Rationale Ischaemic stroke is often caused by embolic occlusion of proximal intracranial arteries. The effect of intravenous alteplase is limited in these patients. Endovascular treatment increases the likelihood of recanalisation, but the effect of treatment on functional outcome is not certain.

Aim The main purpose of the Multicentre Randomised Clinical trial of Endovascular treatment for acute ischaemic stroke in the Netherlands (MR CLEAN) is to assess the effect on functional outcome and safety of endovascular treatment in patients with a proximal intracranial arterial occlusion in the anterior circulation.

Design MR CLEAN is a pragmatic phase III multicentre randomised clinical trial with blinded outcome assessment. The intervention contrast is endovascular treatment with trombolytics (urokinase or alteplase) and/or mechanical trombectomy versus no endovascular treatment. The choice of endovascular treatment modality for each patient is left to the discretion of the local investigator and treating physicians. Background medical management is delivered according to national standards and guidelines. It may include intravenous alteplase within the first 4.5 hours after onset.

Outcomes The primary outcome is the score on the modified Rankin scale (mRS) 90 days after inclusion in the study. Secondary outcomes are the NIHSS score at 24 hours, vessel patency, infarct size, and the occurrence of major bleeding. The randomisation will be stratified for use of intravenous alteplase, planned treatment modality (intra-arterial thrombolysis, mechanical trombectomy or both) treatment centre and stroke severity. The effect of treatment will be estimated by means of the ordinal logistic regression (shift analysis). In total, 500 patients will be included in the trial.

Discussion The trial is going well. We estimated that inclusion of patients will take 4 years. The trial has started in December 2010. As of November 2012, 12 participating centres are active and 234 patients have been included.

Disclosures C. Majoie: 1; C; Dutch Heart Foundation. 6; C; EV3, Penumbra, Angiocare, Top Medical, Lamepro/Medac. O. Berkhemer: None. D. Beumer: None. R. van Oostenbrugge: None. P. Fransen: None. W. van Zwam: None. A. van der Lugt: None. Y. Roos: None. D. Dippel: 1; C; Dutch Heart Foundation. 6; C; EV3, Penumbra, Angiocare, Top Medical, Lamepro/Medac.