Prevalence and Clinical Predictors of Stroke Mimics in the Extended Thrombectomy Window: A Cross-Sectional Study in Vietnam

Background: Stroke mimics pose diagnostic challenges in the emergency department, particularly in patients presenting within the 4.5-24 hour thrombectomy window. Misdiagnosis may result in unnecessary interventions or delayed stroke treatment. This study aimed to determine the prevalence, clinical characteristics, and predictors of stroke mimics among suspected stroke patients in this timeframe. Methods: We conducted a cross - sectional study at People Hospital 115, Vietnam (February-June 2024). Patients presenting with acute neurological deficits underwent standardized magnetic resonance imaging. Logistic regression identified independent predictors of SMs. Results: Among 1,180 patients (mean age 62.6 years; 58.6% male), 346 (29.3%) were diagnosed with SMs. Compared to stroke patients, SMs were more likely to be male (77.2% vs. 50.8%, P < 0.001), had lower NIHSS scores (median 8 vs. 12.5, P = 0.013), and shorter hospital stays (median 2 vs. 4 days, P < 0.001). Independent predictors included bilateral leg weakness (OR 23.9; 95% CI, 6.9-33.8), quadriparesis (OR 25.4; 95% CI, 7.8-35.1), dizziness (OR 14.6; 95% CI, 7.1-32.7), headache (OR 13.2; 95% CI, 6.5-26.8), seizures (OR 13.9; 95% CI, 6.7-28.5), altered consciousness (OR 4.9; 95% CI, 2.4-9.8), numbness (OR 6.4; 95% CI, 2.1-12.5), and male sex (OR 3.3; 95% CI, 2.5-4.4). Atrial fibrillation was a negative predictor (OR 0.33). Conclusions: Stroke mimics account for nearly one-third of suspected strokes within the extended thrombectomy window. Recognizing specific clinical predictors can improve diagnostic accuracy, reduce unnecessary interventions, and optimize ED resource allocation. Integration of these predictors into triage protocols could support faster, safer decision-making in clinical practice.