genetic variations in black Americans may explain the differences in their response to traditional heart-failure therapies, according to a researcher at UT Southwestern Medical Center at Dallas.

The fact that traditional therapies are less-effective among blacks than whites points to the possible need for unique heart-failure management strategies, said Dr. Clyde Yancy in an article published in the May issue of Current Cardiology Reports.

"The distinct natural history, cause of the heart failure, prognosis and response to treatment suggest that heart failure in blacks is likely to be a different disease," said Yancy, associate professor of internal medicine. "The physiology of the heart and blood vessels may differ, and there may be certain other differences that are determined by variation in genetic signals. Much work needs to be done in this area, but there is a growing curiosity that a genetic basis may exist to explain some of the differences in outcomes that are seen in black patients with heart failure."

Heart failure affects 3 percent of black Americans, or 660,000 people, and several factors account for this high incidence. The disease occurs at an earlier age in blacks, and hypertension, or high blood pressure, also appears to more aggressively affect other organs in the body, resulting in an increase in stroke and kidney failure.

Results from recent clinical trials show that blacks are twice as likely to suffer from and die of heart failure compared to nonblacks.

"A much higher incidence of hypertension as a potential cause of heart failure in blacks is now evident and may be associated with related alterations in pharmacologic responsiveness to cardiovascular treatments," said Yancy.

To further evaluate the response to heart-failure therapies, Yancy and other investigators initiated a multicenter trial last year called the African-American Heart Failure Patients trial.

The study is the first prospective heart-failure trial conducted exclusively for black patients. The researchers will evaluate the safety and efficacy of the heart failure drug BiDil, a vasodilator that opens blood vessels by relaxing the muscle walls.

"This trial is part of an ongoing effort to capture a large enough denominator of African-American patients with heart failure to get a better handle on their clinical scenario and to characterize, from a genetic standpoint, the profile of African-Americans with heart failure. We also aim to determine if there is a consistent genetic pattern that can be seen in the plurality of the patients that may suggest that there is an over-expression of one particular common genetic pattern," Yancy said.

In a study published last year, Yancy found that the beta-blocking drug carvedilol reduces the risk of death and the symptoms of mild to moderate heart failure in black patients as well as it does in nonblack patients. Beta-blockers previously have been shown to be less effective in blacks. This was the first study to evaluate whether race influences the response to the relatively new beta-blocker carvedilol as a treatment of heart failure.

Although differences in the response to medical therapy have been described, beta-blockers and angiotensin-converting enzyme (ACE) inhibitors -- two of the most common heart-failure therapies -- remain the most appropriate therapy to treat heart failure in blacks until more definitive data are available, Yancy said.