TUESDAY, April 1 (HealthDay News) -- Researchers found that giving patients MC-1, a naturally occurring metabolite of vitamin B6, before and after bypass surgery didn't reduce the risk of heart attack or cardiovascular death.

"Coronary artery bypass graft (CABG) surgery is one of the most important therapeutic options for relieving angina and improving survival and quality of life in patients with multi-vessel coronary artery disease," the Duke University scientists wrote. "It is the most commonly performed cardiac surgical procedure in the world, and, in 2005, more than 250,000 CABG procedures were performed in the United States."

But CABG surgery can lead to serious complications such as heart attack, recurrent angina, kidney problems, stroke and death. Previous research suggested that MC-1 may lower the risk of heart attack or death in high-risk patients.

A new phase 3 multi-center, randomized trial of MC-1 included 3,023 intermediate- to high-risk patients undergoing CABG surgery with cardiopulmonary bypass. It found that cardiovascular death or nonfatal heart attack 30 days after surgery occurred in 140 of 1,510 patients (9.3 percent) who received MC-1 and in 133 of 1,486 patients (9.0 percent) who received a placebo.

All-cause death was 1 percent in the MC-1 group and 0.3 percent in the placebo group at four days, and 1.9 percent in the MC-1 group and 1.5 percent in the placebo group at 30 days.

Both groups had similar levels of postoperative stroke, atrial fibrillation, kidney function, and intensive care unit and hospital lengths of stay.

The findings show that "among intermediate- to high-risk patients undergoing CABG surgery, MC-1, 250 mg/d, given immediately before and for 30 days following surgery did not reduce cardiovascular death or nonfatal (heart attack)," the study authors wrote. "Myocardial injury remains a significant problem following CABG surgery. Effective therapies to reduce perioperative morbidity and mortality are needed but remain elusive."

The study was expected to be presented April 1 at the American College of Cardiology annual meeting and was published online in the Journal of the American Medical Association. It was also expected to be published in the April 16 print issue of the journal.

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