Intravascular Ultrasound Imaging in Patients with Acute Myocardial Infarction

Background：Even after efficacious thrombolytic therapy in patients with acute myocardial infarction, angiographic studies demonstrated significant thrombotic remnants in many patients which makes it difficult to identify the morphological characteristics of the pure underlying plaque of the lesion. The purpose of the current study is to assess the morphological characteristics and calcification of the plaque, and the thrombi remnants in the occluded segments of infarct-related artery in acute myocardial infarction by intravascular ultrasound (IVUS). Methods：Coronary angiography and IVUS studies for the infarct-related arteries were performed at about 6 days after the onset of chest pain in 22 patients (male 19 patients) with acute myocardial infarction (AMI). Fifteen patients had been treated with thrombolytics, and all patients received an intravenous infusion of heparin and oral aspirin. Results：1) Coronary angiography demonstrated total occlusion in 2 cases, and angiographic % diameter stenosis was 74.5±18.1%. 2) IVUS identified the soft plaque in 10 cases (45.5%) and the hard plaque with or without calcification (54.5%). Plaque rupture was observed in 4 cases, and in one case, slight depression of a part of the plaque without definite rupture suggestive of the plaque erosion was noted. Intraluminal echogenic material suggesting thrombi was documented in 8 (36.4%). 3) % Diameter and % luminal cross-sectional area stenosis on IVUS was 49.0±