Safety of prothrombin complex concentrate for emergency surgery according to the oral factor Xa inhibitor level

Background Anti Xa assays are seldom rapidly available, prompting clinicians to frequently administer 4-factor-prothrombin complex concentrate (4F-PCC) empirically. Objective Determine if the thrombotic risk increases when pre operative factor Xa inhibitor (XaI) levels are low or unmeasured. Methods We analyzed retrospectively all patients that received 4F-PCC between September 2018 and July 2024 at 5 hospitals in the Hamilton region and screened for those with emergency surgery/invasive procedure as main indication. The primary outcomes were symptomatic or asymptomatic, objectively verified arterial or venous thromboembolism within 7 days from PCC infusion. The secondary outcome was the same between postoperative day 8 and 30. XaI levels were determined with an anti-Xa assay, calibrated with the respective oral anticoagulant used by the patient. Results PCC at a median dose of 2000 units (interquartile range, 2000-2000) was administered to 227 patients on apixaban (143; 63%), rivaroxaban (72; 32%), or edoxaban (12;5%). Mean age was 76 years and 42% were female. Prophylaxis against venous thromboembolism was started promptly in 214 patients (94%) after a median of 1 day (interquartile range, 1-2). Thromboembolism within 7 days occurred in 1 of 38 patients (3%) with high XaI level, 0 of 24 with low level and 9 of 165 (5%) with no level. Conclusion The risk of thromboembolism after 4F-PCC in patients on XaI and emergency surgery/invasive procedures appears to be similar among patients with preoperative XaI levels that are high, low or not measured. This information might be helpful in settings where rapid anti Xa testing is unavailable.