Intensive therapy with statin drugs may not just stall deterioration of the arteries but actually reverse it, research suggests.
The build-up of fatty deposits inside the arteries - atherosclerosis - can trigger cardiovascular disease.
An international study of 349 patients over two years found high doses of a powerful new statin, rosuvastatin, could break down the deposits.
Details were presented to an American College of Cardiology meeting.
Cardiovascular disease kills 233,000 people a year in the UK, and an estimated 16.7 million a year world-wide.
The fatty deposits inside arteries can trigger problems by breaking off and blocking blood flow.
Dr Sarah Jarvis, a London GP and member of the Royal College of General Practitioners, described the results as "dramatically exciting".
She said: "We have a drug that can not only halt the progression of the disease but, in the vast majority of patients, it actually showed the disease regress."
Professor Peter Weissberg, medical director of the British Heart Foundation, said the study was "important".
But he said it was yet to be demonstrated that breaking down the fatty deposits would actually mean fewer heart attacks.
The study focused on patients with cardiovascular disease at centres in the US, Canada, Europe and Australia.
They were given intensive treatment with rosuvastatin, known commercially as Crestor, which, along with other statins, was known to cut cholesterol levels.
Patients received at least one 40mg pill of the drug a day - most statins are more commonly used in doses of 10mg or 20mg/day.
Tests found that the drug cut levels of potentially damaging LDL-cholesterol by about 50% and boosted levels of the beneficial HDL form by around 15%.
As harmful cholesterol was reduced, build-ups of fatty deposits in the patients' arteries also showed signs of a reduction.
After two years of treatment their thickness was reduced by 6.8% - and even more so in particularly diseased parts of a blood vessel.
The research found almost four out of five patients (78%) demonstrated some reduction in the level of atherosclerosis.
The reductions were found to be greatest in the arteries with the most severe disease.
Professor Weissberg said: "Previously it was thought that statins saved lives by stabilising plaques - the build-up of fatty deposits in the arteries - thereby preventing them from rupturing to cause a heart attack or stroke.
"This study encouragingly seems to demonstrate a small but definite regression of atherosclerotic plaques.
"However, this study wasn't designed to test whether this treatment actually saves lives, so whilst the results sound promising and are likely to translate into a better outcome for heart patients, we still need further studies to confirm whether the regression demonstrated translates to fewer heart attacks."
Rosuvastatin has previously been linked to a small number of cases of a muscle wasting disease.
However, the drug was given a clean bill of health by the US Food and Drug Administration last year.
A British Heart Foundation spokesman said statins were extremely safe drugs.
However, he said it might not be practical - or economically viable - to put large numbers of patients on a high dose of one of the most potent forms of the drug.
Side effects are more likely at higher doses of drug.
Rosemary Leonard, a London GP and medical broadcaster, said: "These researchers used an incredibly high dose of a statin drug.
"There have been warnings about using this high a dose, and GPs certainly don't start with this high a dose."
The study, which was funded by AstraZeneca, the makers of rosuvastatin, will be published in the Journal of the American Medical Association in April.