Platelet Reactivity and Intramyocardial Hemorrhage in Patients With ST-Segment Elevation Myocardial Infarction.

The aim of the study was to analyze the relation between platelet reactivity and intramyocardial hemorrhage (IMH) in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention. Platelet reactivity was measured in 49 patients with means of impedance aggregometry (Multiplate) before reperfusion and repeated in the subacute phase of STEMI. Cardiovascular magnetic resonance was used to detect IMH, which was found in 16 (33%) patients. There were no differences in platelet reactivity between patients with and without IMH before reperfusion. Reassessment in the subacute phase of STEMI demonstrated that patients with IMH had lower thrombin receptor activating peptide (TRAP)-induced platelet aggregation (P = .004) and trends toward lower values of ristocetin and collagen-induced platelet aggregation (P = .09 and P = .07). The TRAP-induced platelet aggregation and initial perfusion grade were the factors independently associated with IMH. Intramyocardial hemorrhage is related to more potent inhibition of platelet aggregation in the subacute phase of STEMI.