(PC116) Characterizing the Effect of Heparin Dose and Monitoring Activated Clotting Time on Postoperative Lower Extremity Bypass Outcomes

Objectives: Intraoperative anticoagulation is essential for safe vascular occlusive control. Intravenous heparin is most commonly administered at a dose targeted to a measured intraoperative activated clotting time (ACT) of >250 seconds. The effects of heparin dosing or monitoring ACT on postoperative outcomes remains poorly characterized.

Methods: Using data from a statewide quality improvement collaborative, we investigated rates of postoperative bleeding, arterial/graft thrombosis, major amputation, readmission and death among patients within 30 days after lower extremity bypass (LEB). We adjusted for patient clinical and sociodemographic factors, as well as procedural factors. In addition to descriptive statistics, we used a Bayesian random effects logistic regression model with non-informative prior to investigate the effect of heparin dosing, ACT monitoring, as well as an interaction effect between the two.

Results: A total of 9,030 patients undergoing LEB from 34 hospitals were included, among whom 190 (2.1%) experienced arterial/graft thrombosis, 152 (1.7%) post-operative bleeding, 824 (9.1%) 30-day amputation, 1,029 (11.4%) 30-day readmission, and 42 (0.5%) 30-day mortality. Rates of ACT monitoring varied substantially across hospitals (12%-100%) with 4290 (47.5%) of patients having ACT monitored intraoperatively. Heparin doses were slightly higher among patients in whom ACT was monitored, but neither heparin-dose nor ACT monitoring were associated with post-operative thrombosis or bleeding (Figure 1). Intraoperative administration of protamine was associated with reduced post-operative bleeding (OR 0.28, 95% Credible Interval 0.17-0.46).

Conclusions: There exists substantial variation in intraoperative heparin dose and monitoring of ACT across hospitals, but this variation is not associated with differences in post-operative outcomes. Future randomized studies targeting standardized intraoperative heparin dosing and ACT monitoring protocols may result in simplified care pathways without negatively affecting outcomes.