Whether mTICI 3 or mTICI 2b is better in patients with vertebrobasilar artery occlusion undergoing endovascular treatment depends on pc-ASPECTS

Background The clinical relevance of differentiating between mTICI (modified Thrombolysis In Cerebral Infarction) 2b and mTICI 3 in patients with vertebrobasilar artery occlusion (VBAO) remains unclear. This study aimed to investigate whether mTICI 3 improves functional outcomes compared with mTICI 2b in patients with VBAO and whether this improvement differs according to extent of ischemic damage. Methods This retrospective study enrolled patients with VBAO within 24 hours of the estimated occlusion time at 65 stroke centers in a nationwide registration in China. The primary outcome was favorable functional outcome (modified Rankin scale score 0–3) at 90 days. Patients were matched by final mTICI grade using propensity score matching (PSM) and inverse probability of treatment weighting (IPTW). Logistic regression and ordinal regression models were used to assess the impact of mTICI 2b versus mTICI 3 grading on prognosis, based on different extent of ischemia damage (posterior circulation Alberta Stroke Program Early CT Score—pc-ASPECTS of 9–10, 7–8, and 3–6) and treatment strategies (bridging therapy and direct endovascular therapy (EVT)). Results A total of 2075 patients with VBAO and successful reperfusion were included, 652 patients (31.4%) achieved mTICI 2b and 1423 patients (68.6%) achieved mTICI 3. After adjustment for confounders, achieving mTICI 3 following EVT in patients with VBAO and pc-ASPECTS 9–10 (OR 1.54, 95% CI 1.16 to 2.03) and pc-ASPECTS 7–8 (OR 1.80, 95% CI (1.26 to 2.56) were associated with favorable functional outcome compared with mTICI 2b, especially in those receiving direct EVT. However, in patients with pc-ASPECTS≤6, functional outcomes at 90 days did not differ between mTICI 3 and mTICI 2b (OR 1.12, 95% CI 0.67 to 1.88), irrespective of using bridging therapy or direct EVT. Conclusion In patients with VBAO undergoing EVT with pc-ASPECTS>6, achieving mTICI 3 favors better outcomes compared with mTICI 2b, especially in those receiving direct EVT. However, in patients with pc-ASPECTS≤6, mTICI 3 did not improve functional outcomes compared with mTICI 2b. Interventionalists should carefully assess the risk-benefit of additional maneuvers once mTICI 2b reperfusion is restored in EVT for patients with VBAO and pc-ASPECTS≤6. Further studies are needed to guide treatment decisions in these cases.