Short‐term warfarin reversal for elective surgery – using low‐dose intravenous vitamin K: safe, reliable and convenient*

Peri-procedural management of warfarin reflects an intricate balance between the restoration of haemostasis and appropriate thromboprophylaxis. This prospective single-arm study assessed the safety and efficacy of a convenient schedule, incorporating low-dose intravenous vitamin K (vitK(IV) ) for short-term warfarin reversal prior to elective surgery, as well as vitK-dependent factor levels (vitK-Factors) and International Normalized Ratio (INR) pre- and post-vitK(IV) . One seventy eight patients on long-term warfarin received 3mg vitK(IV) 12-18 h pre-procedure with no adverse reactions. 167/178 (94%) achieved an INR≤1·5 post-vitK(IV) on the day of surgery, while all achieved INR≤1·7. Four patients had procedure-associated major bleeding, but importantly had achieved a pre-procedure INR<1·5 and vitK-Factors >0·30iu/ml. No patient suffered a symptomatic thromboembolism during the 6-week follow-up. Median days to re-establish a therapeutic INR were 4 (range 2-11). VitK(IV) near normalized all vitK-Factors, with a uniform pattern of depletion and repletion in association with an increase and decrease in INR, respectively; and from the data, INR<1·5 correlated with vitK-Factors >0·30iu/ml. Low-dose vitK(IV) for short-term warfarin reversal was reliable and safe, and successfully lowered the INR to an acceptable level for planned surgery, with no excess of bleeding, thromboembolism, delayed discharge, or resistance to warfarin. The protocol was simple and convenient for both the patients and the healthcare institution.