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Dynamic Responsiveness to Aspirin in Patients Undergoing PCI
Abstract number: P1094
Varon1 D, Brill1 A, Abdelrahman2 N, Touretsky1 N, Mosseri1 E, Lotan1 H, Pugatch1 T, Mosseri1 M
11Hebrew University Hadassah Medical Center, Jerusalem, Israel 11Hebrew University Hadassah Medical Center, Jerusalem, Israel 22Bikur Holim Hospital, Jerusalem, Israel
Recently, a vast variability has been reported in the response to anti-platelet agents. We evaluated short and long term responses to Aspirin in patients undergoing PCI and stenting. Eighty seven consecutive patients were included (60 unstable angina, 18 acute MI and 9 stable angina). All were on aspirin 100 mg before and received Clopidogrel immediately after PCI for 4 weeks. Platelet function was tested before, and 1 and 180 days after PCI. Optical aggregometry was performed using arachidonic acid (AA) as an agonist (in response to Aspirin maximal aggregation is <25%). Impact – Cone and Plate(let) Analyzer test was performed in the presence of AA (in response to Aspirin surface covered (SC) by adhered platelets is >2.5%). Results: | Test | Day 1 | Day 2* | Day 180* |
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| Average response | % non responders | Average response | % non responders | Average response | % non responders |
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| AA-induced aggregation | 33.3% | 60% | 10% | 25% | 15% | 25% | | Impact with AA (SC) | 1.8% | 80% | 4.1% | 22% | 5.2% | 10% | | * P < 0.05 compared to day 1. |
Seven of 8 patients who needed additional PCI during a 6 month follow up were unresponsive to Aspirin on day 1 according to both assays. In conclusion, high rate of unresponsiveness to Aspirin upon admission for PCI is observed among patients with ACS. At one day after PCI and loading dose of 300 mg Clopidogrel, there is a significant shift toward responsiveness to aspirin which is maintained 6 months later while on Aspirin only. Unresponsiveness to aspirin on admission conferred a higher risk (odds ratio 2.8) for an additional PCI during the following 6 months.
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