Elsevier

The Lancet Neurology

Volume 17, Issue 1, January 2018, Pages 47-53
The Lancet Neurology

Articles
Effect of general anaesthesia on functional outcome in patients with anterior circulation ischaemic stroke having endovascular thrombectomy versus standard care: a meta-analysis of individual patient data

https://doi.org/10.1016/S1474-4422(17)30407-6Get rights and content

Summary

Background

General anaesthesia (GA) during endovascular thrombectomy has been associated with worse patient outcomes in observational studies compared with patients treated without GA. We assessed functional outcome in ischaemic stroke patients with large vessel anterior circulation occlusion undergoing endovascular thrombectomy under GA, versus thrombectomy not under GA (with or without sedation) versus standard care (ie, no thrombectomy), stratified by the use of GA versus standard care.

Methods

For this meta-analysis, patient-level data were pooled from all patients included in randomised trials in PuMed published between Jan 1, 2010, and May 31, 2017, that compared endovascular thrombectomy predominantly done with stent retrievers with standard care in anterior circulation ischaemic stroke patients (HERMES Collaboration). The primary outcome was functional outcome assessed by ordinal analysis of the modified Rankin scale (mRS) at 90 days in the GA and non-GA subgroups of patients treated with endovascular therapy versus those patients treated with standard care, adjusted for baseline prognostic variables. To account for between-trial variance we used mixed-effects modelling with a random effect for trials incorporated in all models. Bias was assessed using the Cochrane method. The meta-analysis was prospectively designed, but not registered.

Findings

Seven trials were identified by our search; of 1764 patients included in these trials, 871 were allocated to endovascular thrombectomy and 893 were assigned standard care. After exclusion of 74 patients (72 did not undergo the procedure and two had missing data on anaesthetic strategy), 236 (30%) of 797 patients who had endovascular procedures were treated under GA. At baseline, patients receiving GA were younger and had a shorter delay between stroke onset and randomisation but they had similar pre-treatment clinical severity compared with patients who did not have GA. Endovascular thrombectomy improved functional outcome at 3 months both in patients who had GA (adjusted common odds ratio (cOR) 1·52, 95% CI 1·09–2·11, p=0·014) and in those who did not have GA (adjusted cOR 2·33, 95% CI 1·75–3·10, p<0·0001) versus standard care. However, outcomes were significantly better for patients who did not receive GA versus those who received GA (covariate-adjusted cOR 1·53, 95% CI 1·14–2·04, p=0·0044). The risk of bias and variability between studies was assessed to be low.

Interpretation

Worse outcomes after endovascular thrombectomy were associated with GA, after adjustment for baseline prognostic variables. These data support avoidance of GA whenever possible. The procedure did, however, remain effective versus standard care in patients treated under GA, indicating that treatment should not be withheld in those who require anaesthesia for medical reasons.

Funding

Medtronic.

Introduction

Multiple observational studies have suggested that, in general, patients treated with endovascular thrombectomy under general anaesthesia (GA) have poorer outcomes than those treated without GA.1 However, patients with more severe stroke or comorbidities might be more likely to be treated under GA, leading to the potential for confounding by indication. In MR CLEAN, sites specified their anaesthetic strategy prospectively and analysis of that trial found that the beneficial treatment effect of thrombectomy became non-significant in patients treated under GA.2 These results could lead to a reluctance to convert from an awake procedure to GA in cases where patient agitation or challenging vascular anatomy are preventing optimal revascularisation. By contrast, three small single-centre randomised trials that compared GA, which was done in accordance with strict protocols to maintain blood pressure, with conscious sedation, which made use of the same anaesthetic drugs at lower doses without intubation, did not detect a signal of harm, and functional independence was either no different or slightly increased in the patients who had GA.3, 4, 5 We analysed the pooled individual patient data from all randomised trials of stent retriever thrombectomy versus standard care. Our aim was to assess the influence of anaesthetic strategy on the treatment benefit of endovascular thrombectomy in broader contemporary practice.

Research in context

Evidence before this study

We searched PubMed for studies in any language examining the association of general anaesthesia (GA) with outcome in stroke patients undergoing endovascular thrombectomy between Jan 1, 2010, and May 31, 2017, using one of the terms “general anesthesia” OR “anesthetic” OR “sedation” with “thrombectomy”. Multiple observational studies showed a worse outcome in patients treated under GA compared with patients who were not treated under GA. Individual randomised trials of thrombectomy versus standard care found conflicting results on the effect of GA, varying between abolition of the thrombectomy treatment effect in MR CLEAN and no effect in THRACE. Three single-centre randomised trials of GA versus conscious sedation found either no difference in functional outcome between groups or a slight benefit of GA.

Added value of this study

To our knowledge, these data from contemporary, high-quality randomised trials form the largest study to date of the association between GA and the benefit of endovascular thrombectomy versus standard care. We found that GA for endovascular thrombectomy, as practised in contemporary clinical care across a wide range of expert centres during the randomised trials, was associated with a worse outcome than that seen when avoiding GA, independent of patient comorbidities. Patients still benefited from thrombectomy compared with standard care when treated under GA.

Implications of all the available evidence

The requirement for GA when the airway is compromised or the patient is agitated, which threatens the quality of revascularisation, should not deter clinicians from pursuing endovascular thrombectomy. The contrast between this analysis and the recent randomised trials comparing GA with conscious sedation suggests that, when GA is medically necessary, close attention should be paid to minimising anaesthetic delays to commence the procedure and maintaining physiological parameters such as blood pressure. A multicentre randomised trial to definitively address these issues is warranted.

Section snippets

Search strategy and selection criteria

For this systematic review and meta-analysis, we searched PubMed for randomised trials published in any language between Jan 1, 2010, and May 31, 2017, comparing endovascular thrombectomy that was predominantly performed with stent-retrievers versus standard care in patients with anterior circulation ischaemic stroke. The PubMed search string was ((“randomized controlled trial” [Publication Type]) AND ((thrombectomy[Title/Abstract]) OR (clot retrieval[Title/Abstract]) OR

Results

Seven randomised trials were identified from 65 studies returned by our search. All 1764 patients in these seven trials were included in our analysis, of whom 871 participants were randomly assigned to endovascular thrombectomy and 893 participants to standard medical care. After exclusion of 74 patients from the thrombectomy group (72 who did not undergo the procedure and two who had missing data on anaesthetic strategy), 236 (30%) of 797 endovascular patients were treated under GA (figure 1).

Discussion

Patients treated under GA had poorer outcomes compared with those treated without GA, after adjustment for baseline characteristics. The magnitude of this effect was clinically significant—for every 100 patients treated under GA versus those who were treated without GA, 18 patients would have worse functional outcome, including ten who would not achieve functional independence However, a significant benefit of endovascular thrombectomy over standard care was retained in patients treated under

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