José G. Merino, MD

Translating research into practice: acute thrombectomy in stroke

Since the results of the MR CLEAN trial were announced at the World Stroke Congress in Istanbul last October, stroke physicians have been grappling with the question of how to interpret the panoply of positive trials of endovascular therapy (EVT) for acute stroke. Five trials published this year (MR CLEAN, ESCAPE, EXTEND-IA, SWIFT-PRIME, REVASCAT) show that thrombectomy, particularly when a stent retriever is used, is beneficial for patients with moderately severe or severe stroke if they have a relevant vascular occlusion, a small infarct core (seen as a relatively normal non-contrast CT) and, in some trials, a demonstrated large perfusion abnormality. Time to treatment is important, as the therapy is best for those patients treated soon after symptom onset, particularly if they also received standard IV tPA. 

When deciding how the findings from these trials apply to routine clinical situations, and when selecting patients for treatment, stroke neurologists must understand the differences in inclusion and exclusion criteria, analytical methods and response rates among the trials. Because of these differences, translating the benefits seen in these trials into clinical practice will be challenging. Because patients presenting to the ED outside the standard IV tPA window are now candidates for EVT, emergency department triage policies must be modified. Since EVT is effective for patients with proximal arterial occlusions, radiology departments will have to include vascular imaging in the standard pre-treatment imaging protocol). For EVT to be beneficial, interventional teams must be deployed quickly, sometimes before the diagnostic work up is completed or IV tPA administered, and more patients will have to be transferred to hospitals with an interventional team. Hospital systems and pre-hospital providers will have to develop new pathways, protocols and networks. National organizations will develop guidelines to help address these challenges, but local conditions and resources may constrain their implementation. A major challenge will be ensuring equitable access to care for all stroke patients, regardless of location.

As a stroke community, we have overcome similar challenges. When the NINDS tPA trial was published, the public and professional perception of stroke was that of therapeutic nihilism; since then we developed a very robust integrated stroke system of care that spans the pre-hospital to the rehabilitation stage and stroke patients are now triaged with the highest priority by paramedics, emergency physicians, radiologists, neurologists and others.

Stroke recently published a series of papers that put the research findings in context. These papers address the role of EVT from different professional and regional perspectives and clinicians and policy makers will find practical advice on measures to address the challenges discussed above. Seasoned and budding researchers will find the lists of unsolved research questions and areas of uncertainty valuable fodder for project ideas. The focus on different regions of the world brings attention to the chiasm in the level of care available in different areas of the world. Researchers and policymakers who work in international health may ponder whether access to EVT widen the gulf between the haves and have nots at a national and international level, at what can be done to mitigate these disparities

These are good times to be a stroke neurologist. The new knowledge we gain from these trials will benefit our patients. We are faced with the challenge of translating these research findings into practice, develop protocols and systems to ensure equitable timely access to effective beneficial therapies to as many eligible patients as possible, and build on the excitement of these results to seek even more effective therapies that apply to most stroke patients.