Assessment of collateral circulation in patients with anterior circulation stroke treated with mechanical thrombectomy as a predictor of long-term clinical outcomes

Background: Mechanical thrombectomy (MT) is the most effective treatment for large vessel occlusion (LVO) stroke. Despite this treatment, clinical outcomes are highly variable. Purpose: To evaluate the role of collateral circulation in patients undergoing MT as a determinant of clinical outcome, especially in the long term. Material and Methods: The study included 80 patients who underwent MT for LVO of the anterior cerebral circulation. Patient data were collected on demographics, baseline neurological status, imaging studies (including ASPECTS and collateral circulation score), and clinical status of the patients as determined by NIHSS at discharge and by modified Rankin Scale (mRS) score at 3 and 12 months postoperatively. Results: Patients with good collateral circulation were compared to the group with poor collateral circulation: they had significantly lower NIHSS at 24 h (median NIHSS 8 vs. 16; P < 0.001) and at the time of discharge (median NIHSS 3.5 vs. 13; P < 0.001). At 3 months, patients with good collateral circulation had a significantly higher chance of achieving a good functional outcome (mRS = 0-2) (62.75% vs. 10.34%; P < 0.001) and had a lower mortality (13.73% vs. 41.38%; P = 0.005). The benefits of good collateral circulation extended into the long term. At 12 months, patients with good collateral circulation were significantly more likely to have good functional outcome (mRS = 0-2) (60.78% vs. 10.34%; P < 0.001) and lower mortality (19.61% vs. 44.83%; P = 0.017). Conclusion: Good collateral circulation increases the likelihood of favorable outcome in MT-treated stroke patients at discharge, 3 months, and 12 months.