Large Stroke Therapy Evaluation

Overview

Stroke represents the fourth leading cause of death in industrialized nations, after heart disease, cancer, and chronic lower respiratory disease. The overall burden of stroke will rise dramatically in the next 20 years due to an ageing population. Approximately one-quarter of the patients suffering a stroke die within one year after the initial event and stroke is a leading cause of serious long-term disability. Acute ischemic stroke (AIS) due to large vessel occlusion (LVO) is a potentially devastating event, with a poor prognosis in the absence of timely revascularization. Whether in patients with large anterior circulation stroke, direct mechanical intervention is equally effective, superior or inferior to bridging thrombolysis remains a matter of debate. Thus, this procedure, is now the recommended standard of care for selective patients with LVO in the anterior circulation. When performed with newer generation devices (mainly stent retrievers), more stringent imaging selection criteria and more efficient workflow than in previous trials, significantly reduces disability rates after AIS caused by LVO in the anterior circulation. The STAIR (Stroke Treatment Academic Industry Roundtable) meeting aims to advance acute stroke therapy development through collaboration between academia, industry, and regulatory institutions. In pursuit of this goal and building on the available level I evidence of benefit from endovascular therapy (EVT) in large vessel occlusion stroke, STAIR IX consensus recommendations were developed that outline priorities for future research in EVT.

The LASTE hypothesis is that patient harbouring a large ischemic core stroke at presentation, may still benefit from mechanical thrombectomy, given the very poor natural history of patient managed by a standalone medical therapy. The threshold of ASPECTS 5 to set a benefit for treatment was inspired by initial large medical trials using IV t-PA25-27 (Samurai-CT ALBERTA Score IV cohort). In the paradigm of acute and complete reperfusion, radiographic infarct stroke volume may be partially reversible and thus the resulting final infarct may be smaller compared to the one in non-re-perfused patients who will consequently have poorer clinical outcomes. By now, large core patients defined as ASPECTS 0-5 were excluded from most randomized clinical trials resulting in a lack of unequivocal evidence of benefit in this patient population. Analyses of several prospective cohorts suggest signals of benefit in favor of thrombectomy in patients with large baseline core. In the prospective cohort ETIS, LAPERGUE et al reported a rate of good outcome of 34% in the subgroup of patient with ASPECT 4-5. In the prospective cohort analysis RECOST, a mean mRS score of 34% in a group of patient presenting ASPECT 0-5 treated with mechanical thrombectomy, versus 9% of good outcome in the medical group, suggesting a benefit to treat LVO harbouring a large core. The strongest argument in favor of benefit of EVT even in patients with large core is provided by the six completed randomized endovascular stroke trials. These trials did prove that Combined Approach Mechanical + IV t-PA, is superior to standalone IV lytics, mRs score ≤ 2 ranging from 33% and up to 72%, but Large Core Infarction were largely excluded. Nonetheless a pooled analysis of these trials revealed that a minority of patients with large baseline core were still randomized. In MR CLEAN study, despite no exclusion criteria defined in the initial protocol, the median ASPECT score of the cohort was 9 out of 10. In SWIFT-PRIME study, the mean ASPECT score of the cohort was 7, and in REVASCAT study it was 6.8. The LASTE protocol "Large Stroke Therapy Evaluation" aims to study the efficacy and safety of mechanical thrombectomy in the acute phase of cerebral infarction less than 7 hours for patients with a large volume of necrosis defined by a score ASPECT from 0 to 5. The patients will be followed 6 months after the stroke.