Two recent systematic reviews [1, 2] have assessed the effectiveness of mechanical endovascular therapy (MET) to manage the acute phase of stroke, but new data have been published thereafter. In this context, our aim was to update these meta-analytic results and to investigate how effectiveness has changed over years. Our study was restricted to observational (single-arm) studies which were thought to better represent a real-world setting.

We searched all such studies evaluating MET and employing the end-point of any revascularization, complete revascularization, functional outcome, and mortality. As compared with the previous reviews [1, 2], 20 more studies were found, but unlike Baker et al. [2], case reports of ≤10 patients were excluded. Overall, we identified 58 studies published from 1994 to 2012 that evaluated 3066 patients (Appendix S1).

Our analysis of these 58 studies (proportion meta-analysis based on random-effect model [3, 4]) yielded the following pooled proportions with 95% confidence interval (95% CI): any revascularization, 80·7% (95% CI: 75·5% to 85·3%); complete revascularization, 50·6 (95% CI: 37·8 to 63·3); functional outcome, 39·2 (95% CI: 32·8 to 45·8); mortality, 24·5% (95% CI: 19·5% to 29·8%). Our results (see Appendix S1 for study-specific rates of individual end-points) are in keeping with those previously published [2, 3].

Figure 1 shows the results of our meta-regression (based on standard regression techniques [5]) that separately examined the four end-points. In these analyses, MET was associated with an improvement in total revascularization rate and a decrease in mortality over time. While the time dependency of these indexes is likely to reflect improvements in devices, techniques, and expertise, the shortcomings of our analysis must however be kept in mind (e.g. the single-arm nature, and lack of randomization and blinding in these studies).


Figure 1. Meta-regression analysis of temporal trends for four end-points measured in patients with acute ischaemic stroke treated with MET. End-points: any recanalization (Panel a, 48 studies), complete recanalization (Panel b, 38 studies), functional outcome (Panel c, 41 studies), and mortality (Panel d, 46 studies); y-axis, percent rate; x-axis, calendar year. The regression equations were: RATE = 0·422 × YEAR − 760·06 (P = 0·635) in Panel a, RATE = 9·142 × YEAR − 18 313·4 (P < 0·0001) in Panel b, RATE = 0·458 × YEAR − 883·22 (P = 0·608) in Panel c, RATE = −1·669 × YEAR + 3373·66 (P = 0·016) in Panel d. Symbols: each study is represented by a circle the diameter of which is proportional to its statistical weight.

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In conclusion, our results suggest that, in a real-world setting, MET shows a progressively better effectiveness with time, but the heterogeneity of its outcomes is still wide.


  1. Top of page
  2. References
  3. Supporting Information
  • 1
    Baker WL, Colby JA, Tongbram V et al. Neurothrombectomy devices for the treatment of acute ischemic stroke: state of the evidence. Ann Intern Med 2011; 154:243252.
  • 2
    Rouchaud A, Mazighi M, Labreuche J et al. Outcomes of mechanical endovascular therapy for acute ischemic stroke: a clinical registry study and systematic review. Stroke 2011; 42:12891294.
  • 3
    Vasques F, Messori A, Lucenteforte E, Biancari F. Immediate and late outcome of patients aged 80 years and older undergoing isolated aortic valve replacement: a systematic review and meta-analysis of 48 studies. Am Heart J 2012; 163:477485.
  • 4
    Messori A, Fadda V, Maratea D, Trippoli S. Meta-analysis of observational studies to evaluate immediate outcomes after endarterectomy or stenting for carotid artery stenosis. Ann Vasc Surg 2012; 26:166167.
  • 5
    Messori A, Del Santo F, Fadda V, Maratea D, Trippoli S. Interpreting randomised trials evaluating newer agents or interferon in multiple sclerosis. Eur J Clin Pharmacol 2012; 68:441442.

Supporting Information

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  2. References
  3. Supporting Information

Appendix S1. Fifty-eight studies reported in the meta-analyses by Baker et al. and by Rouchaud et al. evaluating MET and employing the end-point of any revascularization, complete revascularization, functional outcome, and mortality.

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