Changes in circulating cell populations may promote ischemic events that occur soon after discontinuation of P2Y12-inhibition. The aim of the study was to track the course of thrombopoietic and erythropoietic cells in patients with coronary artery diseases (CAD) after planned and physician-driven cessation of chronic P2Y12-inhibition (clopidogrel 75 mg OD, or prasugrel 10 mg OD, or ticagrelor 90 mg BID). Cell fractions were determined in 62 patients at baseline (the last day of P2Y12-inhibitor intake), on day-10, day-30, and day-180 thereafter. Immature platelet fraction (IPF), immature reticulocyte fraction (IRF), reticulocyte hemoglobin content (Ret-Hb) and red blood cell count (RBC) significantly increased from baseline to day-180 (IPF: p = .003; IRF: p = .013; Ret-Hb: p < .001; RBC: p = .044). Platelet count, leucocyte count and immature granulocyte fraction did not change over time (p = .561, p = .869, and p = .161, respectively). Fibrinogen levels significantly declined over time (p = .011), thrombopoietin levels increased in a non-significant manner (p = .379). We did not observe any significant interaction with choice of P2Y12-inhibitor, therefore suggesting a drug class-effect. Our data shows, that discontinuation of dual antiplatelet therapy is associated with raised thrombopoietic and erythropoietic activity in the bone marrow, without significant upregulation of thrombopoietin. This provides further evidence for a direct stimulation of precursor cells by P2Y12-inhibitors.
