INTRAVASCULAR ULTRASOUND IMAGING IN PATIENTS WITH ACUTE MYOCARDIAL-INFARCTION - COMPARISON WITH CHRONIC STABLE ANGINA-PECTORIS

Background: Myocardial infarction is the result of acute thrombotic oc clusion of a coronary artery, most likely secondary to rupture of an a therosclerotic plaque. Intracoronary ultrasonic (ICUS) examinations we re performed in patients with acute myocardial infarction (AMI) in ord er to describe intraluminal ultrasonic findings at the site of acute c oronary occlusion. Methods: Coronary angiography and ICUS studies were performed consecutively within 6 h of the onset of chest pain in 30 p atients with AMI prior to percutaneous transluminal coronary angioplas ty (PTCA). The control group consisted of 30 patients with chronic sta ble angina pectoris (SAP). Following angiographic documentation of a p roximal stenosis or occlusion, a 3.5 or 4.8 F mechanical ultrasound ca theter (20 MHz) was advanced successfully through the lesion in 25 of 30 (83%) patients with AMI and in 15 of 30 (50%) patients with SAP (P< 0.01). Results: Intracoronary ultrasound permitted differentiation bet ween pulsatile, low-echogenic intraluminal material suggesting thrombu s and mural highly echogenic atherosclerotic plaque in 22 of 25 (88%) patients with AMI. A negative imprint of the ICUS catheter was documen ted within the low-echogenic material in 17 of 25 (68%) patients with AMI. Low-echogenic intraluminal material was found in 18 of 25 (72%) s egments proximal and in 12 of 25 (48%) segments distal to the highly e chogenic plaque, indicating prestenotic and post-stenotic thrombus in AMI. The plaque appeared eccentric in 22 of 25 (88%) patients with AMI . In comparison, stenotic lesions in chronic SAP patients were less fr equently eccentric (5/15, 33%, P<0.01) and contained a higher proporti on of pure highly echogenic material (12/15, 80%). Cross-sectional are a stenosis due to highly echogenic plaque averaged 52+/-13% in AMI and 82+/-3% in SAP (P<0.01). Calcification of plaque was evident in 21 of 25 patients with AMI ( SAP 12/15, 80%, NS). The surface of the plaque was rough in 13 of 25 (52%) AMI patients (SAP 4/15, 27%, P<0.05). Fis sures were detected in only seven (28%) patients and dissection was ob served in two (8%) cases. The low incidence might be a result of the l imited resolution of the ICUS system. Conclusion: This study demonstra tes that ICUS with 4.8 or 3.5 F catheters is feasible and safe in sele cted patients with AMI, and adds little to the overall duration of the angioplasty procedure. The identification and demarcation of atherosc lerotic plaque provided by ICUS could prove valuable in guiding PTCA, in deciding on appropriate therapy, and in acute and long-term follow- up of AMI patients.