Michael Söderman, Department of Neuroradiology, Karolinska University Hospital, Stockholm, Sweden told delegates at the European Society of Minimally Invasive Neurological Therapy (ESMINT; 5–8 September, Nice, France) congress that there are studies that indicate the benefit of mechanical thrombectomy if it is performed with a collaborative team of interventional neuroradiologists, neurologists and neurosurgeons and in dedicated stroke centres.
In his presentation he said that the meta-analysis by Mullen et al of 52 studies (>10 patients; 5019 subjects) “found no evidence that one treatment strategy was superior with respect to safety and efficacy, supporting clinical equipoise between reperfusion strategies”. However, this meta-analysis compared many different reperfusion strategies and was limited to the period 1999-2008, ie. before the stentreivers appeared on the market.
He then went on to look at stentriever studies (TREVO-2, Penumbra 3D and REVIVE) which largely saw high recanalisation rates (68%, 85% and 100%, respectively) and low complication rates (8%, 0% and 0%, respectively).
The current largest study (STAR) on mechanical thrombectomy with the Solitaire device included 202 patients and outcomes were similar to other studies. The recanalization rate was 80% and 58% had a favourable outcome (mRS 0–2).
In the IMS-III trial (which compared clinical outcome if intra-venous thrombolysis vs. intra-venous thrombolysis followed by mechanical thrombectomy), although halted because of “futility” after 2012, he said it “shows a positive effect of mechanical thrombectomy in patients with proven arterial occlusion.” Other trials included SYNTHESIS-EXP and MR Rescue.
In his conclusion, Söderman said there are many single-centre/device series showing around an 80% recanalisation rate and 50% good outcomes using mechanical thrombectomy.
There are three randomised controlled trials comparing various methods of intra-arterial treatment to intra-venous treatment. According to Söderman these three trials suffer from serious flaws, such as slow recruitment, inclusion of patients without major clot, obsolete devices and long time span until successful thrombectomy. He went on to day that there is currently no randomised controlled trial that compares intra-venous thrombolysis to mechanical thrombectomy with stentrievers with or without intra-venous thrombolysis, fulfilling the basic criteria:
- With proven clot in major vessel
- With Penumbra
- Within a time span when it is reasonable to expect any benefit from mechanical thrombectomy.
Although Söderman said that was no evidence to suggest one treatment over another, he noted that stentrievers are effective thrombectomy devices and in experienced hands are “fairly safe tools” that allow rapid thrombectomy.