WASHINGTON – A cholesterol-lowering drug has for the first time been shown to shrink blockages that cause most heart attacks, indicating such pills may offer the first non-surgical way to start to clear clogged arteries.

An international study involving more than 500 patients found that high doses of a “statin” drug began to reverse the buildup, causing dangerous plaques lining the artery walls to recede. Statins are already widely used to prevent or slow heart disease.

“This may be the beginning of a real revolution in the treatment of heart disease,” said Steven Nissen of the Cleveland Clinic, who led the study released Monday at a meeting of the American College of Cardiology in Atlanta. “We’re not merely slowing down the inexorable progression but truly reversing the disease. It’s very exciting.”

While more research is needed to confirm the findings and determine whether the shrinkage will translate into fewer heart attacks and strokes, other researchers said the findings could mark an important step forward in treating heart disease. They predicted the results would accelerate the trend of doctors using cholesterol drugs much more aggressively.

“This is very exciting for those of us who take care of patients,” said Roger Blumenthal of Johns Hopkins University School of Medicine, who wrote an editorial that will accompany the findings in the April 5 issue of the Journal of the American Medical Association. “This is the first study showing you can take a pill for two years and get some actual reversal of disease.”

Some experts, however, questioned the findings, saying they were difficult to interpret because the researchers failed to compare patients who received the intensive treatment with those who did not. Consumer advocates have also raised safety concerns about the statin used in the study, Crestor.

Heart disease, the nation’s leading killer, occurs when plaques build up inside artery walls. The accumulations can burst, forming clots that block blood flow to the heart and brain, causing heart attacks and strokes. Patients take statins to slow or even stop the narrowing of arteries and can undergo surgical procedures to bypass or reopen clogged arteries. But until now there has been no way to reverse the disease.

“That’s always been just a dream – actually making the disease go away,” Mr. Nissen said.

In their study, Mr. Nissen and his colleagues gave 507 patients in the America, Canada, Europe, and Australia with mild to moderate heart disease the maximum dose – 40 milligrams – of Crestor. The drug caused low-density lipoprotein (LDL) cholesterol levels to drop from about an average of 130.4 to 60.8, a 53% reduction and the biggest drop ever shown in a study.

When the researchers compared the results of ultrasound tests of the arteries of 349 patients before and after two years of treatment they found the volume of plaque inside their arteries had diminished by between 6.9% and 9.1%.