The results of a new study suggest that black patients with congestive heart failure are at higher risk for death and for worsening of their disease than similarly treated white patients.
"Congestive heart failure is a devastating disease affecting 600,000 black patients. If research confirms a difference between black and white survival and identifies the underlying cause of this difference, we may see improved treatment of blacks with heart failure and a greater understanding of this disease among all patients," said Dr. Claude Lenfant, Director of the National Heart, Lung, and Blood Institute (NHBLI), which funded the study.
The new findings, published in the February 25 issue of the New England Journal of Medicine, are based on data collected from the Studies of Left Ventricular Dysfunction (SOLVD). SOLVD found that patients with chronic congestive heart failure had fewer deaths and hospitalizations when treated with an ACE inhibitor, a drug which blocks the constriction of blood vessels.
In the new "retrospective" analysis, Dr. Daniel Dries of the NHLBI and colleagues looked back at the SOLVD results and analyzed racial differences. They reported that 42 percent of blacks in the treatment component of the study (patients with symptoms) and 22 percent of blacks in the prevention component (without symptoms) died compared to 36 and 14 percent of whites respectively. In addition, black patients were at increased risk for progression of the disease.
Although other research has shown that the death rate for congestive heart failure is more than twice as high in black patients as in whites, not all studies have come to this conclusion. Some studies have attributed differences in death rates to factors such as differences in access to care or differences in the severity of the disease. Other studies have not found a racial difference.
In the new study, the higher risk of death and disease progression among black patients was found even after the scientists adjusted the data to minimize any influences from age, other coexisting medical conditions, severity and causes of heart failure, socioeconomic status, and medications. Also, since SOLVD is a clinical trial, management and followup of patients was standardized.
Dr. Dries and his colleagues speculate that the differences between blacks and whites with heart failure may be due to physiological differences in the neuroendocrine and renin/angiotensinogen systems. These systems release various hormones affecting heart rate and blood flow in response to the heart's decreased ability to pump blood. Over time, it is believed that the initial beneficial effect of these hormones is stopped and instead they actually contribute to the progression of heart failure.
The neuroendocrine system governs "catecholamines," a group of hormones that includes norepinephrine; the renin/angiotensinogen system involves the release of angiotensin II.
Black patients with heart failure may have a greater activation of the neuroendocrine rather than the renin/angiotensinogen system, suggest the study's authors. Another possible explanation is that ACE inhibitors, which block the renin/angiotensinogen system, may be less effective in halting the progression of the disease in black compared to white patients. ACE inhibitors are commonly used to treat heart failure.
If future studies confirm this racial difference, there may be implications for improved treatment of black patients with heart failure.
For example, some previous studies have suggested that when used alone for the treatment of hypertension, ACE inhibitors may be less effective in black patients. Beta-blockers, on the other hand, antagonize or "block" the neuroendocrine system. If further research finds that the neuroendocrine system is overactive in black patients, they may be ideal candidates for early therapy combining beta blockers with ACE inhibitors.
"The stakes are high ? over 4 ½ million people have congestive heart failure and hospitalizations for this disease are on the rise," said Dr. Lenfant. "The NHLBI is committed to conducting further research not only to confirm this apparent racial difference but also to find ways to improve the treatment of all patients with heart failure."
To arrange an interview with Dr. Daniel Dries, please call the NHLBI Communications Office at (301) 496-4236.