To explore the superiority of fibrinogen concentrate (FC) versus cryoprecipitate for bleeding after cardiac surgery.

Secondary analysis of the FIBRES randomized trial.

Eleven Canadian hospitals, February 2017-November 2018.

Adult cardiac surgery patients experiencing significant postbypass bleeding and acquired hypofibrinogenemia (fibrinogen <2.0 g/L or FIBTEM A10 <10 mm).

FC (4 g) or cryoprecipitate (10 units) dosed within 24 hours after cardiopulmonary bypass as needed.

In total, 735 patients (372 FC, 363 cryoprecipitate) were included in the primary analysis (median age 64 years, 30% women). The primary endpoint was cumulative blood components (red cells, platelets, plasma) administered within 24 hours postbypass. Superiority was assessed using deviance-scaled Poisson regression. FC was superior to cryoprecipitate in the a priori‒defined, well-balanced subgroups of non-critically ill patients (n = 634, 86% of population; mean 13.6 versus 16.2 units, mean ratio 0.84 [95% CI 0.73, 0.96]; p = 0.01) and elective surgery patients (n = 466, 63% of population; 11.7 versus 14.4 units, 0.81 [0.69, 0.96]; p = 0.02). In elective surgery patients, adverse events (relative risk 0.85 [0.75, 0.97]; p = 0.02) and serious adverse events (0.71 [0.52, 0.99]; p = 0.04) were less frequent with FC.

FC showed superior hemostatic efficacy to cryoprecipitate in the prespecified subgroups of elective cardiac surgery patients and patients who were not in a critical state before surgery, representing the large majority of patients with bleeding postbypass. FC may also offer safety advantages over cryoprecipitate.