Clinical outcomes of first-pass effect after mechanical thrombectomy for acute ischemic stroke: A systematic review and meta-analysis

The first-pass effect (FPE) during a mechanical thrombectomy for ischemic stroke results in favorable clinical outcomes and low symptomatic intracranial hemorrhage (sICH) rates according to individual observational studies. We performed an integrated study-level meta-analysis to compare the clinical outcomes and safety profiles of single (FPE group) and multiple passages (non-FPE group) of devices in patients who achieved successful recanalizations.A literature search of the PubMed, Embase, and Cochrane databases for FPE was conducted. We included studies comparing outcomes between patients with and without FPE for 90-day favorable outcome, mortality, and sICH. The results from the pooled analysis using the random-effects model were presented as odds ratios (OR) and 95% confidence intervals (CI).Of the 8 selected studies comprising 2308 patients, the overall rates of the FPE were 40.3% (930/2308). The FPE was significantly associated with more 90-day favorable outcomes (OR: 1.31, 95% CI: 1.13-1.51) and lower mortality (OR: 0.53, 95% CI: 0.34-0.81), but there were no significant differences in sICH rates (OR: 0.80, 95% CI: 0.50-1.30). The results of the meta-regression analysis showed that there was no confounding effect of intravenous thrombolysis prior to thrombectomy.Our findings indicated that patients who achieved the FPE would have more 90-day favorable outcomes and lower mortality compared with non-FPE patients. However, there was a limited association between the FPE and reduced sICH rates.