Safety and efficacy of mechanical thrombectomy in distal medium vessel occlusions: Experience and real-world data from an Italian stroke hub centre

Background and purpose: Distal-medium vessel occlusions (DMVOs) contribute to approximately 25-40 % of cases of ischemic stroke. Intravenous thrombolysis (IVT) achieved a complete recanalization in <50 % of cases. Observational studies have demonstrated comparable efficacy and safety of mechanical thrombectomy (MT) in DMVOs compared to LVOs. Recently published RCTs have shown that MT plus best medical therapy in DMVOs does not improve the outcome compared to best medical therapy alone METHODS: We conducted a retrospective observational study involving patients with acute ischemic stroke (AIS) and primary or secondary DMVO according to literature classification. DMVOs were defined as occlusion in the A2, A3, distal M2 or its single branch, M3, P2, P3, PICA, SCA and AICA. The primary endpoint was to evaluate the safety and efficacy of MT alone in DMVOs compared to IVT. Efficacy was assessed by considering the change in NIHSS from admission to discharge, 3 months Modified Rankin Scale (mRS), 3 months mortality rate and recanalization rate. Safety was assessed based on haemorrhagic transformation and procedural complications. As a secondary endpoint we compared primary and secondary DMVO to highlight any differences.

Results: In primary plus secondary DMVO after propensity score analysis there were no statistically significant differences in efficacy and safety between MT and IVT though a positive trend for NIHSS reduction in the MT group. Sub-analysis of primary DMVO did not show significant differences between the two groups. MT group achieved an excellent recanalization rate with mTICI ≥2b in 95 % of cases and no procedural complications occurred.

Conclusions: MT in DMVOs showed an excellent recanalization rate and few procedural complications. New RCTs are needed to compare the efficacy and safety of MT alone versus IVT alone in primary and secondary DMVOs separately.