Two leading beta-blockers improve the survival rate of patients who suffered heart attacks, according to a new study led by cardiologists at the University of Miami Miller School of Medicine. However, the beta-blocker carvedilol appeared to be more effective than metoprolol in patients whose left ventricles were unable to pump out an average amount of blood with each heartbeat.
The study, “Comparison of Metoprolol versus Carvedilol After Acute Myocardial Infarction,” was published February 19 in the American Journal of Cardiology. Ghaith Zaatari, M.D., postdoctoral research associate, was the lead author, and Jeffrey J. Goldberger, M.D., M.B.A., professor of medicine and chief of the Cardiovascular Division, was the senior author of the collaborative study, which was written on behalf of the Outcomes of Beta-blocker Therapy After Myocardial INfarction (OBTAIN) Investigators.
“Metoprolol and carvedilol are two of the most common beta-blockers prescribed after a heart attack or acute myocardial infarction (AMI) as they reduce heart rate and blood pressure, and improve blood flow,” said Dr. Goldberger. “However, carvedilol may have additional pharmacological properties that may provide added benefits to some patients.”
In the new study, the researchers analyzed data from the OBTAIN registry, which included more than 4,000 AMI patients in the U.S. and Canada who were prescribed metoprolol at discharge and more than 1,000 patients prescribed carvedilol.
Overall, the three-year survival estimates were 88.2 percent for the patients given metoprolol and 83.5 percent for the carvedilol group. The patients treated with carvedilol were slightly older and had more comorbidities. After adjusting for differences in comorbidities, the difference between the two drugs was no longer significant.
However, the researchers found one key difference in patients with depressed left ventricular ejection fraction (LVEF) – an indicator of how much blood the heart chamber pumps out with each heartbeat. For patients with an LVEF of 40 percent or lower, carvedilol was associated with improved survival compared with metoprolol. For patients with an LVEF higher than 40 percent, there were no differences in survival.
“Our results suggest that outcomes with carvedilol may be superior to metoprolol only in patients with left ventricular ejection fraction of 40 percent or less,” said Dr. Zaatari. “Further validation of these findings with prospective trials is warranted.”