Since the publication of five large randomized controlled trials in 2015, intra-arterial treatment (IAT) by means of a stent retriever has become standard of care for patients with acute ischemic stroke due to an intracranial large vessel occlusion of the anterior circulation. Up until then, however, intravenous thrombolysis with alteplase (IVT) was the only proven reperfusion therapy for patients with acute ischemic stroke. Therefore the patients included in these trials also underwent IVT, unless contraindicated.

 
Currently it is unclear whether IVT is still of benefit to patients with a large vessel occlusion. Potential advantages include early recanalization, fewer required passes with a stent retriever, improved microvascular reperfusion and lysis of distal emboli. Potential disadvantages include low recanalization rates in large vessel occlusions, hemorrhagic complications, delay to treatment with IAT, thrombus fragmentation and neurotoxicity of alteplase itself.
The primary aim of the MR CLEAN-NO IV trial is to assess the effect of direct IAT compared with IVT followed by IAT on functional outcome in patients with acute ischemic stroke, caused by an anterior circulation occlusion that is confirmed by neuro-imaging.