Abstract 14703: Platelet Reactivity and Long-Term Outcomes Following Acute Myocardial Infarction

Abstract

Introduction: A large volume of literature demonstrates a short term (1 year) association between high on treatment platelet reactivity in patients with acute myocardial infarction treated with clopidogrel and adverse cardiovascular outcomes. There is less literature examining whether this association extends beyond the duration of clopidogrel treatment. Hypothesis: That on-treatment platelet reactivity is associated wtih 5-year death and recurrent myocardial infarction in patients with acute myocardial infarction. Methods: We measured platelet reactivity in patients presenting with AMI to Wellington Hospital between 2012 and 2015 who had been treated with clopidogrel prior to angiography using Multiplate P2Y 12 assay (Roche Diagnostics). Platelet reactivity was measured in platelet reactive units (PRU). We examined the relationship between PRU and both death and myocardial infarction at 5 years follow-up. Results: In 921 patients with acute myocardial infarction (mean age 63.2, sd 10.8, 81% NSTEMI 19% STEMI) mean PRU was 39.3 (sd 23.6) PRU, with 74 patients (8%) having a PRU greater than 47, previously described as high on treatment platelet reactivity. 5-year mortality was observed in 10.4% (96 cases) and recurrent myocardial infarction in 12.2% (122 cases). Platelet reactivity was significantly associated with 5-year mortality in Receiver Operator Curve analysis, with AUC 0.58, p=0.009. Mean PRU was 45.8 (sd 27.5) in those who died versus 38.4 (sd 23.2) in those still alive at 5 years (p=0.004, unpaired t-test). Cox regression analysis demonstrated a hazard ratio of 1.01 (95% CI 1.003-1.017, p=0.01) for each increasing unit of PRU. Recurrent MI was not significantly associated with PRU, with an AUC of 0.55, p=0.09). Conclusions: Levels of platelet reactivity were associated with long-term mortality risk in AMI patients. This may suggest platelet reactivity in the acute phase following an AMI is a marker of poor cardiovascular repair, leading to an association with long-term mortality risk