Postoperative dalteparin bridging did not prevent major thromboembolisms or bleeding events among patients with atrial fibrillation or mechanical heart valves. These findings from a prospective, double-blind, randomized controlled trial were published in The BMJ.

Patients (N=1471) with atrial fibrillation or mechanical heart valves who needed to interrupt warfarin due to a surgical procedure were recruited at 10 sites in Canada and India between 2007 and 2016 for the PERIOP2 trial. All patients stopped warfarin use 5 days prior to surgery and were given 200 IU/kg dalteparin 72 and48 hours before surgery and 100 IU/kg 24 hours before surgery. Patients were randomly assigned to receive daily dalteparin (n=821) or placebo (n=650) for at least 4 days following their procedure. Clinical outcomes through 90 days were assessed.

Patients had a mean age of 69.7 (SD, 12.3) years, 64.3% were men, 79.3% had atrial fibrillation only, 20.7% had mechanical valves, and 80.4% had hypertension.

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Among the intervention cohort, patients with low risk for bleeding (n=287) received a mean dose of 15,256 IU and the patients at high risk (n=520) received a dose of 5024 IU dalteparin.

At 90 days, major thromboembolisms occurred among 1.0% of dalteparin and 1.2% of placebo recipients (risk difference, -0.3%; 95% CI, -1.3% to 0.8%; P =.64) and major bleeding events among 1.3% and 2.0% (risk difference, -0.7%; 95% CI, -2.0% to 0.7%; P =.32), respectively. Similar results were observed for the composite endpoint of major thromboembolism and bleeding events (risk difference, -0.9%; 95% CI, -2.6% to 0.8%; P =.28).

This study was limited by an error in randomization at 2 sites that caused all patients with atrial fibrillation who had low risk for bleeding to be assigned to the dalteparin intervention group. The imbalance was corrected at 2 other sites in which similar patients were randomly assigned in a 1:4 ratio to receive the dalteparin or placebo.

This study did not identify a benefit from dalteparin bridging among patients with atrial fibrillation or mechanical heart valves interrupting warfarin due to surgical intervention.

Disclosure: Pfizer supplied the study drug. Please see the original reference for a full list of disclosures.


Kovacs MJ, Wells PS, Anderson DR, et al; PERIOP2 Investigators. Postoperative low molecular weight heparin bridging treatment for patients at high risk of arterial thromboembolism (PERIOP2): double blind randomised controlled trial. BMJ. 2021;373:n1205. doi:10.1136/bmj.n1205