Scavenger receptor A index and coronary thrombus in patients with acute ST elevation myocardial infarction

To examine the relationship between the scavenger receptor A (SRA) index (the number of SRA+ cells observed in 10 high power fields of peripheral blood (PB) smear samples; normal upper limit <30) and coronary thrombus, 389 thrombi obtained from 393 patients with acute ST elevation myocardial infarction were examined. Thrombi were classified into platelets (PT), mixed (MT), fibrin-rich (FT) and organizing thrombi (OT); 387, 269, 57 and 29 cases were detected, respectively. Patients were divided into group A (PT only, 89 cases), B (containing MT and PT but not FT, 243 cases), and C (containing FT, 57 cases). SRA+ cells had infiltrated into all FT cases and 147 of the 269 MT, but no PT. At hospitalization, the SRA index exceeded 30 in 276 patients. PT was observed in 274 cases, and MT and FT (residual mural thrombus; RMT) observed in 230. Infarct-related coronary artery was thought to be totally and rapidly occluded by PT that had formed as a result of severe stenosis due to extrusion of plaque content or growth of RMT. An abnormal increase of SRA+ cells is considered to be a useful finding to detecting the presence of PT and, probably, RMT.