Background and Purpose Distal intracranial vessels have a longer access route, smaller caliber, and thinner wall compared to proximal intracranial arteries. Therefore, distal large vessel occlusions (LVOs) were not an initial target for mechanical thrombectomy (MT) and were excluded from all MT trials. As a result, the benefit of MT and efficacy of different MT techniques remain unclear for distal LVOs. In this systematic review, we aimed to compare the performance of different thrombectomy techniques in distal LVOs.

Methods PubMed database was searched for studies examining the utility of MT in distal LVOs (MCA M2–3-4, ACA, and PCA). Studies providing data for aspiration thrombectomy (ASP), stent retriever thrombectomy (SR), and combined ASP + SR technique were included. Noncomparative studies were excluded. The following outcomes were assessed: Successful recanalization (TICI ≥ 2b), functional independence (mRS: 0–2), and symptomatic intracranial hemorrhage (sICH). Nested Knowledge AutoLit platform was utilized for literature search, screening, and data extraction. Pooled data were presented as descriptive statistics for each thrombectomy technique.

Results Seven studies comprising 1051 MT procedures were identified. Separate data for first-line thrombectomy method were available in 869 cases (ASP: 195; SR: 325; SR + ASP: 349). The overall successful recanalization rate was 81% (854/1051) for distal LVOs. SR (85%, 276/325) and ASP + SR (84%. 292/349) had higher successful recanalization rates compared to ASP alone (71%, 140/195). The overall functional independence rate was 55% (502/903) among distal LVOs. The ASP alone group had the lowest functional independence rate (50%, 98/194), and functional independence rates of SR and SR + ASP groups were 57% (174/304) and 62% (174/282), respectively. Finally, rates of sICH prevalence were 14% (14/99) for ASP group, 5% (9/175) for SR group, and 1% (1/80) for SR + ASP group.

Conclusions Our systematic review supports that MT is a safe and effective treatment option for distal LVOs. Additionally, in our study, SR and SR + ASP groups had better safety and efficacy outcomes compared to ASP alone. However, further research is needed to better compare the performance of first-line MT strategies in distal LVOs.

Disclosures C. Bilgin: None. K. Hutchison: None. N. Hardy: None. J. Pederson: None. K. Kallmes: None. D. Kallmes: None. W. Brinjikji: None.