VerifyNow® Tests Procedure The study protocol included measurements of platelet reactivity using a VerifyNow Tests Procedure (Accumetrics Inc., USA). This method detects platelet activity by measurement of platelet aggregation, in a blood sample, exposed to a specific agonist. This leads to an inhibition of platelet function in response to anti-platelet therapy. The VerifyNow System is a whole blood device that performs qualitative measurement of induced platelet aggregation based on the increase in light transmittance. Two types of VerifyNow test kits were used in the study: VerifyNow Aspirin Test and VerifyNow P2Y12. The Aspirin test results are reported as Aspirin Reaction Units (ARU), which are calculated as a function of the rate of aggregation. ARU values less than 550 indicate effective result of ASA, while values > 550 ARU indicate no effect of the drug. The VerifyNow P2Y12 test measures platelet function based on the ability of activated platelets to bind fibrinogen and provides information on the aggravation of platelet aggregation in reactivity units of P2Y12 receptor (PRU). It is considered that the range of 95 - 208 PRU is responsible for optimal antiplatelet activity. High PRU values after drug administration, point to the lack of expected anti-platelet effect.