Abstract 18373: Validating ARMYDA-PRO/BLEEDS: a Therapeutic Window in Platelet Reactivity for Patients Undergoing Elective Percutaneous Coronary Intervention

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Aims. Platelet reactivity has been shown to be an important determinant of both thrombotic and bleeding events in patients undergoing percutaneous coronary intervention (PCI). Recently, the ARMYDA-PRO study has shown that a threshold of P2Y12 reaction units (PRU) >240, measured with the VerifyNow assay, is associated with increased risk for thrombotic events at 30 days, while the ARMYDA-BLEEDS study has shown that a threshold of PRU <189 is associated with a increased risk of bleeding events. We aimed at validating the aforementioned PRU thresholds in an independent population of 640 patients taking clopidogrel and aspirin and undergoing elective PCI. Methods and results. Platelet reactivity was measured immediately before the procedure with the VerifyNow P2Y12 assay. Primary end point was the 30-day incidence of net adverse clinical events (NACE), defined as the occurrence of major adverse cardiac events (MACE) or major bleeding/significant entry site complications, in relation to the PRU distribution. Patients were divided in 3 groups on the basis of PRU values: low-PRU (240). At 30-day follow-up, patients in the low-, medium- and high-PRU groups presented an incidence of MACE of 4.6%, 5.0% and 14.6%, respectively (p for trend <0.001), and an incidence of major bleeding or significant entry site complications of 8.8%, 2.2% and 1.5%, respectively (p for trend <0.001). The incidence of NACE was 13.4% in the low-PRU group, 7.2% in the medium-PRU group (p=0.040 vs. low-PRU group), and 15.1% in the high-PRU group (p=0.016 vs. medium-PRU group). At multivariate analysis, a pre-PCI PRU value in the low- or high-PRU group was an independent predictor of increased occurrence of NACE at 30 days. Conclusions. A therapeutic window in platelet reactivity can be identified using validated thresholds that define a group of patients at lower risk for both thrombotic and bleeding events. Tailoring antiplatelet therapy in order to obtain platelet reactivity levels within this range could result in a net lowering of adverse events after PCI.