Many trials with the cholesterol-lowering statin drugs have shown that major reductions in the rates of cardiovascular events were associated with only minor decreases (called regression) in the apparent amount of atherosclerotic plaque in the coronary arteries. Two aspects of a clinical trial called ASTEROID have allowed the demonstration of impressive reductions in the volume of atherosclerosis.

First, the ASTEROID trial (a memorable acronym for its less memorable full title, "A Study to Evaluate the Effect of Rosuvastatin on Intravascular Ultrasound-Derived Coronary Atheroma Burden") measured changes in the amount of atherosclerosis using intravascular ultrasound (IVUS) rather than the more conventional coronary artery angiography.

Angiography can only estimate the apparent size of plaques from the extent of artery narrowing, whereas IVUS gives a measure of the extent of atherosclerosis within the artery wall as well as the amount of plaque narrowing the artery.

In addition ASTEROID used the highest possible dose of the most potent statin. A total of 349 patients had IVUS evaluations of atherosclerotic volume at the start of the trial and again 24 months later. During the trial they took 40 mg of rosuvastatin (Crestor) daily. Their LDL cholesterol fell from an average of 130 mg/dL to 61 mg/dL (a 53 percent reduction) and their average HDL cholesterol rose from 43 mg/dL to 49 mg/dL (a 15 percent increase).

At the end of 24 months there were highly significant reductions in the percent of atherosclerotic volume overall and in the segment of the artery with the greatest severity of disease at the beginning of the study.

These results add considerable weight to the evidence that aggressive treatment to lower LDL cholesterol and raise HDL cholesterol can not only improve cardiovascular outcomes but also lead to regression of established atherosclerotic disease.

Though side effects were uncommon during this trial, many patients should not be taking the highest dose of a statin because the frequency of side effects tends to increase as the dose of a statin is raised.