Coagulopathy, bleeding, and transfusion of allogeneic blood products remain major concerns in a relevant portion of patients undergoing cardiac surgery, and all of them have been associated with increased postoperative morbidity and mortality.^1,2 Prothrombin complex concentrate (PCC) has received increasing recognition in the perioperative treatment of bleeding patients after cardiac surgery. The recent Factor Replacement in Surgery (FARES) II trial randomized 528 patients who developed bleeding due to coagulation factor deficiency after cardiopulmonary bypass (CPB) to receive either PCC at a dose of 1,500 to 2,000 units or 3 to 4 units of fresh frozen plasma (FFP) after heparin reversal.³ This trial found that treatment with FFP was associated with better hemostatic efficacy (78% vs. 60% of patients; p < 0.001) and lower need for transfusion with allogeneic blood products including red blood cells, platelets, and noninvestigational FFP as compared with primary treatment with FFP. In addition, safety advantages favoring PCC were reported.³ However, the qualitative and quantitative definition of coagulation factor deficiency after CPB is commonly difficult to determine. The use of viscoelastic coagulation testing (VET), including thromboelastometry/graphy or sonorheometry, has been suggested in several guidelines to limit postoperative coagulopathy and bleeding after cardiac surgery.^2,4,5 Whereas it has been shown that VET parameters allows for an excellent estimation of fibrinogen levels and, at least partially, of platelet count,^6–8 it is less clear whether dosing of PCC can be reliably guided by thromboelastometric parameters.

In this issue of the Journal of Cardiothoracic and Vascular Anesthesia, Vander Zwaag et al⁹ report their findings from a retrospective single-center study in 175 patients undergoing cardiac surgery. The primary outcome was the change of clotting time (CT) in EXTEM before and after therapy with PCC at a median dose of 3,000 units. The first measurement was performed after aortic declamping but before CPB weaning and heparin reversal. The second rotational thromboelastometry (ROTEM) was performed after hemostatic therapy, including PCC administration. Neither the first CT EXTEM in the on-pump ROTEM evaluation nor the second CT EXTEM after hemostatic resuscitation with PCC was predictive of postoperative increased bleeding. The adjusted effect of PCC dosing on CT EXTEM change was modest and statistically not significant. Finally, the authors reported missing predictive value of CT EXTEM for severe postoperative bleeding with an area under the curve of 0.486 in the receiver operating characteristic analysis. However, the authors also stated that a CT EXTEM threshold of greater than 76.5 seconds was optimal for treatment with PCC, however, with low specificity and sensitivity.