Assessing composition of coronary thrombus in STEMI patients A multiscale approach to charaterize samples obtained by catheter aspiration

Percutaneous catheter thrombectomy allows collecting coronary thrombi from patients with ST-segment elevation myocardial infarction, preserving most of the sample characteristics available for both visual assessment and compositional analysis. This study aimed at identifying the association between thrombus macroscopic aspect and composition and, secondly, correlations between composition and ischemic time. Aspirated thrombi were grouped into "white", "red" or "mixed" according to their macroscopic appearance. Platelets, RBCs and fibrin were quantified on thrombus surface by SEM and on thrombus sections by a modified Carstairs histochemical staining. Fifty-three samples from 51 patients were included. The median [inter-quartile range] ischemic time was 210 [190-265] min. Seven (13%) "white", 19(36%) "mixed" and 27(51%) "red" thrombi were macroscopically identified. Median thrombus composition assessed by SEM was 23[11-41]%, 43[26-62]%, and 24[11-37]% for platelets, RBCs and fibrin respectively. Median histological analysis was 10[5-26]%, 45[31-64]% and 30[18-49]% for the same components. Significant difference in composition were found between "white" and "red" thrombi, showing respectively a higher amount of platelets (p=0.003) and fibrin (p=0.007). No significant correlations were found between composition and ischemic time suggesting that plaque instability and thrombus formation can occur before the symptom onset.