Arteriolar vs. valvular thrombosis: Pick your evil!

Anticoagulation therapy for mechanical prosthetic valves is limited to vitamin K antagonists, unfractionated heparin and low-molecular-weight-heparin. Other forms of anticoagulation are either contraindicated or have not been well studied. Hence, anticoagulation for preexisting mechanical valves is controversial if vitamin K antagonists are contraindicated. We present a case involving an end-stage-renal disease patient with both mitral and aortic mechanical valves who developed warfarin-induced calciphylaxis.

A 72-year-old male with history of end-stage renal disease, chronic atrial fibrillation and rheumatic heart disease status post mitral and aortic valve replacements presented with complaints of left thigh erythema with skin induration. Despite multiple antibiotic regimens for presumed cellulitis, the skin lesions progressed to necrotic ulcers. A biopsy revealed evidence of calciphylaxis; a lethal condition typically associated with renal disease. The patient was on warfarin for anticoagulation of his mechanical heart valves as well as prophylactically for atrial fibrillation. Warfarin contributes to the development of calciphylaxis and needed to be exchanged to avoid progression of the ulceration. The only other acceptable option for long-term anticoagulation was subcutaneous unfractionated heparin but this approach was not taken. The patient suffered from further sequelae of calciphylaxis and eventually expired.

Calciphylaxis is a rare, serious disorder that presents with skin ischemia and necrosis mainly in end-stage renal disease patients. The pathogenesis and treatment are poorly understood and the prognosis remains grave. It is proposed that certain medications, including warfarin, contribute to its evolution. The optimal anticoagulation therapy in those with concomitant warfarin-induced calciphylaxis and mechanical valves is undetermined. Further studies are essential to establish new anticoagulation regimens in these devastating circumstances.