Dalteparin as Periprocedure Anticoagulation for Patients on Warfarin and at High Risk of Thrombosis

BACKGROUND: Patients taking warfarin and at high risk for thromboembolic complications have traditionally been hospitalized for two to three days to receive standard treatment with intravenous heparin both prior to and following procedures while their international normalized ratio (INR) is subtherapeutic. OBJECTIVE: To assess the feasibility of protocol implementation for outpatient anticoagulation with low-molecular-weight heparin to eliminate or reduce the length of hospital admission needed solely for anticoagulation. METHODS: Patients included were receiving warfarin for a prosthetic heart valve, mitral valve disease with atrial fibrillation, or recent episode of venous thromboembolism. Warfarin was discontinued four days prior to the procedure. Subcutaneous dalteparin 200 units/kg was given on the two mornings prior to the procedure and restarted 12-24 hours after the procedure until the INR was in the therapeutic range. Warfarin was reinitiated on the evening of surgery. RESULTS: Twenty-four patients underwent 26 procedures. There were two minor bleeding complications, and one patient experienced a transient ischemic attack. Patients received a median of five days of dalteparin. The INR returned to the therapeutic range on the median postoperative day 4. All patients avoided two days of hospitalization prior to the procedure (i.e., no patients needed to be admitted preoperatively for anticoagulation). A median of four days would have been required for the sole purpose of postoperative anticoagulation. CONCLUSIONS: Outpatient perioperative anticoagulation with dalteparin for high-risk patients requiring long-term oral anticoagulation appears feasible and warrants further study.