Abstract Background Nonbacterial thrombotic endocarditis (NBTE) is a non-infectious condition characterized by thrombotic or inflammatory deposits on cardiac valves. Purpose This study aimed to elucidate the clinical and echocardiographic characteristics of patients diagnosed with NBTE and identify stroke-related factors and subsequent prognosis. Methods A total of 105 patients (mean age 59 ± 13 years, 50 men) diagnosed with NBTE between January 2005 and June 2023 at a single tertiary center were included in the study. NBTE diagnosis was confirmed by excluding patients with positive blood cultures and those meeting the Duke Criteria for possible or definite bacterial endocarditis. The cohort was categorized into 85 patients (81.0%) who experienced embolic events and 20 (19.0%) who did not. Further analysis was conducted among three groups: 41 patients (39.0%) with disabling stroke, 44 patients (41.9%) with non-disabling stroke, and 20 patients (19.0%) without embolic events to identify potential prognostic factors. Results Among the 105 patients with NBTE, active cancer was present in 98 patients (93.3%), while the remaining cases were attributed to non-cancerous causes. The most common underlying cancers were lung (32 patients, 32.7%), hepatobiliary (32 patients, 32.7%), genitourinary (19 patients, 19.4%), and gastrointestinal cancers (9 patients, 9.2%). NBTE predominantly affected the mitral valve (51 patients, 48.6%) and the aortic valve (36 patients, 34.3%), with multi-valvular involvement observed in 22 patients (21.0%). Moderate to severe valvular dysfunction was noted in 67 patients (63.8%). Vegetation size exceeding 5 mm was found in 91 patients (86.7%), and mobile vegetations were identified in 74 patients (70.5%). Factors significantly associated with embolic events included vegetation size larger than 5 mm [odds ratio (OR) 3.80, 95% confidence interval (CI) 0.89–16.11, p=0.007] and the presence of NBTE on the mitral valve [OR 3.18, 95% CI 1.03–9.79, p=0.044]. For disabling stroke, the presence of mobile vegetations [OR 4.07, 95% CI 1.22–13.55, p=0.022] and NBTE affecting the mitral valve [OR 5.12, 95% CI 1.39–18.83, p=0.014] were significant predictors (Figure 1). Conclusions Most patients with NBTE had underlying malignancies, with lung and hepatobiliary cancers being the most common. Larger vegetation and mitral valve involvement were associated with a higher risk of embolic events. Specifically, mobile vegetation and mitral valve involvement were strongly linked to an increased risk of disabling stroke.Factors associated with disable stroke