Atherosclerotic Plaque With Ultrasonic Attenuation Affects Coronary Reflow and Infarct Size in Patients With Acute Coronary Syndrome : An Intravascular Ultrasound Study

Background No reflow following percutaneous coronary intervention (PCI) is a major concern in patients with acute coronary syndrome (ACS) and it may be influenced by the preexisting plaque type. Methods and Results To evaluate the impact of plaque characteristics on coronary reflow following PCI in patients with ACS, a total of 110 patients (89 acute myocardial infarction, 21 unstable angina) were assessed by intravascular ultrasound. Plaque type was categorized as either atherosclerotic plaque without ultrasonic attenuation (group 1) or atherosclerotic plaque with attenuation (group 2). External elastic membrane, plaque plus media, and lumen area were measured. Coronary flow was assessed by Thrombolysis in Myocardial Infarction (TIMI) grade and TIMI frame count. Although the final TIMI frame count was similar between the 2 groups, TIMI frame count immediately after the first balloon inflation was significantly higher in group2 (p=0.03). Despite the similar final TIMI grade and TIMI frame count, peak creatine kinase level was significantly higher (3,035±2,553 vs 1,950±1,958IU/L, p=0.04) and fatal arrhythmia more frequently observed (16.4% vs 2.7%, p=0.04) in group 2 than in group 1. Conclusions Atherosclerotic plaque with ultrasonic attenuation may be related to a transient deterioration in coronary flow and as a result larger infarct size and higher incidence of fatal arrhythmia following PCI in patients with ACS. These results may help in selecting lesions suitable for distal protection devices.