| ObjectiveWe studied the culprit lesions,proximal and distal reference segments in patients with acute coronary syndromes(included acute myocardial infarctions and unstable angina pectoris) and in patients with stable angina pectoris before interventional therapy,measured the external elastic membrane cross-sectional area and lumen cross-sectional area,and calculated the plaque area, plaque burden, remodeling index and the direction of remodeling of each site, and compared the characteristics of each group to investigate the morphological and remodeling characteristics of coronary lesions in vivo with intravascular ultrasound, and to explore the relationship between plaque size,arterial remodeling ,lesion characteristics and clinical presentations.Methods1 73 cases of patients with coronary artery disease were studied using intravascular ultrasound before coronary intervention,55 cases were male, 18 cases were female,aged as 57.37+ 10.59 years(ranged 23 to 73 years).The patients were divided into three groups according to the clinical presentations:including the group of acute myocardial infarction, 27 cases; the group of unstable angina pectoris,22 cases; the group of stable angina pectoris,24 cases. The lesion site and a proximal reference site were analyzed .The external elastic membrane cross-sectional area and lumen cross-sectional area were measured,and the plaque area, plaque burden, remodeling index were calculated , and the direction of remodeling were determined. The characteristics of each group were compared.2 The selective coronary angiographys were performed according to theJudkins method,multiple projection views were taken.3 All IVUS studies were performed before any intervention and after the intracoronary administration of nitroglycerin 200 ug using a commercially available system (Boston Scientific Corp Ceivis ). The IVUS catheter was advanced distally to the lesion, and retrograde imaging was performed back to the proximally to the lesion (motorized pullback speed of 1 mm/s). The external elastic membrane and minimum lumen cross-sectional area (the minimum lumen area site) of the lesion sites and the proximal and distal reference sites were identified and measured. Plaque area was external elastic membrane cross-sectional area minus lumen cross-sectional area, plaque burden was plaque area divided by the external elastic membrane cross-sectional area.4 The calculation of remodeling index: The remodeling index was lesion external elastic membrane area divided by the proximal reference external elastic membrane cross-sectional area. We defined positive remodeling as a remodeling index of >1.05,negative remodeling as a remodeling index of <0.95, and neutral remodeling as a remodeling index between 0.95 and 1.05.5 The characterization of plaque: The characterization of plaque was qualitatively analysed according to the plaque composition. Hypoechoic plaque was less bright than the adventitia. Hyperechoic, noncalcified plaque was as bright or brighter than the adventitia without shadowing. Hyperechoic, calcified plaque was as bright or brighter than the adventitia with shadowing. Hypoechoic lesion within a plaque was >75% of the plaque , the plaque was considered "soft",otherwise, the plaque was considered "hard".Results1 There was no significantly differences among plaque area in ACS AMI UAP and SAPgroups.The plaque burden was significantly greater at culprit lesions in patients with acute coronary syndromes than in patients with stableangina pectoris2 The remodeling index was significantly greater in patients with acute coronary syndromes than in patients with stable angina pectoris(0.97 + 0.23 versus 0.79+0.13; P=0.003).The distribution of remodeling index in these two groups was different, Positive remodeling was more frequent in patients with acute coronary syndromes than in patients with stable angina pectoris (34.69% versus 4.17%,P=0.038), whereas negative remodeling was more frequent in stable angina pectoris (91.67% versus 46.94 % ,P=0.000).3 The remodeling...
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