Successful Anticoagulation with Dalteparin in a Patient with Mechanical Heart Valves

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Abstract
BACKGROUND: Standard thromboprophylaxis of patients with mechanical heart valves is achieved using warfarin. In certain patients this may be very difficult; thus, alternative pharmacotherapy must be used. OBJECTIVE: To report a case of a patient who successfully used dalteparin, a low-molecular-weight heparin, for anticoagulation. CASE SUMMARY: A 58-year-old white woman with mechanical aortic and mitral heart valves initially received warfarin for anticoagulation. Thromboprophylaxis was very challenging. Her international normalized ratios (INRs) were erratic and occasionally responded paradoxically to changes in dose. Finally, she experienced a left hemispheric stroke when her INR was extremely subtherapeutic. Subsequently, despite best efforts, her INR again was subtherapeutic; warfarin was discontinued and dalteparin was initiated with daily self-administered subcutaneous injections of 16 000 units. No complications have arisen since initiation of the new pharmacotherapy approximately 18 months ago. DISCUSSION: The use of low-molecular-weight heparin for the treatment and prevention of venous thromboembolism is well described. There are few reports of its use for thromboprophylaxis of patients with mechanical heart valves. Our patient has been managed successfully with dalteparin. CONCLUSIONS: Dalteparin was effectively and safely used for the thromboprophylaxis of a patient with mechanical heart valves whose anticoagulation was previously difficult to manage with warfarin. Dalteparin deserves further study in patients who are unable to tolerate warfarin.