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CHICAGO -- A new drug therapy designed to lower risk of heart attack, stroke or death following heart bypass surgery has failed to meet its goals, say researchers from the Duke Clinical Research Institute.

Results of the trial, involving more than 3000 patients at 130 sites throughout the U.S., Canada and Germany, were released today at the annual meeting of the American College of Cardiology. The results are also available on the Journal of the American Medical Association Web site.

The new therapy, called MC-1, contains pyridoxal 5'-phosphate, a naturally-occurring metabolite of vitamin B6. It had shown promise in earlier trials in similar patients, according to John Alexander, MD, a cardiologist at Duke University Medical Center and a lead investigator of the trial. But in comparing patients who got the drug versus those who did not in this most recent study, researchers found no difference in outcomes between the two groups.

Coronary bypass surgery (CABG) is the most common cardiac surgical procedure in the world, with about a quarter million surgeries in the U.S. in 2005. Even though mortality from the procedure has declined over time, patients who undergo it still face significant risk of life-threatening conditions.

"There is controversy around the definition of myocardial infarction in patients undergoing CABG surgery; however, the data from MEND-CABG II and other recent clinical trials support the fact that a significant number of patients do have myocardial injury during surgery," said Alexander.

Researchers had hoped MC-1 would lessen heart muscle damage that occurs during reperfusion – the process when the patient is taken off the bypass machine and blood is re-introduced into the system.

In the MEND-CABG II study, 9.3 percent of the patients who got the drug suffered a heart attack, stroke or death at some point up to 30 days after bypass, compared with 9 percent of those who did not get the drug.

"We are obviously disappointed with these results. This is an area of significant medical need. MC-1 is one of many compounds that has been tried but has failed to reduce the myocardial damage associated with cardiac surgery."

The study was funded by Medicure, a Canadian company that manufactures MC-1.