MRI Scan Reveals How Cholesterol Drugs Work

July 5, 2005 -- High-tech scans may show how cholesterol-lowering statin drugs work to prevent heart disease.

In a new study, high resolution MRI (magnetic resonance imaging) scans showed that treatment with statins shrank artery-clogging plaques in people with high cholesterol.

Researchers say those plaque-fighting benefits were in addition to statins' already proven effects of lowering LDL "bad" cholesterol levels in blood.

Atherosclerotic plaque can rupture. A "vulnerable" plaque which ruptures leads to clots that cause heart attacks and strokes. Reducing LDL cholesterol in blood helps reduce the risk of heart disease.

"In the mostly average patients, if you are able to achieve an LDL lower than 100 milligrams per deciliter, you will be able to significantly avoid plaque progression and you may even induce plaque regression," says Juan J. Badimon, PhD, of the Mount Sinai School of Medicine in New York City, in a news release.

Statins May Shrink Plaques

In the study, which appears in the Journal of the American College of Cardiology, researchers followed 51 people recently diagnosed with high cholesterol. On scanned images, all the participants had plaque lesions of the major vessel. They received either 20 milligrams or 80 milligrams of Zocor daily.

After a year and a half of treatment, MRI scans showed that both groups ended up with similar reductions in plaque size, regardless of the strength of their statin dose.

Although this study used MRI to measure the effect of statin treatment on reducing plaque size, researchers say not every person using statins needs to have their arteries scanned.

Reduction in the size of blood vessel wall plaque was greater in people whose LDL cholesterol dropped below 100 mg/dl. Therefore, monitoring LDL cholesterol can also be used to gauge the effectiveness of statin therapy.

In addition, the group that received the higher statin dose experienced a 46% reduction in LDL levels compared with a 36% reduction in LDL among those with the lower dose.

The researchers note that the group assigned to receive the higher dose also had higher LDL levels at the start of the study. However they reached similar absolute reductions in cholesterol.

"The change in blood vessel wall [plaque size] is more related to LDL reduction rather than to the dose of statin," they conclude.

Merck, which makes Zocor, partially funded the study, but researchers conducted the study without any input from those supplying the funds. Merck is a WebMD sponsor.