Sustained enhancement of residual platelet reactivity after coronary stenting in patients with myocardial infarction compared to elective patients

INTRODUCTION: Elevated platelet reactivity despite antiplatelet therapy is associated with an increased cardiovascular risk after percutaneous coronary interventions. Current guidelines recommend uniform antiplatelet maintenance regimen after percutaneous coronary interventions for patients with myocardial infarction and elective patients. We sought to demonstrate that there is a persistent enhancement of residual platelet reactivity after myocardial infarction, requiring an intensified antiplatelet maintenance therapy. MATERIALS AND METHODS: A total of 66 patients after coronary stenting for myocardial infarction (n=36) or elective coronary stenting (n=30) were included in this prospective, controlled study. Platelet reactivity to adenosine-5-diphosphate and arachidonic acid under treatment with clopidogrel (75mg) and acetyl salicylic acid (100mg) were assessed 48hours and 30days after coronary stenting using light transmission aggregometry and multiple electrode platelet aggregometry (Multiplate analyzer) simultaneously. RESULTS: Fourty-eight hours after coronary stenting all measures of residual platelet reactivity were significantly elevated in the infarction group. After a mean follow up of 37days, residual platelet reactivity to adenosine-5-diphosphate was still consistently elevated, albeit statistically not significant. Contrarily, residual platelet reactivity to arachidonic acid significantly decreased and returned to normal by the time of follow up. Regression analyses revealed myocardial infarction, C-reactive protein and fibrinogen as predictors of enhanced platelet reactivity 48hours after coronary stenting. CONCLUSIONS: Patients undergoing coronary stenting for acute myocardial infarction exhibit an enhancement of residual platelet reactivity sustaining for at least 48hours following coronary stenting. This finding provides a rationale for a continued intensified antiplatelet therapy after myocardial infarction