Purpose: The aim of this study was to confirm that emergency platelet transfusion effectively restores platelet function to patients receiving antiplatelet therapy (APT) with aspirin and/or clopidogrel.
Patients and methods: This was a prospective observational case report series conducted between January 1, 2009, and January 1, 2012. All responder patients according to the Verify Now device requiring emergency platelet transfusion because of a potentially life-threatening hemorrhage or before emergency neurosurgery were included. Aspirin or P2Y12-specific tests were used as appropriate for patients under aspirin or clopidogrel. Patients who were responders to aspirin had an aspirin reaction unit of less than 550, and patients who were responders to clopidogrel had an inhibition percentage of more than 20%. The Verify Now test was performed again after platelet transfusion. Pretransfusion and posttransfusion test results were compared.
Results: During the 36-month period, 25 patients met the inclusion criteria. Of these patients, 4 were receiving dual APT, 8 were receiving clopidogrel only, and 13 were receiving aspirin only. The average platelet transfusion dose was 0.12 UI/kg (range, 0.10-0.14 UI/kg). For patients under clopidogrel, the inhibition percentage lowered significantly after transfusion (median 54 [range, 31-69] before and 25 [range, 18-50] after transfusion; p < 0.005) but remained above the 20% threshold. Our patients were still responsive to clopidogrel after platelet transfusion. This result is conflicting with the existing literature. The median aspirin reaction unit of aspirin users before and after transfusion were 420 (range, 400-470) and 630 (range, 610-640), respectively (p = 0.001). The efficacy of platelet transfusion to restore aspirin-mediated disaggregation is confirmed by our case series.
Conclusion: Platelet transfusion does not restore platelet function in patients under clopidogrel, but it is efficient for patients under aspirin. This sheds new light on previous large-scale studies that have been unable to show any effectiveness of emergency platelet transfusion in patients under APT. Emergency platelet transfusion may only be indicated in aspirin users who are responders and not in all patients under APT as is actually recommended.