Aspirin non-responsiveness in Korean subjects on dual anti-platelet treatment determined by two different platelet function assays.

Several techniques are available for measuring platelet function during aspirin therapy, but none is well standardized, and the reported incidence of aspirin non-responders varies widely, from 5 to 50%. We evaluated the optical platelet aggregation test and the Platelet Function Analyzer-100 test (PFA-100) for assessing aspirin responsiveness in patients receiving dual anti-platelet therapy, and we measured the incidence of non-responders to aspirin among Koreans. The study enrolled 88 participants including 51 patients on dual anti-platelet therapy, 31 controls, and 6 other volunteers. Optical platelet aggregation in response to 4 agonists and aggregation using the PFA-100 test were determined. In addition, medical records, including the results of platelet aggregation tests, were reviewed for 351 patients receiving aspirin therapy. The results showed good correlation between the PFA-100 test using a collagen/epinephrine cartridge (CEPI) and the optical platelet aggregation test using each agonist. The platelet aggregation test using arachidonic acid revealed marked suppression of aggregation (>98% inhibition) in patients taking aspirin; this value was highly correlated with the PFA-100 results using the CEPI cartridge. Seven of 351 Korean subjects (2.0%) receiving aspirin treatment were non-responsive to aspirin. This study shows that the optical platelet aggregation test using arachidonic acid gave an accurate assessment of the response to aspirin, and that results of the PFA-100 test using the CEPI cartridge correlated well with results of the optical platelet aggregation test.