Fibrinogen and Prothrombin Complex Concentrate: The Importance of the Temporal Sequence—A Post-Hoc Analysis of Two Randomized Controlled Trials

<b>Background/Objectives</b>: A low level of soluble coagulation factors after cardiac surgery may cause excessive bleeding and trigger clinical correction using prothrombin complex concentrate (PCC). According to the current guidelines, the trigger values for PCC administration are not defined. In the published algorithms, when driven by ROTEM^®, the triggers vary from 80 s to >100 s of coagulation time (CT) during an EXTEM test. Two randomized controlled trials on fibrinogen (FC) supplementation after cardiac surgery previously pointed out that the patients receiving FC supplementation had a significant decrease in their EXTEM CT. This study investigates the hypothesis that after increasing the availability of a substrate (fibrinogen), thrombin generation induces fibrin network formation faster, and that, before considering PCC administration, the normalization of fibrinogen levels should be sought. <b>Methods</b>: A retrospective study based on a post-hoc analysis of the data collected in two previous RCTs involving 85 patients, all of whom received FC supplementation. <b>Results</b>: The results of this post-hoc analysis demonstrate that there is a significant negative association between FIBTEM maximum clot firmness (MCF) and the EXTEM CTs before and after FC supplementation; FC supplementation decreases the EXTEM CTs both in patients with a low FIBTEM MCF and a normal FIBTEM MCF. After FC supplementation, 45 (53%) of the patients had an EXTEM CT of >80 s, 22 (26%) had an EXTEM CT of >90 s, and 8 (9%) had an EXTEM CT of >100 s. <b>Conclusions:</b> Our study confirms and quantifies the effects of reducing EXTEM CTs through FC supplementation. A stepwise strategy of factors correction with FC supplementation should be used before considering PCC administration as it might reduce the need for PCC.