Measurement of platelet reactivity in thrombocytopenic patients on dual antiplatelet therapy after percutaneous coronary intervention.

BACKGROUND Thrombocytopenia remains a significant problem in patients with cardiovascular disease (CVD) due to the indispensable use of antiplatelet therapy.

OBJECTIVES The aim of this study was to establish a novel flow cytometry (FC)-based method for measuring platelet reactivity during dual antiplatelet therapy (DAPT) and to compare it with impedance aggregometry (IA) in thrombocytopenic patients undergoing percutaneous coronary intervention (PCI).

MATERIAL AND METHODS This prospective cross-sectional study included 30 patients with thrombocytopenia. Platelet aggregation was assessed using IA and FC.

RESULTS A similar response to arachidonic acid (AA), reflecting the effect of acetylsalicylic acid (ASA), was observed in both groups. Responses to thrombin receptor agonist peptide (TRAP) and adenosine diphosphate (ADP), measured with aggregometry, were significantly higher in thrombocytopenic patients than in patients with normal platelet counts. When the FC method was used, the response to AA was significantly higher in thrombocytopenic patients. The optimal cut-off value for the FC method to define adequate platelet reactivity inhibition with clopidogrel in thrombocytopenic patients was <25.7%.

CONCLUSIONS In patients with thrombocytopenia, IA is useful for assessing ASA response, whereas the presented FC method may be more accurate for evaluating response to clopidogrel.