Abstract Number: Esoc2026a2305 Impact of Vascular Tortuosity on Mechanical Thrombectomy Outcomes: A Systematic Review Highlighting Heterogeneity in Definitions, Occlusion Sites, and Hemorrhagic Complications

Abstract Background and aims Vascular tortuosity impacts mechanical thrombectomy (MT) outcomes, yet substantial heterogeneity in definitions, measurement methods, and outcome reporting limits clinical application. We systematically reviewed tortuosity's impact on MT, stratifying by methodological heterogeneity, occlusion site, and safety outcomes. Methods We analyzed pooled 3,103 patients from clinical studies and examined heterogeneity across tortuosity definitions, vascular segments, occlusion locations, and procedural techniques. Results Methodological heterogeneity was profound; 16 distinct tortuosity index methods exist across 4 mathematical categories (morphological, distance-based, trigonometrical, curvature-based), and all 9 carotid tortuosity studies employed different definitions. For LVO, carotid tortuosity prolonged procedure times (7/9 studies, 78%) and reduced recanalization (5/9 studies, 56%), accounting for ~30% of procedural time variation. For MDVO, intracranial tortuosity significantly affected efficacy (ICA-TI: aOR 0.51 for first-pass effect; MCA-TI: aOR 0.77 for complete recanalization) and hemorrhagic complications. M1 tortuosity in M2 occlusions dramatically increased any ICH (64% vs. 35%; aOR 3.09, p=0.004) and SAH (49% vs. 27%; aOR 2.61, p=0.01). Critically, MCA bending length predicted SAH (aOR 2.47) while vessel diameter at occlusion predicted sICH (aOR 4.04). Despite these procedural and safety associations, no study (0/9 in pooled analysis) demonstrated significant impact on 90-day functional independence. Conclusions Vascular tortuosity significantly impacts MT procedural efficiency and hemorrhagic complications, with site-specific effects: extracranial tortuosity affects access/recanalization while intracranial tortuosity uniquely increases hemorrhagic risk in distal occlusions. The dissociation between procedural metrics and functional outcomes, the "tortuosity paradox", equires further investigation. Urgent standardization of tortuosity measurement is needed to establish clinically actionable thresholds for patient selection and technique optimization. Conflict of interest Mohamed F Doheim: Nothing to disclose. Raul G. Nogueira: PI of DUSK trial for MeVOs.