Recurrent native and prosthetic mitral valve thrombosis in idiopathic hypereosinophilic syndrome

Hypereosinophilic syndrome (HES) is defined as a prolonged, unexplained peripheral eosinophilia. Endomyocardial fibrosis and mural thrombus formation are common occurrences such that patients are exposed to lethal thromboembolic complications. The valvular damage described is mainly related to iterative valve thromboses that are amenable to surgery. Here, the case is reported of a 39-year-old woman suffering from HES with mitral valve thrombosis and mechanical prosthetic mitral valve replacement, in whom a new thrombosis of the inserted prosthesis occurred one month postoperatively, concomitant with severe hypereosinophilia and despite adequate anticoagulation. The patient had received a new bioprosthetic mitral valve replacement, and her eosinophil count had been normalized after treatment with corticosteroids. Oral anticoagulation with warfarin was maintained. Subsequently, no recurrent thromboembolic events were reported, and echocardiography performed at the one-year follow up showed the bioprosthesis to have a normal hemodynamic profile.