Objectives: An increased rate of platelet production is a possible cause of reduced antithrombotic response to once-daily aspirin. Markers of immature platelets (IPs),such as immature platelet count (IPC), immature platelet fraction (IPF), and mean platelet volume (MPV) might be useful for identifying patients who have an increase in their rate of platelet production. However, their potential as markers of platelet production has not been rigorously evaluated. We aimed to investigate the utility of the IPC, IPF, and MPV as surrogates for increased platelet production using coronary artery bypass grafting (CABG) as a model of enhanced thrombopoiesis. Methods: Daily changes in platelet count, IPC, IPF, and MPV were followed in 45 patients undergoing CABG. Results: The rise in IP markers preceded that in the platelet count. IPC (16% per day increase from nadir) but not IPF or MPV showed a significant and sustained rise,which paralleled the pattern observed with platelet count (18% per day increase from nadir).Conclusions: Of the 3 markers, IPC was the most promising as surrogates for platelet production. Future studies should evaluate the utility of the IPC to identify patientswith cardiovascular disease with reduced response to aspirin who might benefit fromtwice-dailyaspirin. Refereed/Peer-reviewed
