Incomplete inhibition of platelet function as assessed by the platelet function analyzer (PFA-100) identifies a subset of cardiovascular patients with high residual platelet response while on aspirin.

摘要

Sixty-six patients with a history of ischemic events (myocardial infarction, unstable angina, or stroke) on chronic aspirin therapy were studied by different platelet function tests: 37 patients had suffered a recurrent event while on aspirin and 29 were without recurrences. Based on results from light transmission aggregometry (LTA) induced by arachidonic acid (AA) and serum TxB(2) both COX-1-dependent methods, only one patient could be identified as aspirin resistant activity were considered, the prevalence of aspirin non-responders ranged, according to the different tests, from 0 to 52%. No difference was observed between patients with recurrences and those without. Among patients with recurrent events, those with an incomplete inhibition of platelet function, as assessed by the PFA-100, had significantly higher residual serum TxB(2) (2.4 +/- 2.4 ng/mL vs 0.4 +/- 0.1 ng/mL, p = 0.03), residual LTA-AA (9.2 +/- 10.6% vs 2.0 +/- 1.6%, p = 0.008), LTA-Coll (49.3 +/- 14.6% vs 10.2 +/- 8.3%, p = 0.007) and LTA-ADP (50.9 +/- 16.2% vs 34.3 +/- 11.0%, p = 0.04). In conclusion, laboratory tests solely exploring the AA-mediated pathway of platelet function, while being the most appropriate to detect the effect of aspirin on its pharmacologic target (platelet COX-1), may fail to reveal the functional interactions between minimal residual TxA(2) and additional stimuli or primers potentially leading to aspirin-insensitive platelet aggregation. High residual platelet response in platelet function tests only partially dependent on COX-1 may reveal a condition of persistent platelet reactivity in a subset of aspirin-treated patients characterizing them as a subgroup at higher vascular risk.