Abstract 910: Distribution of Lipid-Rich Coronary Plaques in the Three Main Coronary Arteries
Distribution of ruptured or prone-to-rupture plaques is known to be nonuniform throughout the coronary tree. We sought to investigate whether plaques located in the left coronary artery differ in terms of lipid content from those located in the right coronary artery. Conventional and integrated backscatter intravascular ultrasound (IB-IVUS) using 40-MHz (motorized pullback 0.5mm/s) intravascular catheter was performed to 206 consecutive patients with 289 obstructive coronary lesions. The region of interest was subsequently divided into the proximal and distal segment to the minimum luminal area in the left anterior descending artery (LAD), in the left circumflex artery (LCX) or in the right coronary artery (RCA), respectively: The percentage of lipid area and fibrous area were automatically calculated by the IB-IVUS system. Three-dimensional analysis of IB-IVUS was performed to determine the percentage of lipid volume (% LV) and fibrous volume (% FV). % LV gradient was defined as proximal % LV/distal % LV >1. The study vessels were the LAD in 125 (43%) lesions, LCX in 56 (19%) lesions and RCA in 108 (37%) lesions. % LV was significantly increased in the proximal plaques compared with the distal plaques in the LAD (36 ± 15% vs. 29 ± 14%, p=0.0006). On the other hand, there were no significant differences in % LV between the proximal and distal plaques in the LCX (30 ± 15% vs. 27 ± 13%, p=0.25) and in the RCA (36 ± 14% vs. 34 ± 15%, p=0.22). On logistic regression analysis after adjusting for confounding factors, plaques located in the proximal LAD were significantly associated with the greater % LV gradient (odds ratio=2.06, 95% confidence interval, 1.23 to 3.44, p=0.006). Lipid-rich plaque composition was more frequent in the proximal LAD lesions and then decreased distally. The distribution of lipid plaques in the LCX and RCA artery were uniform throughout the coronary tree. These results may contribute to explain the reason why rupture or occlusion occurs more frequently in the proximal LAD.