Treatment failure of low molecular weight heparin in a patient with an aortic mechanical prosthesis.

After mechanical heart valve replacement use of unfractionated heparin is sometimes required because vitamin K antagonists are temporarily contraindicated or to prevent valve-associated thromboembolism until oral vitamin K antagonists take effect. Bridging therapy with a standardized low molecular weight heparin-based regimen has been reported effective and relatively safe in a large cohort of patients with mechanical heart valves. Many cases with mitral mechanical valve prostheses and treatment failure of low molecular weight heparin have also been reported as well as prosthetic valve thrombosis has been reported with adequate anticoagulation. A case has also been reported of well functioning Starr-Edwards aortic prosthesis without anticoagulation. We present a case of cardioembolic stroke in a patient with an aortic mechanical prosthesis in bridging therapy with a standardized low molecular weight heparin-based regimen. This case is illustrative of treatment failure of low molecular weight heparin in a patient with an aortic mechanical prosthesis.