Abstract 11761: Association of Red Blood Cell Microparticles With Biomarker-Defined Infarct Size in Acute Myocardial Infarction

Abstract

Background: Red blood cell microparticles (RBCm) have drawn research attention as to their potential prothrombotic and vasoconstrictive effects in experimental settings. Our group has previously reported elevated RBCm counts in patients with ST-elevation myocardial infarction (STEMI) treated with primary percutaneous intervention (PCI). Methods: Circulating microparticles were quantified with flow cytometry in blood samples from consecutive STEMI patients after primary PCI. Creatine kinase myocardial-brain fraction (CK-MB) was measured every 6 hours during the first 3 days and every 12 hours thereafter until discharge. The area under the CK-MB concentration curve (CKMB-AUC), calculated with Simpson’s summing rule, was used as a biochemical measure of infarction size. Results: 51 STEMI patients (age 59.8±8.8 years) were enrolled. RBCm concentration was 33740±21169 /μl. The median values [25th-75th percentile] of CKMB-AUC according to RBCm quartile were (from the lower to the upper quartile) 3351 [2550-4060] ng.h.ml-1, 4883 [4179-5348] ng.h.ml-1, 6932 [5464-13229] ng.h.ml-1, and 8784 [7216-12605] ng.h.ml-1, respectively (Kruskal-Wallis p<0.001) (see Figure). In a multivariable regression analysis, RBCm quartile remained associated with CKMB-AUC, after adjustment for total RBC count, age, serum creatinine, presence of diabetes and Killip class on admission (adjusted p<0.001). Conclusions: Erythrocyte microparticles appear to be related to total myocardial damage biomarker output, which is a parameter known to reliably reflect infarct size in patients with STEMI. This finding may be explained by rheologic and vasoactive properties of RBCm (close interaction of the heavily oxidative heme with the endothelium, depletion of NO etc.), which may act deleteriously on coronary vasculature, resulting in increased myocardial damage.