Quantitative effect of atorvastatin on size and content of non-calcified plaques of coronary arteries 1 year after atorvastatin treatment by multislice computed tomography.

PURPOSE

Intensive lipid-lowering treatment with Atorvastatin reduced progression of coronary atherosclerosis, confirmed by IVUS. To quantitate the effect of Atorvastatin on the size and content of non-calcified coronary plaques (NCP) using multislice CT (MSCT) and by comparison of LDL cholesterol levels.

MATERIALS AND METHODS

Twenty-one subjects (16 males, 35-79 years, median 69) with NCP by MSCT (Light Speed Ultra 16, GE) were enrolled. All were asymptomatic thereby distinguishing NCP from thrombi in coronary arteries. Following LDL cholesterol measurements, all were given 10 mg of Atorvastatin (2 were given 5 mg as LDL cholesterol levels were already <70 mg/dl) for 1 year, at which point MSCT and LDL cholesterol measurements were repeated. One remarkable NCP was selected in each subject and evaluated as representative of the effect of Atorvastatin. The area and CT values for NCP, excluding calcified portions, were manually measured from axial source or multiplanar reconstruction images under the same conditions using an workstation (Virtual Place Advance Plus, AZE).

RESULTS

Twenty-one NCPs (18 left anterior descending branch, 2 left circumflex branch, and 1 right coronary artery) were evaluated. Mean LDL cholesterol levels were 122 mg/dl at the first scan and significantly decreased to 96 mg/ml at the second scan (P<0.05). The NCP areas were 2-31 mm(2) (mean 11.8) at the first scan, and 2-32 mm(2) (mean 12.6) at the second scan. These differences were not significantly different. The averages of CT values were 15-91 HU (mean 55 HU) at the first scan and 38-114 HU (mean 62 HU) at the second scan. SDs of CT values of the two scans were 14-64 HU (mean 40 HU) and 20-68 HU (mean 45 HU), respectively. The averages and SDs of CT values were significantly higher in the second scan (P<0.05). There was a weak but significant positive correlation between ratios (%) of change in area to baseline area at first scan of NCPs (y) and LDL cholesterol levels (x) after 1 year of Atorvastatin treatment (y=0.0106x-0.7265, R(2)=0.1514, R=0.39, P<0.05).

CONCLUSION

Using MSCT, we could quantitate the effect of Atorvastatin to the size and content of NCP and compare those with LDL cholesterol levels. Atorvastatin may decrease area of NCP if LDL cholesterol levels are sufficiently reduced. Also, it may increase CT values, which could suggest a change in NCP composition. LDL cholesterol levels may be an important factor in decreasing NCP area. Further studies are needed using 64-slice MSCT in a larger population exhibiting greater decreases in LDL cholesterol levels.