Comparison of different methods to evaluate the effect of aspirin on platelet function in high-risk patients with ischemic heart disease receiving dual antiplatelet treatment

Patients with coronary artery disease (CAD) receiving aspirin therapy with a residual platelet reactivity (RPR) may be at increased risk of ischemic vascular events. Point-of-care (POC) methods PFA-100 (Dade-Behring, Marburg, Germany) and Verify Now (Accumetrics, San Diego, CA) assays have been suggested as rapid tools to evaluate RPR. We compared PFA-100 closure times by collagenlepinephrine and Verify Now Aspirin assays with light transmission aggregation (LTA) induced by 1 mmol/L of arachidonic acid in 484 patients with CAD undergoing percutaneous coronary intervention and receiving dual antiplatelet therapy. RPR was detected in 30.0% of patients by LTA, in 32.4% by PFA-100, and in 14.3% by VerifyNow. Significant correlations were found among 3 methods (all P <.0001). In relation to the presence or absence of RPR by LTA and PFA -100, by LTA and VerifyNow, and by PFA -100 and VerifyNow, samples were significantly concordant (all P <. 0001). Assuming LTA as the reference method, PFA-100 and VerifyNow showed sensitivity of 62. 1 % and 39.3 % and specificity of 80.2% and 964%, respectively. The cutoff valuesfor POC methods need to be definedfor clinical use.