Reversal of warfarin anticoagulated patients prior to minor invasive procedures can be achieved by traditional warfarin cessation and resumption (WCAR), but also using a small dose of oral vitamin K1 (VK) while continuing warfarin unchanged (VKCW). We compared these methods using a previously described formula to predict the dose of oral VK.
A prospective, randomized, controlled trial to evaluate WCAR and VKCW, in stable outpatients on warfarin prior to elective, minor surgical or dental procedures was performed. Warfarin was withheld for 3 days preprocedure in the WCAR group and oral VK was given 36 hours preprocedure for the VKCW group. Blood samples for prothrombin time International Normalized Ratio (INR) were determined 3-4 days preprocedure, day of procedure, and periodically until INR ≥ 2.0. A linear regression equation described a semilog plot of lnINR as a function of time (days) and used to calculate nadir and return. Values are mean +/− SEM
We enrolled 25 patients for 26 reversals (15 VKCW, 11 WCAR), age 56 years (range 30-82), with various diagnosis: 15 (56%) atrial fibrillation, 7 (26%) deep venous thrombosis, 7 (26%) mechanical valves, 11 (41%) other. Dental procedures were performed on 18 (69%) and minor surgery on 8 (31%) of patients. Weekly warfarin dose was 37 +/− 5 mg for all patients. The oral VK, a scored 5.0 mg tab, was dosed at 3.5 +/− 0.4 mg (range 2.5-5.0 mg). All 26 reversals were successful (INR≤ 1.8), one procedure cancelled (VKCW) for other reasons. Thirty days postprocedure, no thrombotic events or major bleeds occurred in either group and there were no differences in minor bleeds. See Table 1VKCWWCARp valueINR, baseline2.6 +/− 0.22.3 +/− 0.1NSINR, Procedure1.5 +/− 0.11.3 +/− 0.1NSDays to Nadir0.9 +/− 0.21.5 +/− 0.2NSDays to INR ≥ 2.04.3 +/− 0.75.7 +/− 1.80.09Total Days INR < 2.06.2 +/− 0.57.2 +/− 1.60.03below.CONCLUSIONS: Both methods reduced the INR to a safe level to perform minor invasive procedures without significant complications. VKCW may reduce the period of subtherapeutic anticoagulation.
VKCW, when using an adjusted dose of oral VK, may be a safe alternative method to reverse stable anticoagulated patients prior to minor invasive procedures.
T.H. Wentzien, DuPont Co., grant monies.