The researchers call for a randomized clinical trial to confirm their analysis. Meanwhile, they advise cardiologists to begin treatment with sufficient doses of nitroglycerin to relieve pain before resorting to morphine.
In their analysis of the clinical data and outcomes of more than 57,000 high-risk heart attack patients -- 29.8 percent of whom received morphine within the first 24 hours of hospitalization -- the researchers found that those who received morphine had a 6.8 percent death rate, compared to 3.8 percent for those receiving nitroglycerin. The increase in mortality persisted even after adjustment for the patients' baseline clinical risk.
The results of the Duke were published as a fast-track article in the American Heart Journal.
"The results of this analysis raise serious concerns about the safety of the routine use of morphine in this group of heart patients," said Duke cardiologist Trip Meine, M.D., the study's lead author. "Since randomized clinical trials evaluating the safety or effectiveness of morphine for these patients have not been conducted, official guidelines for its use are based solely on expert conjecture. Given the adverse outcomes associated with morphine use found in our analysis, a randomized clinical trial is in order."
Morphine was first used to relieve the chest pain associated with heart attacks in 1912 and has been used regularly ever since. Nitroglycerin has been used for more than 130 years for the relief of chest pain, also known as unstable angina. It works by relaxing blood vessels and allowing blood flow to increase.
"Nitroglycerin has a physiological effect that may, at least temporarily, influence the underlying ischemia," Me