Randomized, placebo-controlled trial of orally administered vitamin K1 for warfarin-associated coagulopathy in Chinese patients with mechanical heart valves.

PURPOSE: Warfarin-associated coagulopathy commonly occurs in patients undergoing treatment with this anticoagulant. This trial aimed to determine the efficacy of using low-dose orally administered vitamin K1 to lower international normalized ratio (INR) values into the target range in a cohort of Chinese patients with mechanical heart valves. METHODS: This was a double-blind, placebo-controlled, randomized trial. Chinese patients with mechanical heart valves who were undergoing warfarin treatment and who had INR values from 4.0 to 10.0 without bleeding were the subjects of this study. These patients were randomized into two treatment groups and were orally administered either vitamin K1 (2.5 mg) or placebo. Warfarin was discontinued in both groups until INR values were ≤ 2.5. INR values on the day following treatment were the primary study outcome, with INR values on the following days and adverse clinical events over a 3-month follow-up serving as secondary study outcomes. RESULTS: In total, 80 patients were enrolled in the present study, and 40 patients each were assigned to the placebo and vitamin K1 treatment groups. Patients administered vitamin K1 exhibited a quick reduction in INR values relative to patients administered placebo (29 of 40 [72.5%] vs. 0 of 44 [0%] patients exhibiting INR values from 1.5-2.5 on the day following treatment, respectively, p = 0.000). Lower bleeding incidence was observed among patients administered vitamin K1 relative to those administered placebo during follow-up (4 [10%] vs. 12 [30%] patients, respectively, p = 0.045). There were no instances of thromboembolic complications or warfarin resistance in either group. CONCLUSION: Low-dose oral vitamin K1 can be effectively administered to Chinese patients with mechanical heart valves taking warfarin to rapidly reduce elevated INR values.