Randomised controlled trial needed to determine safety of direct mechanical thrombectomy as compared with intravenous thrombolysis prior to mechanical thrombectomy

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The meta-analysis trial showed no evidence that rates of successful reperfusion differed in direct mechanical thombectomy and intravenous thrombolysis prior to mechanical thrombectomy.

In contrast to previous synopses and when analysis is confined to studies with a low risk of selection bias (i.e., comparable IVT (intravenous thrombolysis) -eligible patients in both treatment strategy groups), data published in the Journal of NeuroInterventional Surgery suggest that for patients who finally undergo mechanical thrombectomy, direct mechanical thrombectomy may offer comparable safety and efficacy as compared with intravenous thrombolysis prior to mechanical thrombectomy.

The analysis showed that outcome comparisons yield mixed results when less comparable patients are considered (direct mechanical thrombectomy in IVT-ineligible patents vs. intravenous thrombolysis prior to mechanical thrombectomy in IVT-eligible patients). These findings are the rationale of randomised controlled trials, comparing both treatment approaches.

The authors, Kaesmacher et al, write: “Available data do provide substantial indications of clinical non-inferiority, suggesting that the conduct of randomised clinical trials evaluating direct mechanical thrombectomy versus intravenous thrombolysis prior to mechanical thrombectomy in large vessel occlusion (LVO) patients is appropriate when including only major vessel occlusions and when rapid access to endovascular treatment can be assured. The value of pre-interventional recanalisation in intravenous thrombolysis prior to mechanical thrombectomy needs further evaluation and should be reported more consistently.”

To look at whether there is a benefit the group performed a meta-analysis in accord with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The pooled effect sizes were calculated using the inverse variance heterogeneity model and displayed as summary odds ratio (sOR) and corresponding 95% confidence interval (95% CI). Sensitivity analysis was performed by distinguishing between studies including direct mechanical thrombectomy patients eligible for IVT (IVT-E) or ineligible for IVT (IVT-IN).

The primary outcome measures were functional independence (modified Rankin Scale ≤2) and mortality at day 90, successful reperfusion, and symptomatic intracerebral haemorrhage.

The analysis looked at 20 studies, incorporating 5,279 patients. They found that there was no evidence that rates of successful reperfusion differed in direct mechanical thrombectomy and intravenous thrombolysis prior to mechanical thrombectomy patients (sOR 0.93, 95% CI 0.68 to 1.28). In studies including IVT-IN direct mechanical thrombectomy patients, they found that patients undergoing direct mechanical thrombectomy tended to have lower rates of functional independence and had higher odds for a fatal outcome as compared with intravenous thrombolysis prior to mechanical thrombectomy patients (sOR 0.78, 95% CI 0.61 to 1.01 and sOR 1.45, 95% CI 1.22 to 1.73). Importantly however, they also highlight that “No such treatment group effect was found when analyses were confined to cohorts with a lower risk of selection bias (including IVT-E direct mechanical thrombectomy patients).”

The authors conclude: “The quality of evidence regarding the relative merits of intravenous thrombolysis prior to mechanical thrombectomy versus direct mechanical thrombectomy is low. When considering studies with lower selection bias, the data suggest that direct mechanical thrombectomy may offer comparable safety and efficacy as compared with intravenous thrombolysis prior to mechanical thrombectomy. The conduct of randomised-controlled clinical trials seems justified.”

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