Use of intravascular ultrasound radio-frequency signals has shown that clinical effects of statin treatment include structural changes in coronary atherosclerotic plaques, according to a presentation at the annual congress of the European Society of Cardiology. The researchers noted that their findings on structural change over time after initiation of statin therapy explains at least in part why statins can reduce the risk for myocardial infarction after roughly 6 months of use.

Previous research with animal models had shown that statin use is associated with stabilization of coronary atherosclerotic plaques; primary changes in structure are an increase in fibrous tissue and a reduction in lipid. In the current study, Japanese researchers decided to use intravascular ultrasound radio-frequency signal analysis, an invasive diagnostic technique that can produce cross-sectional images of coronary arteries in real time.

They enrolled 42 consecutive patients who were admitted for percutaneous coronary intervention for severe angina. In the first step (baseline measurement), the arteries of each patient were explored with signal analysis to find and measure lipid-rich plaques in arteries that were not targets for the interventional procedure. Afterward, patients were randomized to atorvastatin 10 mg daily or to a control group that did not receive statin therapy. After a follow-up period of 6 months, imaging was repeated at the sites assessed in the baseline study.

The investigators found that plaque signals were significantly improved in the patients who had received atorvastatin but not in the control patients --- improvement was defined as changes reflecting an increase in fibrous tissue in the plaques. Researchers also found that greater reductions in low-density lipoprotein cholesterol were associated with greater improvement in plaque structure. In neither group was there a significant change in plaque volume over the 6 months of follow-up.

The authors concluded that statin therapy does alter plaque composition in the coronary arteries and that improvement in plaque structure parallels reduction in low-density lipoprotein cholesterol level.