***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: BACKGROUND In patients with ischemic stroke , endovascular treatment results in a higher rate of recanalization of the affected cerebral artery than systemic intravenous thrombolytic therapy . However , comparison of the clinical efficacy of the two approaches is needed . METHODS We r and omly assigned 362 patients with acute ischemic stroke , within 4.5 hours after onset , to  endovascular therapy ( intraarterial thrombolysis with recombinant tissue plasminogen activator [ t-PA ] , mechanical clot disruption or retrieval , or a combination of these approaches ) or intravenous t-PA . Treatments were to be given as soon as possible after r and omization . The primary outcome was survival free of disability ( defined as a modified Rankin score of 0 or 1 on a scale of 0 to 6 , with 0 indicating no symptoms , 1 no clinical ly significant disability despite symptoms , and 6 death ) at 3 months . RESULTS A total of 181 patients were assigned to receive endovascular therapy , and 181 intravenous t-PA .  The median time from stroke onset to the start of treatment was 3.75 hours for endovascular therapy and 2.75 hours for intravenous t-PA ( P<0.001 ) . At 3 months , 55 patients in the endovascular-therapy group ( 30.4 % ) and 63 in the intravenous t-PA group ( 34.8 % ) were alive without disability ( odds ratio adjusted for age , sex , stroke severity , and atrial fibrillation status at baseline , 0.71 ; 95 % confidence interval , 0.44 to 1.14 ; P=0.16 ) . Fatal or nonfatal symptomatic intracranial hemorrhage within 7 days occurred in 6 % of the patients in each group , and there were no significant differences between groups in the rates of other serious adverse events or the case fatality rate . CONCLUSIONS The results of this trial in patients with acute ischemic stroke indicate that endovascular therapy is not superior to st and ard treatment with intravenous t-PA . ( Funded by the Italian Medicines Agency , Clinical Trials.gov number , NCT00640367 . ) Background Endovascular or intra-arterial treatment ( IAT ) increases the likelihood of recanalization in patients with acute ischemic stroke caused by a proximal intracranial arterial occlusion . However , a beneficial effect of IAT on functional recovery in patients with acute ischemic stroke remains unproven . The aim of this study is to assess the effect of IAT on functional outcome in patients with acute ischemic stroke . Additionally , we aim to assess the safety of IAT , and the effect on recanalization of different mechanical treatment modalities . Methods / design A multicenter r and omized clinical trial with blinded outcome assessment . The active comparison is IAT versus no IAT . IAT may consist of intra-arterial thrombolysis with alteplase or urokinase , mechanical treatment or both . Mechanical treatment refers to retraction , aspiration , sonolysis , or use of a retrievable stent ( stent-retriever ) . Patients with a relevant intracranial proximal arterial occlusion of the anterior circulation , who can be treated within 6 hours after stroke onset , are eligible . Treatment effect will be estimated with ordinal logistic regression ( shift analysis ) ; 500 patients will be included in the trial for a power of 80 % to detect a shift leading to a decrease in dependency in 10 % of treated patients . The primary outcome is the score on the modified Rankin scale at 90 days . Secondary outcomes are the National Institutes of Health stroke scale score at 24 hours , vessel patency at 24 hours , infa rct size on day 5 , and the occurrence of major bleeding during the first 5 days . Discussion If IAT leads to a 10 % absolute reduction in poor outcome after stroke , careful implementation of the intervention could save approximately 1 % of all new stroke cases from death or disability annually . Trial registration NTR1804 ( 7 May 2009)/IS RCT N10888758 ( 24 July 2012 ) BACKGROUND Trials of endovascular therapy for ischemic stroke have produced variable results . We conducted this study to test whether more advanced imaging selection , recently developed devices , and earlier intervention improve outcomes . METHODS We r and omly assigned patients with ischemic stroke who were receiving 0.9 mg of alteplase per kilogram of body weight less than 4.5 hours after the onset of ischemic stroke either to undergo endovascular thrombectomy with the Solitaire FR ( Flow Restoration ) stent retriever or to continue receiving alteplase alone .  All the patients had occlusion of the internal carotid or middle cerebral artery and evidence of salvageable brain tissue and ischemic core of less than 70 ml on computed tomographic ( CT ) perfusion imaging . The co primary outcomes were reperfusion at 24 hours and early neurologic improvement ( ≥8-point reduction on the National Institutes of Health Stroke Scale or a score of 0 or 1 at day 3 ) . Secondary outcomes included the functional score on the modified Rankin scale at 90 days . RESULTS The trial was stopped early because of efficacy after 70 patients had undergone r and omization ( 35 patients in each group ) . The percentage of ischemic territory that had undergone reperfusion at 24 hours was greater in the endovascular-therapy group than in the alteplase-only group ( median , 100 % vs. 37 % ; P<0.001 ) . Endovascular therapy , initiated at a median of 210 minutes after the onset of stroke , increased early neurologic improvement at 3 days ( 80 % vs. 37 % , P=0.002 ) and improved the functional outcome at 90 days , with more patients achieving functional independence ( score of 0 to 2 on the modified Rankin scale , 71 % vs. 40 % ; P=0.01 ) . There were no significant differences in rates of death or symptomatic intracerebral hemorrhage . CONCLUSIONS In patients with ischemic stroke with a proximal cerebral arterial occlusion and salvageable tissue on CT perfusion imaging , early thrombectomy with the Solitaire FR stent retriever , as compared with alteplase alone , improved reperfusion , early neurologic recovery , and functional outcome . ( Funded by the Australian National Health and Medical Research Council and others ; EXTEND-IA Clinical Trials.gov number , NCT01492725 , and Australian New Zeal and Clinical Trials Registry number , ACTRN12611000969965 . ) Rationale Multimodal imaging has the potential to identify acute ischaemic stroke patients most likely to benefit from late recanalization therapies . Aims The general aim of the Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy Trial is to investigate whether multimodal imaging can identify patients who will benefit substantially from mechanical embolectomy for the treatment of acute ischaemic stroke up to eight-hours from symptom onset . Design Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy is a r and omized , controlled , blinded- outcome clinical trial . Population studied Acute ischaemic stroke patients with large vessel intracranial internal carotid artery or middle cerebral artery M1 or M2 occlusion enrolled within eight-hours of symptom onset are eligible . The study sample size is 120 patients . Study intervention Patients are r and omized to endovascular embolectomy employing the Merci Retriever ( Concentric Medical , Mountain View , CA ) or the Penumbra System ( Penumbra , Alameda , CA ) vs. st and ard medical care , with r and omization stratified by penumbral pattern . Outcomes The primary aim of the trial is to test the hypothesis that the presence of substantial ischaemic penumbral tissue visualized on multimodal imaging ( magnetic resonance imaging or computed tomography ) predicts patients most likely to respond to mechanical embolectomy for treatment of acute ischaemic stroke due to a large vessel , intracranial occlusion up to eight-hours from symptom onset . This hypothesis will be tested by analysing whether pretreatment imaging pattern has a significant interaction with treatment as a determinant of functional outcome based on the distribution of scores on the modified Rankin Scale measure of global disability assessed 90 days poststroke . Nested hypotheses test for ( 1 ) treatment efficacy in patients with a penumbral pattern pretreatment , and ( 2 ) absence of treatment benefit ( equivalency ) in patients without a penumbral pattern pretreatment . An additional aim will only be tested if the primary hypothesis of an interaction is negative : that patients treated with mechanical embolectomy have improved functional outcome vs. st and ard medical management ESCAPE is a prospect i ve , multicenter , r and omized clinical trial that will enroll subjects with the following main inclusion criteria : less than 12 h from symptom onset , age > 18 , baseline NIHSS > 5 , ASPECTS score of > 5 and CTA evidence of carotid T/L or M1 segment MCA occlusion , and at least moderate collaterals by CTA . The trial will determine if endovascular treatment will result in higher rates of favorable outcome compared with st and ard medical therapy alone . Patient population s that are eligible include those receiving IV tPA , tPA ineligible and unwitnessed onset or wake up strokes with 12 h of last seen normal . The primary end-point , based on intention-to-treat criteria is the distribution of modified Rankin Scale scores at 90 days assessed using a proportional odds model . The projected maximum sample size is 500 subjects . R and omization is stratified under a minimization process using age , gender , baseline NIHSS , baseline ASPECTS ( 8–10 vs. 6–7 ) , IV tPA treatment and occlusion location ( ICA vs. MCA ) as covariates . The study will have one formal interim analysis after 300 subjects have been accrued . Secondary end-points at 90 days include the following : mRS 0–1 ; mRS 0–2 ; Barthel 95–100 , EuroQOL and a cognitive battery . Safety outcomes are symptomatic ICH , major bleeding , contrast nephropathy , total radiation dose , malignant MCA infa rct ion , hemicraniectomy and mortality at 90 days BACKGROUND We aim ed to assess the safety and efficacy of thrombectomy for the treatment of stroke in a trial embedded within a population -based stroke reperfusion registry . METHODS During a 2-year period at four centers in Catalonia , Spain , we r and omly assigned 206 patients who could be treated within 8 hours after the onset of symptoms of acute ischemic stroke to receive either medical therapy ( including intravenous alteplase when eligible ) and endovascular therapy with the Solitaire stent retriever ( thrombectomy group ) or medical therapy alone ( control group ) . All patients had confirmed proximal anterior circulation occlusion and the absence of a large infa rct on neuroimaging . In all study patients , the use of alteplase either did not achieve revascularization or was contraindicated . The primary outcome was the severity of global disability at 90 days , as measured on the modified Rankin scale ( ranging from 0 [ no symptoms ] to 6 [ death ] ) . Although the maximum planned sample size was 690 , enrollment was halted early because of loss of equipoise after positive results for thrombectomy were reported from other similar trials . RESULTS Thrombectomy reduced the severity of disability over the range of the modified Rankin scale ( adjusted odds ratio for improvement of 1 point , 1.7 ; 95 % confidence interval [ CI ] , 1.05 to 2.8 ) and led to higher rates of functional independence ( a score of 0 to 2 ) at 90 days ( 43.7 % vs. 28.2 % ; adjusted odds ratio , 2.1 ; 95 % CI , 1.1 to 4.0 ) . At 90 days , the rates of symptomatic intracranial hemorrhage were 1.9 % in both the thrombectomy group and the control group ( P=1.00 ) , and rates of death were 18.4 % and 15.5 % , respectively ( P=0.60 ) . Registry data indicated that only eight patients who met the eligibility criteria were treated outside the trial at participating hospitals . CONCLUSIONS Among patients with anterior circulation stroke who could be treated within 8 hours after symptom onset , stent retriever thrombectomy reduced the severity of post-stroke disability and increased the rate of functional independence . ( Funded by Fundació Ictus Malaltia Vascular through an unrestricted grant from Covidien and others ; REVASCAT Clinical Trials.gov number , NCT01692379 . ) BACKGROUND Among patients with acute ischemic stroke due to occlusions in the proximal anterior intracranial circulation , less than 40 % regain functional independence when treated with intravenous tissue plasminogen activator ( t-PA ) alone . Thrombectomy with the use of a stent retriever , in addition to intravenous t-PA , increases reperfusion rates and may improve long-term functional outcome . METHODS We r and omly assigned eligible patients with stroke who were receiving or had received intravenous t-PA to continue with t-PA alone ( control group ) or to undergo endovascular thrombectomy with the use of a stent retriever within 6 hours after symptom onset  ( intervention group ) . Patients had confirmed occlusions in the proximal anterior intracranial circulation and an absence of large is 
    Output:
    
In pooled analysis endovascular treatment , including thrombectomy , was associated with a higher proportion of patients experiencing good ( modified Rankin scale scores ≤2 ) and excellent ( scores ≤1 ) outcomes 90 days after stroke , without differences in mortality or rates for symptomatic intracranial haemorrhage , compared with patients r and omised to medical care alone , including intravenous rt-PA .
The more recent studies ( seven r and omised controlled trials , published or presented in 2015 ) proved better suited to evaluate the effect of adjunctive intra-arterial mechanical thrombectomy on its index disease owing to more accurate patient selection , intravenous rt-PA being administered at a higher rate and earlier , and the use of more efficient thrombectomy devices .
Moderate to high quality evidence suggests that compared with medical care alone in a selected group of patients endovascular thrombectomy as add-on to intravenous thrombolysis performed within six to eight hours after large vessel ischaemic stroke in the anterior circulation provides beneficial functional outcomes , without increased detrimental effects .