Endovascular treatment versus intravenous thrombolysis alone in isolated M2 occlusion: a meta-analysis

Optimal reperfusion strategies for M2 occlusion are still uncertain, with previous studies questioning benefit of mechanical thrombectomy (MT) over intravenous thrombolysis alone (IVT). Here we systematically reviewed and meta-analyzed data from studies comparing IVT alone vs MT with/without previous IVT, to define risk/benefit profile of each paradigm.

The study followed PRISMA guidelines. PubMed, EMBASE, and Cochrane Central were searched only for RCTs comparing MT with or without IVT vs IVT alone in adults with acute ischemic stroke and M2 occlusion. Primary endpoint was functional independence at 90 days (modified Rankin Scale<3); secondary endpoints were represented by symptomatic intracranial hemorrhage (sICH) and good recanalization (TICI>2a). Odds ratios for endpoints were pooled with meta-analysis and compared between reperfusion strategies.

Seven studies (n=779) were included, all of high quality. Rate of good functional outcome was similar for MT and IVT (62.4% vs 66.3%; OR=0.73; 95%CI: 0.38-1.41; p_{heterogeneity}=0.008) (Fig. 1).sICH was significantly more frequent in the MT group (8.5%) vs IVT group (3%) (OR 2.76, 95%CI 1.19-6.36, p_{heterogeneity}=0.14). Good recanalization (TICI>2a) rate was higher in MT group vs IVT alone group (81.2% vs 51.4%; OR 3.99; 95%CI: 1.98-8.94; p_{heterogeneity}=0.80).

IVT alone provides similar clinical benefit compared to MT with/without IVT in cases of M2 occlusion. MT quadruplicates rates of good recanalization, but triplicates risk of sICH. Further trials are needed to define if MT confers any advantage over IVT for M2 occlusion.