Nonbacterial Thrombotic Endocarditis in a Patient With Influenza

Abstract

Introduction: Nonbacterial thrombotic endocarditis (NBTE) is characterized by vegetations on cardiac valves in the absence of pathologic evidence of inflammation or bacteria. CASE PRESENTATION: A 47 year old female presented with dyspnea and bilateral infiltrates on chest imaging and was treated for community acquired pneumonia. Her respiratory failure progressed and she required intubation and transfer to the ICU for worsening ARDS. She subsequently tested positive for 2009 H1N1 influenza. She required sedation and paralysis to optimize oxygenation. Initial echocardiogram suggested presence of a vegetation on the mitral valve with severe mitral regurgitation which was confirmed with transesophageal echocardiogram. All blood cultures remained negative. Five days into her ICU stay she developed ischemic changes of the hands, feet, and nose, consistent with systemic embolization. Upon discontinuing paralytics she remained comatose with absent motor responses. A head CT showed new extensive bilateral acute and subacute infarctions involving the cerebrum, cerebellum, and thalamus. After discussion with family the decision was made to pursue comfort measures. An autopsy was performed which confirmed nonbacterial thrombotic endocarditis involving the mitral and tricuspid valves, as well as diffuse alveolar damage pattern in the lungs. DISCUSSION: NBTE has been associated most commonly with malignancy but also with disseminated intravascular coagulation (DIC), connective tissue disease, autoimmune disease, and acquired immunodeficiency syndrome. Histologically, the vegetations in NBTE consist of a collection of platelets and fibrin with an absence of inflammatory cells or organisms. These vegetations tend to be small, friable, and are prone to embolization. Recommendations for treatment include systemic anticoagulation and possibly surgery if recurrent embolization occurs despite anticoagulation. In this case the patient presented with evidence of NBTE in the absence of malignancy, DIC, or other known triggers. Use of paralytics for severe ARDS probably led to a delayed diagnosis of CNS embolic disease. Conclusions: This is the first case in the literature documenting NBTE in association with influenza infection. NBTE should be considered in the differential diagnosis of patients with viral infections such as influenza and evidence of endocarditis.