High prevalence of embolic complications among cancer patients with non-bacterial thrombotic endocarditis

Background Cancer is a major cause of nonbacterial thrombotic endocarditis (NBTE), an underdiagnosed condition characterized by sterile valvular vegetations. NBTE is associated with a high risk of arterial thromboembolism and represents an important cause of cancer-associated stroke. However, clinical data on NBTE and its embolic complications remain limited. Methods In this retrospective cohort study, we analyzed clinical data from all patients with endocarditis and active malignancy who were assessed at our tertiary care center between January 2019 and July 2025. Based on clinical course, blood culture results, laboratory markers of infection, and vegetation morphology on transesophageal echocardiography, patients were retrospectively classified with regard to suspected NBTE. Results Among 112 patients with endocarditis and active malignancy, 19 were retrospectively diagnosed with NBTE (17%; mean age 66 ± 13 years). Secondary arterial embolic events occurred in 13 of 19 NBTE patients (68.4%), most frequently presenting as a stroke (63,1%). In non-NBTE patients, arterial embolic events occurred in 35 of 93 patients (37,3%, p=0,02). Discussion In this cohort of cancer patients, NBTE was associated with a significantly higher burden of arterial embolic events compared with non-NBTE endocarditis. This excess embolic risk is likely driven by the friability of NBTE vegetations and the absence of stabilizing inflammatory adhesions. These findings underscore the importance of early recognition and tailored management of NBTE to mitigate embolic risk