Intravascular ultrasound imaging in patients with acute myocardial infarction.

Myocardial infarction is the result of acute thrombotic occlusion of a coronary artery secondary to rupture of an atherosclerotic plaque. Intracoronary ultrasonic examinations (ICUS) were performed in patients with acute myocardial infarction in order to describe intraluminal ultrasonic findings at the site of an acute coronary occlusion. Coronary angiography and ICUS studies were performed consecutively within 6 h after the onset of chest pain in 50 patients with acute myocardial infarction (AMI) prior to percutaneous coronary angioplasty (PTCA). Following angiographic documentation of a proximal occlusion, a 3.5 mechanical ultrasound catheter (30 MHz) was advanced successfully through the lesion in 42 of 50 patients (84%). In 37 of the 42 patients (88.1%), ICUS differentiated between pulsatile, low echogenic, intraluminal material suggesting thrombus, and mural more highly echogenic atherosclerotic plaque. A negative imprint of the ICUS catheter was documented within the low echogenic material in 25 of 42 (60%) patients with AMI. Low echogenic intraluminal material was found in 31 of 42 (73.4%) segments proximal to the highly echogenic plaque and in 28 of 42 (66.7%) segments distal to it, indicating pre- and post-stenotic thrombus in AMI. The plaque appeared eccentric in 32 of 42 patients (76.2%) with AMI. Cross-sectional area stenosis due to highly echogenic plaque averaged 48 +/- 14%. Calcification of plaque was evident in 35 of 42 patients (83.3%) and the surface of the plaque was rough in 30 of 42 (42.4%). Fissures were found in 10 (23.8%) and a dissection was detected in four (9.5%) cases.