Effects of Preoperative Vitamin K On the INR in Bridging Therapy

We investigated whether routine incorporation of oral Vitamin K three days before surgery would improve perioperative management.

Patients on chronic warfarin therapy requiring perioperative bridging therapy were the participants in this observational study. Results from two bridging protocols, 30 cases each, with and without oral Vitamin K, were analyzed. Day of Surgery was considered Day 0. The first cohort (control arm) only received oral Vitamin K preoperatively if their INR was >1.5 on Day -1. The intervention cohort (Vitamin K group) routinely received 2.5mg of oral Vitamin K on Day -3. Primary outcome was INR on Day -1. Secondary outcomes were number of patients with INRs ≥1.5 on Day -1 or Day 0, number of surgeries delayed, number of postoperative bleeding or thrombotic incidents and INR on Day 4. Results: On Day -1, the INR for the Vitamin K group was 1.16, compared with 1.28 for the control group (p=0.037). On re-bridging, Day 4 INR was similar in the two groups; 1.37 in the Vitamin K group, and 1.35 in the control group but there was an increase in the dose needed to achieve these levels for the Vitamin K group (24.2% over usual dose for the Vitamin K group vs 7.2% for the control). Only the control group had patients with INRs ≥1.5 on Day -1 (n=5), INRs ≥1.5 on Day 0 (n=2), or had postoperative bleeding incidents (n=2). Neither group had delayed surgeries or postoperative thrombosis.

Adding Vitamin K on Day -3 into bridging protocols leads to a safe preoperative INR and may limit other complications, but this may come at the expense of increased dosing requirements postoperatively.

No relevant conflicts of interest to declare.