Is more evidence needed for thrombectomy in basilar artery occlusion
strokearterythrombectomystatisticsIntroductionThe benefit of mechanical thrombectomy for stroke associated with anterior circulation large vessel occlusion (LVO) is well established and among the most effective treatments in medicine.1 Stroke associated with basilar artery occlusion (BAO) was not included in the seminal thrombectomy randomised clinical trials (RCTs). BAO accounts for 1% of the ischaemic strokes and 5% 10% of the LVO, but 70% 80% of BAO victims evolve to death or full dependence.2 3 The terminal nature of the brainstem and thalamic circulations may predispose to such dismal outcomes.Only two RCT designed to assess the efficacy of early (2 4 Given the prior evidence for thrombectomy benefit for anterior circulation stroke is well settled; BAO stroke shares a similar physiopathology with very poor prognosis; the two available BAO trials had limited sample sizes but large absolute differences on the functional outcomes; we propose that an aggregated analysis of the BEST and BASICS trials should be performed under a Bayesian approach.MethodsThrombectomy RCTs designed for the enrollment of BAO associated stroke patients were eligible for inclusion. The only exclusion criterion was the endovascular intervention time window: only early (6 8hours) thrombectomy was considered. The MEDLINE and EMBASE databases were searched for articles in any language inception to October 2020. The descriptors ((basilar) OR (vertebrobasilar)) AND (stroke) AND (thrombectomy) were used within the filter ‘RCT’.A Bayesian random effects meta analysis was modelled with a prior choice of effect parameter based on the results of the HERMES collaboration, in which thrombectomy was associated with a higher odd of modified Rankin Score (mRS) 0 3 at 90 days (OR 2.25, 95%CI 1.80 to 2.82).1 Thus, a Gaussian prior with mean 0.811 (2.25 in the logarithmic OR scale) and SD 0.414 (percentile 2.5 corresponding to the null effect, since a prior hypothesis of a thrombectomy deleterious effect was highly unlikely) was appropriate (online supplemental figure 1). Five studies were duplicates and another 35 were excluded because they were not an RCT or did not include basilar artery stroke. There are no other related ongoing RCT, except for the Basilar Artery Occlusion Chinese Endovascular Trial (online supplemental table 1).In the BEST trial intention to treat (ITT) analysis, there was no difference between treatment groups in the 90 day primary outcome, mRS 0 3 (intervention, 28/66, 42% and control, 21/65, 32%; OR 1.54, 95%CI 0.76 to 3.15). Similarly, no difference was found in the BASICS trial primary outcome ITT analysis (intervention, 68/154, 44% and control, 55/146, 38%; OR 1.31, 95%CI 0.82 to 2.08). In both trials, the secondary efficacy and safety outcomes were similar between groups.Mechanical thrombectomy was associated with favourable functional outcomes in BAO stroke, with an OR 1.62% and 95% credible interval (high density interval) 1.01 2.77 (figure 1A and online supplemental figure 2). The observed absolute risk reduction would translate to a number need to treat of 13. Using classical (‘frequentist’) estimates, meta analysis would result inconclusive, with an OR 1.37 (95% CI 0.93 to 2.02) (figure 1B).Meta analysis for 90 day favourable functional outcome (MRS 0 (A) Bayesian approach. (B) Traditional approach.Open in new tabFigure 1 Meta analysis for hermes belt buckle replica sale
90 day favourable functional outcome (MRS 0 3). (A) Bayesian approach. (B) Traditional approach.