First pass effect vs multiple passes complete reperfusion: A retrospective study

Background and purpose: First pass effect (FPE) is defined as achieving modified treatment in cerebral infarction (mTICI) grade 2c/3 reperfusion from the first pass and is associated with more favorable outcomes. We aimed to compare FPE and non-FPE using a large database and further compare first-pass mTICI 2b with multiple passes mTICI 3. Methods: A retrospective cohort study of acute ischemic stroke patients who received mechanical thrombectomy at a high-volume center was performed. Baseline characteristics and outcomes including rates of discharge and 90-day functional independence (modified Rankin Scale ≤2), mortality, symptomatic, and asymptomatic intracerebral hemorrhage were compared. Results: Of the 637 patients included, 294 achieved FPE; 161 patients had multiple passes mTICI 3 and 36 had first pass mTICI 2b. Propensity-score matching resulted in 211 matched pairs for FPE vs non-FPE, and 30 matched pairs for multiple passes mTICI 3 vs first pass mTICI 2b. The FPE group had significantly more instances of discharge (33.6% vs 19.4%, p = 0.001) and 90-day functional independence (51.7% vs 40.8%, p = 0.032), and lower rates of mortality (18.0% vs 27.5%, p = 0.027) compared to non-FPE. There was no significant difference between first pass mTICI 2b and multiple passes mTICI 3 concerning any studied outcomes. Conclusions: First pass mTICI 2c/3 is safer and is associated with higher rates of functional independence. We did not observe a significant difference between first pass mTICI 2b and multiple passes mTICI 3. The limitations of this study prevent us from drawing conclusions related to the difference between them and calls for future large-scale studies to explore that further.