Platelet-leukocyte conjugates are increased in patients with coronary artery disease but the relationship between conjugate formation and myocardial ischemic outcome is unknown. We prospectively evaluated the relationship between conjugate formation and the development of recurrent myocardial ischemia in patients with acute coronary syndromes (ACS). Platelet-leukocyte conjugate formation (induced by thrombin receptor activating peptide (TRAP)) and platelet aggregation (induced by ADP and arachidonic acid) were assessed in 30 patients with unstable angina or non-ST elevation myocardial infarction. All patients were treated with β-blockers, aspirin, heparin, and GPIIb-IIIa antagonists and were followed for in-hospital recurrent myocardial ischemia. Troponin I and C-reactive protein (CRP) were also measured. Seven patients (23%) experienced recurrent ischemia. Platelet-neutrophil conjugates were greater in ischemic patients (59 ± 9 and 36 ± 4%, P = 0.007, for +ischemia and -ischemia, respectively). Platelet aggregation did not differ between ischemic and nonischemic patients, and there was no significant relationship between aspirin resistance and ischemic outcome. Troponin I was greater in patients who developed recurrent ischemia (3.04 ± 1.73 vs. 0.70 ± 0.21 ng/ml, P = 0.03, for +ischemia and -ischemia, respectively) but CRP was not. TRAP-induced platelet-neutrophil conjugate formation was an independent predictor of ischemic outcome (OR 1.07, 95% CI 1.00-1.15, for each 1% increase in conjugate formation). Receiver operator characteristic analysis showed platelet-neutrophil conjugates to have good ability to discriminate between ischemic and nonischemic patients (AUC of 0.84, P < 0.05). TRAP induced platelet-neutrophil conjugate formation is related to in vivo ischemic risk in ACS patients.
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