Age-stratified analysis of mechanical thrombectomy in octogenarians and nonagenarians: An institutional experience with focus on medical complications as independent predictors of functional outcomes

Objective: To identify clinically relevant age cutoffs and prognostic factors influencing functional outcomes in patients over 80 years undergoing mechanical thrombectomy (MT) for acute ischemic stroke (AIS). Methods: We analyzed 108 patients aged ≥81 years treated with endovascular therapy between January 2015 and September 2020. Recursive partitioning analysis identified the optimal age cutoff at 85.5 years, stratifying patients into younger (age<85.5, n=68) and older (age≥86, n=40) groups. Baseline characteristics, procedural metrics, and clinical outcomes were compared. Univariate and multivariate logistic regression analyses identified independent predictors of a favorable outcome (modified Rankin Scale ≤2 at 90 days). Results: Overall the favorable outcome was 38.9%, with significant differences between age groups (48.5% vs. 22.5%, P=0.007). Successful recanalization rates were similar (88.2% vs. 92.5%, P=0.479). Age≥86 years, higher initial National Institutes of Health Stroke Scale, longer procedure time, and medical complications, including pulmonary complications and acute kidney injury, were significant in univariate analysis. Multivariate analysis identified age≥86 years (OR 3.463, 95% CI 1.033-11.611, P=0.044), initial NIHSS (OR 1.146, 95% CI 1.048-1.252, P=0.003), procedure time (OR 1.033, 95% CI 1.013-1.054, P=0.001), pulmonary complications (OR 3.459, 95% CI 1.040-11.505, P=0.043), and acute kidney injury (OR 7.690, 95% CI 1.073-55.097, P=0.042) as independent predictors of unfavorable outcome. Conclusions: Age significantly affects functional outcomes in patients over 80 years old receiving MT. While procedural recanalization success remains high, medical complications, particularly pulmonary and renal complications, emerge as critical independent predictors of poor prognosis in this elderly population. Enhanced perioperative management of medical comorbidities may improve outcomes.