''The disease is stopped in its tracks, and there is actually a reversal of disease,'' said Dr. B. Greg Brown, UW professor of medicine and director of the research, which is reported in today's edition of The New England Journal of Medicine.

Patients in the study took simvastatin, one of the statin class of anti-cholesterol drugs, and niacin, a vitamin of the B-complex group long touted as being good for the heart.

More than half of the 12 million Americans with coronary-artery disease could benefit from the treatment, Brown estimated. It both raises ''good cholesterol,'' which helps prevent heart disease by removing fats from the blood, and lowers ''bad cholesterol,'' which causes a buildup of artery-blocking plaque.

Sponsored by the National Heart, Lung and Blood Institute, the research also found that a combination of anti-oxidants - vitamins C and E, beta carotene and selenium - did not help reduce heart problems, as other research has suggested it might. Instead, the vitamins blunted the beneficial effect of simvastatin and niacin.

''I used to tell my patients to take the vitamins ... but I don't now,'' Brown said.

He is a pioneer in the use of statin drugs to lower cholesterol, directing the first study, involving lovastatin, that decreased arterial blockage and heart attacks. Statins are now commonly given to people with heart disease when diet and exercise don't sufficiently lower cholesterol. A statin generally reduces cardiovascular risk by about 35 percent over five years of treatment.

The new research showed that adding niacin to simvastatin, sold under the brand name Zocor, is a dramatic improvement. The combination both stops the narrowing of coronary arteries - even slightly reducing the blockage - and reduces the risk of fatal and nonfatal heart attacks, strokes and procedures for chest pain by a range of 60 to 90 percent.

''It's like getting hearing improvement from having a hearing aid in one ear and then putting them in both ears and getting even more improvement,'' said Brown.

Scientists from the UW, the University of British Columbia in Vancouver and the Oklahoma Medical Research Foundation in Oklahoma City participated in the research. They studied 160 patients with low levels of HDL, the good cholesterol, and with normal levels of LDL, the bad cholesterol. This is typical of 40 percent of all patients with heart disease.

The patients were separated into four groups and were studied for three years: One group received simvastatin and niacin; another received only anti-oxidants; another received all the treatments; another received placebos.

In the simvastatin-and-niacin group, the average HDL level increased 26 percent, and the average LDL level dropped 43 percent. Anti-oxidants reduced these effects, though researchers were unsure why.

Simvastatin and niacin also caused an average 0.7 percent reduction in arterial blockages, but the blockages increased slightly in the other groups, including a 1.9 percent increase in the anti-oxidant group.

Brown said similar results probably would occur with other statin drugs, though simvastatin was the only cholesterol-lowering drug used in the study. The combination treatment also probably would benefit patients with high triglycerides and borderline-high LDL, Brown said, ''though that has not been proved.''

One statin drug, Baycol, or cerivastatin, was recalled last spring after 31 deaths stemming from muscle destruction were reported among users. At the time, some health experts also criticized other statin drugs for causing muscle pain in some patients.

Brown said the combination treatment used a low dose of simvastatin and that none of the patients experienced muscle pain.