Background: Ruptured plaque and culprit lesions associated with anterior acute myocardial infarction cluster mainly in the proximal segment of the left anterior descending coronary artery (LAD). This study investigated whether the tissue characteristics of plaque in the proximal LAD differs from that of plaque in the distal LAD as assessed by integrated backscatter (IB)-intravascular ultrasound (IVUS).
Methods and results: IVUS interrogation was used to study 107 non-culprit intermediate plaques in 68 patients with angina pectoris who underwent percutaneous coronary interventions. Proximal and distal segments were defined as <30 mm and > or =30 mm from the ostium, respectively. IB-IVUS images were recorded, and the average percentage values of each plaque component (lipid, fibrosis, dense fibrosis, and calcification) were compared between segments. Plaques in the proximal segment (n=51) had a higher %lipid content (36 vs 19%, P<0.01) and a lower %fibrosis content (57 vs 64%, P<0.01) than did plaques in the distal segment (n=56). Multiple linear regression analysis showed that proximal plaques had a higher %lipid content, independently of other coronary risk factors and plaque burden (P<0.01).
Conclusions: The %lipid and %fibrosis contents differ significantly between plaques in the proximal segment and those in the distal segment of the LAD. (Circ J 2010; 74: 142 - 147).