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ESC Congress 2003: Amount of blood LDL reduction relates to change of coronary plaque composition.

August 31, 2003

IMPORTANT: This press release accompanies a poster or oral session given at the ESC Congress 2003. Written by the investigator himself/herself, this press release does not necessarily reflect the opinion of the European Society of Cardiology

We successfully demonstrated the clinical effect of statin on structural changes of coronary atherosclerotic plaques using intravascular ultrasound (IVUS) radio-frequency (RF) signal analysis and explained the reason why statin could reduce the risk of heart attack after 6 months of administration in several mega-trials with statin for prevention of heart attack.

The major cause of heart attack (acute coronary syndrome) has been thought to be the rupture of an atheromatous plaque in coronary arterial walls and the rupture-prone plaque has more lipid components and less fibrous tissues. Several clinical mega-trials have demonstrated that statins which are kinds of blood-cholesterol-lowering medicines can reduce the number of recurrent heart attacks or episodes of angina (chest pain) in patients with previously revealed coronary artery disease. Regarding the mechanism of statin's action, some animal studies showed that statin could stabilize a coronary atheromatous plaque, increasing fibrous tissues and decreasing lipid components and prevent the rupture. However, the effects of statin on human coronary atherosclerotic plaques and the relation between blood-lipid-lowering and structural changes of the plaques have not been well investigated in clinical settings. IVUS is one of the invasive diagnostic imaging methods and can provide cross-sectional images of coronary arterial walls in real time. We already reported that the parameters calculated in analysis of the RF signals reflected from human coronary plaques in an IVUS examination were useful to quantitatively evaluate histological structures of the plaques.

The purpose of our study was to assess whether statins alter the structure of coronary atherosclerotic plaques in a manner clinically detectable by IVUS-RF analysis.

Our study was carried out in Chiba University Hospital, Chiba, Japan and funded by Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science. We enrolled 42 consecutive patients undergoing percutaneous coronary intervention (PCI) due to episode of severe angina. We searched for lipid-rich plaques in non-PCI-targeted coronary vessels using a 40 MHz IVUS catheter after PCI procedure and acquired the RF signals reflected from the plaques. The patients were randomly assigned into two groups: Group S taking atrovastatin 10 mg / day and Group C as control without statin. At 6-month follow-up, the RF signals were sampled again at the same plaque sites using an IVUS catheter. Some parameters derived from the RF signals, the plaque volumes calculated in the IVUS cross-sectional images and blood LDL (low density lipoprotein) levels were compared between baseline and the 6-month follow-up.

In results, the RF parameters significantly changed in Group S but not in Group C, the change of which meant increase of fibrous tissue in the objective coronary plaques. The more LDL cholesterol decreased, the more RF parameters changed. Plaque volumes did not significantly change in both groups during 6 months.

Our findings suggested that statin may increase fibrous component in human coronary plaques within 6 months and the effect of statin on the plaques could be measured by the amount of decrease of blood LDL cholesterol level.

Professor Nobuyuki Komiyama
Center for Cardiovascular Interventions
Chiba University Hospital
1-8-1 Inohana Chuo-ku, Chiba, 260-8677
Japan

European Society of Cardiology (ESC)