BACKGROUND AND OBJECTIVES: Whether thrombectomy compared with best medical treatment (BMT) improves outcome in patients with stroke and carotid artery dissection (CAD) is unknown. METHODS: This was an international observational study based on prospective nationwide Austrian, German, and Swiss stroke registries. Patients with large vessel occlusion (LVO) due to CAD were compared according to treatment modality (thrombectomy vs BMT including intravenous thrombolysis) and to admission stroke severity NIH Stroke Scale (NIHSS) <
6 vs NIHSS ≥6. The primary outcome was the favorable functional outcome (modified Rankin Score 0-2) at 3 months. RESULTS: Of 1,023 patients (mean age 54 years, 72% males), 516 received thrombectomy and 507 received BMT. After robust adjustment, thrombectomy was associated with favorable outcome in patients presenting with NIHSS ≥6 (adjusted risk ratio (aRR) = 1.77, 95% CI 1.44-2.17). In those presenting with NIHSS <
6, thrombectomy was associated with unfavorable outcome (aRR 1.68, CI 1.1-2.56) as compared with BMT. DISCUSSION: Thrombectomy improved functional outcome in patients with LVO due to CAD and admission NIHSS ≥6, but not NIHSS <
6 points. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that for patients with LVO due to CAD and admission NIHSS ≥6 points, thrombectomy compared with BMT significantly increases the probability of favorable outcome.