Oral anticoagulation throughout pregnancy in patients with mechanical heart valve prosthesis: Safe alternatives

Abstract

Small dose of Warfarin (⩽5 mg/day) was suggested as being safe in pregnant patients with mechanical heart valve prosthesis (MHVP) however; no other oral anticoagulant (OA) alternative has been proposed to cases failing to achieve their target INR. We aimed to suggest the alternative use/shift of those cases to our previously reported safe (OA) Phenindione (⩽100 mg/day) and to compare both regimens. Eighty-seven females with 106 bileaflet MHVP implanted in the aortic (10; 11.5%), mitral (58; 66.7%) or both positions (19; 21.8%) continued OA throughout pregnancy, with restriction of daily doses to 5 mg Warfarin or 100 mg Phenindione. Patients were allowed to cross over if failed to achieve their target INR: 2-3.5. Aspirin (100 mg/day) was supplemented, starting second trimester. Out of 59 patients initially receiving Warfarin, 15 (25.4%) shifted to Phenindione, compared to none of 28 patients originally receiving Phenindione (P = 0.002). Mean INR and daily OA dose for 44 patients remaining on Warfarin and 43 patients receiving Phenindione were: 2.39 ± 0.34 versus 2.25 ± 0.2 (P > 0.05) and 3.9 ± 1.07 mg versus 79.3 ± 18.5 mg; respectively. Maternal complications were six cases of resolved vaginal bleeding (6.9%). There were no cases of embryopathy or prematurity. Fetal outcomes included 68 live births (78.2%), seven abortions (8%), two fetal loss (2.3%); all insignificantly related to OA dose or INR level. Although ⩽5 mg Warfarin per day can be safe during pregnancy, yet it cannot always achieve the target INR and ⩽100 mg of Phenindione can be considered as a comparatively safe alternative.