THE QUANTRA PCS, PLATELET CONTRIBUTION TO CLOT STIFFNESS, PARAMETER IS CLINICALLY USEFUL TO IDENTIFY PLATELET-DEPENDENT BLEEDING IN HIGH-RISK CARDIAC SURGERY PATIENTS

Abstract

<h3>Objective</h3> Postoperative use of platelet function testing in order to rule out microvascular bleeding due to platelet dysfunction after cardiac surgery still lacks strong reference data and reliable cut-off values. We investigated the performance of two different point-of-care viscoelastic devices and platelet aggregometry in expressing surgery-dependent platelet dysfunction and anticipating postoperative major bleeding in a cohort of high-risk patients. <h3>Design and Method</h3> This is a prospective cohort study on 50 adult patients who underwent cardiac surgery with cardiopulmonary bypass (CPB) being on antiplatelet drugs discontinued for no more than 7 days (clopidogrel, prasugrel) or 5 days (ticagrelor). Coagulation and platelet function testing, including QUANTRA, ROTEM and Multiplate were assessed preoperatively and postoperatively. Chest drain blood loss was measured in the first 12 postoperative hours. Perioperative bleeding was assessed using the Universal Definition of Perioperative Bleeding (UDPB) in cardiac surgery, modified to not consider anemia-correcting packed red cells transfusions in absence of bleeding > 600 ml/12 h. Major bleeding was identified as UDPB class II or higher. <h3>Results</h3> The QUANTRA Platelet contribution to Clot Stiffness (PCS) was significantly (P=0.001) reduced after CPB. Multiplate ADPtest was significantly (P=0.001) reduced, as well, whereas TRAPtest was not. The platelet component (PC) as extrapolated by ROTEM data (EXTEM MCF – FIBTEM MCF) was unchanged after CPB, while the A10 PC (PC at 10 minutes) significantly (P=0.001) decreased. At regression analysis of the preoperative and postoperative platelet function parameters, there was a significant linear correlation (P=0.001) for the PCS, A10 PC and ADPtest. At the ROC analysis for the predictive ability of the post-CPB platelet function testing, the best discrimination was obtained by the QUANTRA PCS, with an AUC of 0.788, followed by the ROTEM A10 PC (AUC 0.765) and PC (AUC 0.758). The Multiplate tests did not achieve an AUC > 0.70. The cut off values identified for the QUANTRA PCS (10.5 hPa), the ROTEM A10 PC (38 mm) and for the ROTEM PC (47 mm) yielded a combination of a negative predictive value > 80% and a positive predictive value > 67%. <h3>Conclusions</h3> QUANTRA PCS, ROTEM A10 PC, and Multiplate ADPtest reflect the post-CPB platelet dysfunction, whereas ROTEM PC and Multiplate TRAPtest do not. Major bleeding was predicted with a moderate degree of discrimination by the post-CPB viscoelastic tests (PCS, PC, A10 PC) but not by the Multiplate tests.