Bridging versus Direct Mechanical Thrombectomy in Acute Ischemic Stroke: A Subgroup Pooled Meta-Analysis for Time of Intervention, Eligibility, and Study Design

Abstract

Background and Aim: The risk/benefit profile of intravenous thrombolysis (IVT) prior to endovascular thrombectomy (EVT) in acute ischemic stroke is still unclear. We provide a systematic review and meta-analysis including studies comparing direct EVT (dEVT) vs. bridging treatment (IVT + EVT), defining the impact of treatment timing and eligibility to IVT on functional status and mortality. Methods: Protocol was registered with PROSPERO (CRD42019135915) and followed PRISMA guidelines. PubMed, EMBASE, and Cochrane Central were searched for randomized controlled trials (RCTs), retrospective, and prospective studies comparing IVT + EVT vs. dEVT in adults (≥18) with acute ischemic stroke. Primary endpoint was functional independence at 90 days (modified Rankin Scale <3); secondary endpoints were (i) good recanalization (thrombolysis in cerebral infarction >2a), (ii) mortality, and (iii) symptomatic intracranial hemorrhage (sICH). Subgroup analysis was performed according to study type, eligibility to IVT, and onset-to-groin timing (OGT), stratifying studies for similar OGT. ORs for endpoints were pooled with meta-analysis and compared between reperfusion strategies. Results: Overall, 35 studies were included (n = 9,117). No significant differences emerged comparing patients undergoing dEVT and bridging treatment for gender, hypertension, diabetes, National Institute of Health Stroke Scale score at admission. Regarding primary endpoint, IVT + EVT was superior to dEVT (OR 1.44, 95% CI 1.22–1.69, p < 0.001, p_{heterogeneity}<0.001), with number needed to treat being 18 in favor of IVT + EVT. Results were confirmed in studies with similar OGT (OR 1.66; 95% CI 1.21–2.28), shorter OGT for IVT + EVT (OR 1.53, 95% CI 1.27–1.85), and independently from IVT eligibility (OR 1.53, 95% CI 1.29–1.82). Mortality at 90 days was higher in dEVT (OR 1.38; 95% CI 1.09–1.75), but no significant difference was noted for sICH. However, considering data from RCT only, reperfusion strategies had similar primary (OR 0.91, 95% CI 0.6–1.39) and secondary endpoints. Differences in age and clinical severity across groups were unrelated to the primary endpoint. Conclusions: Compared to dEVT, IVT + EVT associates with better functional outcome and lower mortality. Post hoc data from RCTs point to substantial equivalence of reperfusion strategies. Therefore, an adequately powered RCTs comparing dEVT versus IVT + EVT are warranted.