Influence of Comorbidity on Endovascular Thrombectomy Outcomes for Medium-Vessel Occlusion Stroke: A Nationwide Prospective Observational Study

Background: Comorbidity burden may affect the outcome following endovascular thrombectomy (EVT) for medium-vessel occlusions. Since patients with high comorbidity burden are likely to be underrepresented in trials on EVT for medium-vessel occlusions, observational data are needed to assess the benefit of EVT for these patients. Methods: We conducted an observational study on all prestroke independent patients treated with EVT for medium-vessel occlusions in the MCA territory in Sweden from 2015 to 2021. Comorbidity burden was weighted according to the Charlson Comorbidity Index (CCI) and categorized into no comorbidity (CCI 0); moderate to severe comorbidity (CCI 1-2); and very severe comorbidity (CCI >= 3). The primary outcome was a favorable outcome (modified Rankin Scale 0-2) at 90 days after EVT in relation to comorbidity burden. Excellent outcome (modified Rankin Scale 0-1) and symptomatic intracranial hemorrhage were secondary outcomes. In an exploratory analysis, we compared outcomes on the basis of successful recanalization (modified Thrombolysis in Cerebral Infarction 2b-3). Results: Among 983 patients, 37% had no comorbidity (CCI 0), 35% had moderate to severe comorbidity burden (CCI 1-2), and 27% had a very severe comorbidity burden (CCI >= 3). Favorable and excellent outcomes were most frequent in the CCI 0 group (61% and 25%) and least frequent in the CCI >= 3 group (29% and 13%) (P < 0.001), but there was no significant difference in symptomatic intracranial hemorrhage rates. Successful recanalization reduced the severity of stroke symptoms (National Institutes of Health Stroke Scale) and was associated with increased rates of favorable outcomes for all CCI groups: CCI 0: odds ratio, 4.25 (95% CI, 2.18-8.25); CCI 1 to 2: odds ratio, 3.39 (95% CI, 1.71-6.72); and CCI >= 3: odds ratio, 2.57 (95% CI, 1.14-6.00). Conclusion: Moderate to very severe comorbidity burden is common among EVT-treated patients with medium-vessel occlusions in routine clinical practice and is associated with worse prognosis compared with patients with no comorbidity. Our results highlight the importance of achieving successful recanalization, which appears highly beneficial across all comorbidity levels.