Chicago ? 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 today’s Journal of the American Medical Assn., 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, assistant professor in the cardiology division at the University of California at San Diego, and 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 on 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 looked at the patient’s need for repeat angioplasties or heart bypass operations. He said the vitamin regime decreased the need by 38 percent.