Background: Intravenous thrombolysis (IVT) and intra-arterial thrombolysis (IAT) have been shown to be effective treatments for acute stroke in controlled randomized trials and meta-analyses. However, prospective studies comparing IVT and IAT have not been performed, and it is not known which patients benefit more from IVT or IAT. Non-invasive neurovascular imaging techniques such as magnetic resonance angiography (MRA) or computed tomography angiography (CTA) have the potential to improve patient selection for the optimal mode of thrombolytic therapy and provide data of pre-treatment neurovascular findings of patients treated with IVT. IAT series have identified several prognostic factors for favourable or poor outcome predictors such as vessel recanalization, location of the vascular occlusion or NIHSS at admission. Additional studies have shown that recanalization rates in patients with central ves-sel occlusions such as middle cerebral artery (MCA) main stem or MCA main branch or basilar artery (BA) is higher when treated with IAT compared to IVT. Therefore, the investigators hypothesize that IAT might be more efficacious in these patients.

Objective: Prospective observational multicenter registry with the following aims: To compare the safety and efficacy of IAT and IVT in patients with acute ischemic stroke. To improve safety of IAT and IVT by monitoring the in-hospital management.

Methods: Consecutive patients with acute ischemic stroke who are treated with IVT or IAT within 6 hours of symptom onset in a Swiss stroke unit will be eligible for this registry. Patients are given either intravenous rt-PA or receive IAT such as intra-arterial urokinase, intra-arterial rt-PA or mechanical endovascular recanalization techniques. Patient involvement in the registry shall not influence any treatment decision. Patients will undergo a complete diagnostic work up including a clinical neurological examination using the National Institutes of Health Stroke Scale (NIHSS) score on admission, laboratory examination, brain and neurovascular imaging, echocardiography, 24-hours ECG to determine stroke etiology using the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. The treating physician will initiate secondary prevention of stroke as soon as possible. All patients will be examined by CT and CTA or MRI and MRA on day 1 and in any case of clinical deterioration to exclude intracranial haemorrhage and to assess recanalization of the occluded vessel (using the thrombolysis in myocardial infarction (TIMI) grading system). Clinical outcome will be evaluated on day 1 and at 3 months using the National Institute of Health Stroke Scale (NIHSS) score, modified Rankin Scale score (mRS), Barthel Index (BI), and assessing adverse events and quality of life. The proportion of patients with favourable outcome (mRS 0 to 2) at 3 months after IVT and IAT will serve as the primary outcome measure. In addition, subgroup analyses will be performed stratified by NIHSS, location of vessel occlusion, time to hospital admission and time to treatment. Secondary outcome measures will include quality of life and the proportion of patients with an excellent outcome (mRS 0 or 1) at 3 months, BI 75 to 100 at 3 months, mortality at 3 months, rapid neurological improvement during the first 24 hours, complete or partial recanalization, and symptomatic intracranial haemorrhage.