Efficacy and safety of mechanical thrombectomy alone for the treatment of acute ischemic stroke

Background: Intravenous thrombolysis (IVT) and bridging therapy (BT) (IVT+mechanical thrombectomy [MT]) are the main treatments for acute ischemic stroke (AIS). Recent studies suggested that the curative effects of MT alone and BT are equivalent. However, there is no consensus regarding the curative effect and safety of MT alone. Therefore, a systematic review and meta-analysis are needed for further clarification. Methods: Seven databases, including PubMed, EMBASE, and Web of Science, were searched up to May 2021 for studies on MT alone and BT for the treatment of AIS. The modified Rankin scale (mRS) score and recanalization rate were the efficacy outcomes. Symptomatic and asymptomatic intracranial hemorrhage (SICH and aSICH) and mortality were the safety outcomes. RevMan 5.4 was used for analysis. Results: Thirty-five studies including 10,462 patients (MT alone: 4,612, BT: 5850) were selected. The improvement in the mRS score (mRS1: risk ratio [RR]=1.22, 95% confidence interval [CI] 1.09-1.35; P<.05; mRS2: RR=1.21, 95% CI 1.12-1.31; P<.05) was greater and the recanalization rate (RR=1.06, 95% CI 1.02-1.09; P<.05) was higher with BT than with MT alone. The rates of overall intracranial hemorrhage (RR=1.20, 95% CI 1.07-1.34; P <.05) and aSICH (RR=1.31, 95% CI 1.41-1.51; P .05) were lower after MT alone than after BT. There was no significant difference in the rate of SICH (RR=1.05, 95% CI.87-1.26; P .05). The mortality rate (RR=.76, 95% CI.70-.83; P<.05) was higher after MT alone than after BT. Conclusions: MT alone is inferior to BT regarding improvements in neurological function and recanalization and is associated with a higher mortality rate, although the associated rate of aSICH is lower.