Abstract 5600: Coronary Artery Distensibility and Plaque Composition Determined by Virtual Histology-IVUS - Comparison between Stable Angina Pectoris and Acute Myocardial Infarction

The purpose of this study was to assess the difference in coronary artery distensibility and plaque composition determined by Virtual Histology-IVUS between non-culprit lesions of stable angina pectoris (SAP) and those of acute myocardial infarction (AMI). One-hundred thirty cross sectional areas (CSA) of 12 non-culprit de novo coronary artery lesions from 8 SAP patients and 128 CSAs of 12 non-culprit de novo coronary artery lesions from 10 AMI patients were imaged by IVUS (Volcano Therapeutics) with simultaneous intracoronary pressure (ICP) recording. Systolic and diastolic lumen areas (LA), vessel areas (VA), and plaque areas (PA) were measured. Lumen diameters (LD) were calculated with an assumption that the cross section was circular. Plaque burden; (PA/VA) X100, coronary compliance; {(LA change/diastolic LA)/(ICP change)} × 10 3 and stiffness index β (SI-β); {ln (systolic ICP/diastolic ICP)}/(LD change/diastolic LD) were calculated at each site. Color tissue maps were reconstructed from radio frequency data using IVUS-Virtual Histology software. Coronary compliance, SI-β and 4 tissue composition areas (Fibrous, Fibro-fatty, Dense-calcium and Necrotic core) were compared between SAP group and AMI group. LA, VA and PA were significantly larger in AMI group than in SAP group (7.88mm 2 vs 6.45 mm 2 , p<0.0001, 16.77 mm 2 vs 14.18 mm 2 , p<0.0001 and 8.88 mm 2 vs 7.73 mm 2 , p<0.0001). However, plaque burden showed no significant difference between AMI and SAP groups (53.4%vs 54.0%, p=0.60). Coronary compliance was significantly lower and SI-β was significantly higher in AMI group than in SAP group (0.82±0.75vs1.85±1.28, p<0.0001, 34.8±25.1vs 20.1±17.2, p<0.0001). Fibrous and Fibro-fatty areas were significantly smaller in AMI group than in SAP group (51.6% vs 71.3% p<0.0001, 10.1% vs 15.5% p<0.0001). Dense-calcium area and Necrotic core area were significantly larger in AMI group than in SAP group (15.2% vs 2.6% p<0.0001, 22.9% vs 9.9% p<0.0001). Coronary atherosclerosis assessed by Virtual Histology-IVUS was more advanced and severe, and coronary distensibility was impaired even in non-culprit lesions of AMI compared to those of SAP.