Supplementary Material for: Age-Specific Impact of Procedural Time on Outcomes After Endovascular Therapy for Large Vessel Occlusion: Insights from the K-NET Registry

Introduction
Although endovascular treatment (EVT) for large vessel occlusion (LVO) generally yields better outcomes in younger patients compared to older individuals, the efficacy of this intervention and the age-related variations in factors influencing outcomes remain insufficiently elucidated. This study aims to compare the outcomes of EVT between younger and older patients and to investigate the factors associated with favorable outcomes, with a particular focus on the relationship between procedural time and clinical results.
Method
The K-NET Registry comprised 3,187 EVT cases. For this analysis, 2,381 patients were included based on the following criteria: (1) a pre-stroke modified Rankin Scale score of 0–2, and (2) occlusion of the internal carotid artery or middle cerebral artery (M1 or M2). Patients were stratified into three age groups: <60 years (251 patients), 60–79 years (1,186 patients), and ≥80 years (944 patients). This stratification allowed for the evaluation of baseline characteristics, treatment outcomes, and factors associated with favorable outcomes. Procedural time was defined as the interval from puncture to successful recanalization.
Results
The proportion of women was higher in the <60 years group compared to the other age groups, while the prevalence of hypertension and dyslipidemia was significantly lower. Regarding stroke subtypes, intracranial artery stenosis/occlusion and arterial dissection were significantly more frequent in the <60 years group compared to the 60–79 and ≥80 years groups. The initial NIHSS scores were significantly lower in the <60 years group. The median procedural time was 54 minutes, 44 minutes, and 49 minutes for the <60, 60–79, and ≥80 years groups, respectively, with the <60 years group demonstrating the longest duration. However, recanalization rates did not differ significantly among the three groups. The proportion of patients achieving favorable outcomes was significantly different among the age groups: 68.5%, 54.3%, and 30.8%, respectively. Independent factors associated with favorable outcomes across all groups included lower initial NIHSS scores, ASPECTS ≥6, and successful recanalization. While procedural time was not a significant factor for the <60 years group, it was a significant predictor in the 60–79 and ≥80 years groups.
Conclusion
In EVT for LVO, NIHSS score, ASPECTS, and successful recanalization were independent predictors of favorable outcomes, irrespective of age. Although procedural time does not directly represent the full therapeutic time window, our findings indicate that prolonged puncture-to-recanalization time was significantly associated with worse outcomes in patients aged ≥60 years. These findings suggest that minimizing procedural time is especially critical in older populations, whereas younger patients may have greater tolerance for procedural delays due to more resilient cerebrovascular physiology.