Aim: It is well known that platelet volume indices are associated with adverse outcomes following percutaneous coronary intervention(PCI). In this study, we investigated the hypothesis whether the association between platelet size and clinical outcomes is the result of high residual platelet reactivity after antiplatelet therapy in patients with large platelets.
Methods: Between February 2010 and December 2011, a total of 462 consecutive patients with coronary artery disease who were scheduled to undergo planned PCI were enrolled in this study. The degree of platelet aggregation induced by arachidonic acid(AA) and adenosine diphosphate(ADP) was assessed using the Multiple Electrode Platelet Aggregometry(Multiplate(®), Dynabyte, Munich, Germany)(MEA) test. We simultaneously measured the mean platelet volume(MPV) in the same period(Sysmex XE-2100, Mundelein, IL).
Results: The study population consisted of 462 consecutive patients, including 371 stable angina patients and 91 acute coronary syndrome patients. The patients with large platelets(upper quintile of MPV ≥10.6 fL) had significantly high residual platelet reactivity after both aspirin(MEA ASP 9 [5-14] Units vs. 13 [8-18.5] Units, p < 0.001) and clopidogrel(MEA ADP 21 [15-30] Units vs. 24 [18.5-40] Units, p=0.003) treatment. According to a multivariate analysis, having large platelets was independently associated with high residual platelet reactivity after both aspirin (OR 2.52, 95% CI 1.50-4.24, p < 0.001) and clopidogrel(OR 2.86, 95% CI 1.59-5.15, p < 0.001) treatment. Platelet volume indices were not associated with any differences in the incidence of major adverse cardiac events during follow-up.
Conclusions: Platelets with a higher volume are associated with high residual platelet reactivity after conventional dual antiplatelet therapy.