Beta-Blockers in the Real World: Help for Some, but Not for ‘Stiff Hearts’
Beta-blockers can help older patients with heart failure live longer lives, but only if their condition is caused by a poorly-functioning left ventricle, say researchers at the Duke Clinical Research Institute.
The finding, available online and slated to appear in the Jan. 13 issue of the Journal of the American College of Cardiology, could lead to clarification of professional guidelines on beta-blocker drug use among older patients.
Heart failure can arise from a number of underlying conditions, but they all lead to similar symptoms -- fatigue, breathlessness and often, early death. Physicians divide patients into two groups, those who have weakened left ventricles, a condition known as left ventricle systolic dysfunction (LVSD), and those who have normally-functioning left ventricles, or preserved systolic function, a condition commonly known as a "stiff heart." Approximately three-quarters of patients with heart failure are over age 65 and about half of them fall into the stiff heart category.
"We don't really understand the underlying pathophysiology of heart failure among patients in that latter group," says Dr. Adrian Hernandez, a cardiologist at Duke University Medical Center and the lead author of the study. "We do know, however, that patients with "stiff hearts" tend to be older women who generally have just as poor outcomes as others with compromised ventricular function."
Current guidelines call for beta-blocker use in patients with weakened left ventricles, but they are silent on the use of the drugs among patients with normal left ventricles.
"There is very little information about how these drugs work in patients with preserved ventricular function," says Hernandez. We wanted to conduct this study for that reason, but we also thought it was important to discover how beta-blockers work among patients in real-life settings."
Professional guidelines are based upon findings from large, clinical trials. But such studies tend to include disproportionate numbers of younger, healthier patients, quite unlike those most commonly encountered in hospital or community practice settings, "so it is not entirely clear that the findings would be the same," says Hernandez.
Investigators examined hospital records of 7,154 patients with heart failure in a national quality improvement registry, the OPTIMIZE-HF registry, a program designed to support better management of heart failure patients. The study population reflected the types of patients normally seen in community settings: The median age for the patients in the current study 78 (compared to a median age of 65 among heart failure patients enrolled in clinical trials), and a significant number of the study patients had multiple health problems. All were all eligible to undergo beta-blocker therapy.
Researchers divided the patients into two groups, those who had poorly pumping ventricles (LVSD) and those who had preserved ventricular function and then merged the clinical records with Medicare data so they could track the patients as long as possible.
"We found that there were significantly higher death and rehospitalization rates after one year among our study population when compared with those found among younger, healthier, study populations," says Hernandez.
Investigators discovered that upon discharge from the hospital, 60 percent of the patients with weakened ventricles were prescribed beta-blockers, compared with 39 percent of the patients with stiff hearts.
After adjusting for variables that could account for some of the differences between the two groups, researchers found that those with weakened ventricles who took beta-blockers experienced a 23 percent lower risk of death and an 11 percent lower rate of rehospitalization, compared with those were not prescribed the drugs.
Among patients with preserved systolic function, beta-blockers appeared to have no significant impact on lowering the risk of death or rehospitalization.
Hernandez says the study is valuable because it offers new information about beta-blocker use among elderly, sicker patients with heart failure - the kind of patients physicians are likely to see in their community settings, and specifically for those with preserved systolic function. "Clinical trials can tell us if a drug works in a select population, but it's important to conduct additional studies to see if the drug works equally well in a population at large," says Hernandez.
The study was funded by GlaxoSmithKline.
Gregg Fonarow, from the University of California at Los Angeles, is the senior author of the study. Co-authors from the Duke Clinical Research Institute include Bradley Hammill, Christopher O'Connor, Kevin Schulman, and Lesley Curtis.