FRONTIER-AP-X: Randomized controlled trial of endovascular versus standard medical therapy for stroke with medium sized vessel occlusion

Patients randomised to the thrombectomy arm will have clot extraction by Stent retriever or aspiration catheter. This will be performed by certified interventional radiologist. In brief, it involves performing digital subtraction angiography, navigating the catheter to the site of the clot and performing the extraction. The procedure is anticipated to be around 1 hour but can take up to 2 hours on average. The standard care arm is alteplase or tenecteplase within 4.5 hours and between 4.5 - 9 hours, it’s alteplase or tenecteplase or best medical therapy according to the local guidelines. Post-intervention: A non-contrast Computed Tomography (CT) and CT Angiography will be performed 24 to 48 hr post intervention. At the investigator’s discretion, a repeat CT Perfusion or Magnetic Resonance Imaging (MRI) may be performed at 24 to 48 hr. For MRI (if used for baseline selection and at 24 to 48hrs), an initial scout view will be followed by isotropic Difiusion-weighted Imaging/DWI (created from DWI images obtained with diffusion sensitizing gradients applied in 3 orthogonal planes) using b values between 0 sec/mm2, equivalent to a T2-weighted image, and 1000 sec/mm2. Whole brain imaging will use 25 contiguous axial slices each 5 mm in thickness. The imaging time for DWI is approximately 3 minutes. Time of Flight MR Angiography will be obtained to determine the presence or absence of medium vessel occlusion (MVO). A T2*-weighted gradient echo sequence will be performed to assess for presence of intracerebral haemorrhage (ICH). A FLAIR sequence is also acquired. This protocol is identical between the acute and sub-acute (24 h) imaging.