Clinical, echocardiographic, and pathologic characteristics of patients with pathology-proven nonbacterial thrombotic endocarditis

Background Non-bacterial thrombotic endocarditis (NBTE) is a non-infectious condition characterized by thrombotic and/or inflammatory depositions involving the cardiac valves. It is a challenging diagnosis of exclusion. Purpose This study aimed to better characterize patients with pathologically proven NBTE and assess its clinical, echocardiographic characteristics and prognostic implications. Methods We retrospectively identified patients with pathology-proven NBTE at a single center. Patients with positive preoperative blood cultures, a history of active or treated infective endocarditis, or identification of valvular organisms by special stains were excluded from the study. Patients with pathology reports of valve perforation or chordal rupture were also excluded because of the high likelihood of an infectious etiology for these lesions. Results A total of 53 patients with NBTE (median age 57 years; 61% females) were identified. In this cohort, 22% had a history of malignancy, 30% had connective tissue disease, 32% had coronary artery disease, and 11% prior history of NBTE. Neurological events accounted for 18 (34%) of the presenting symptoms (TIA n=17, CVA n=9), while new valvular dysfunction in 7 (13%) and fever in 8 (15%) of patients. Five patients (9%) had NBTE involving more than one valve. NBTE involved the mitral valve in 64%, aortic valve in 38% prosthetic/mechanical valve in 11%, and tricuspid valve in 5%. NBTE was identified at the time of autopsy in 34% of patients. NBTE recurred in 3 patients during follow-up. Excluding patients diagnosed at the time of autopsy, 9% of patients died within 1 year of NBTE diagnosis. Conclusion NBTE was diagnosed pathologically in the presence of hyper-inflammatory states due to critical illness or immunological diseases. It was predominantly on the left side of the heart and was associated with embolic phenomena, either clinically or on imaging. Patients diagnosed with antemortem with NBTE have a high mortality in the first year (9%).