The Efficacy and Safety of Mechanical Thrombectomy in Posterior Circulation Large Vessel Occlusion as Compared to Anterior Circulation Large Vessel Occlusion: A Systematic Review.

Mechanical thrombectomy (MT) has been established as a standard of care for patients with stroke due to anterior circulation large vessel occlusion (AC-LVO). Due to a lack of robust evidence for the effectiveness of mechanical thrombectomy, intravenous thrombolysis (IVT) is still the only approved first-line acute reperfusion strategy for posterior circulation large vessel occlusion (PC-LVO). This systematic review analyzes and reports on the effectiveness and safety of MT in PC-LVO. A literature review was performed to identify all studies of patients with acute ischemic stroke due to PC-LVO who underwent MT with second-generation devices (stent retrievers and/or aspiration devices) that were reported between January 2017 and January 2023. The primary outcome was functional independence at 90 days, defined as a modified Rankin (mRS) score of ≤2. Secondary outcomes were successful recanalization (modified treatment in cerebral infarction score (mTICI) 2b/3), symptomatic intracerebral hemorrhage (sICH), and mortality at 90 days post-procedure. We looked at 13 studies with a total of 30,407 participants in four meta-analyses and 5951 participants in nine observational studies. In most studies, patients in the PC-LVO group were male and younger than the AC-LVO group. Higher baseline National Institutes of Health Stroke Scale (NIHSS) score, lower rates of IVT, longer onset-to-groin puncture time, lower likelihood of sICH, higher 90-day mortality rates, and higher futile recanalization rates were frequently observed in the PC-LVO group with a large discrepancy in the likelihood of functional independence at 90 days with majority studies showing comparable rates. Hence, in patients with acute ischemic stroke caused by the PC-LVO, successful reperfusion can be achieved via MT, though at the cost of higher mortality rates. Such futile recanalization can be avoided with the refinement of procedures through technical improvements, skills training, and recognition of reliable predictors associated with it, which might help increase the efficacy of MT in PC-LVO. Additionally, future large-scale RCTs comparing patient selection and interventional strategies to avoid futile interventions are also needed.