CHICAGO (AP) -- A six-month regimen of folic acid, vitamin B12 and vitamin B6 can help prevent reoccurrence of blocked arteries in patients who have undergone coronary angioplasty, a study found.

The findings, reported in Wednesday's Journal of the American Medical Association, are an extension of a clinical trial that examined effects of the vitamin combination on treating heart disease.

The treatment apparently works by lowering levels of homocysteine, an amino acid long implicated in heart attacks.

Dr. Guido Schnyder, an assistant professor in the cardiology division at the University of California at San Diego, and his colleagues conducted both studies.

The earlier study, reported in the New England Journal of Medicine in November 2001, involved 205 patients who were given either the vitamin combination of folic acid, vitamin B12 and vitamin B6 or a placebo for six months.

During that period, the patients who took the vitamin combination showed a 48 percent reduction in the development of restenosis, or renarrowing of the vessel, compared to patients who received the placebo.

In the new study, Schnyder added 348 patients and extended the follow-up observation period from six months to one year.

"It was important to follow these patients for another six months because that's the time frame in which restenosis typically occurs," he said. "We've now shown that the vitamin combination didn't just delay the development of restenosis, it prevented it."

Schnyder also expanded the study's focus to look at the patient's need for repeat angioplasties or heart bypass operations. He said the vitamin regime decreased by 38 percent the need for repeat angioplasties or heart bypass operations.

Dr. Robert Bonow, chief of cardiology at Northwestern Memorial Hospital in Chicago and president of the American Heart Association, said the study offers more evidence that B vitamins are important in maintaining healthy blood vessels. More research is needed, though, he said.

"When you have a small trial like this, it's always nice to have confirmation by another group," Bonow said. "I think it's very interesting and it needs to be followed very carefully."

The study was funded by the Swiss National Science Foundation and Swiss Cardiovascular Center and the University Hospital in Bern, Switzerland.

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