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Too much guidance
  1. David Fiorella1,
  2. J Mocco2,
  3. Adam S Arthur3,
  4. Sean Lavine4,
  5. Felipe C Albuquerque5,
  6. Don Frei6,
  7. Raymond D Turner7,
  8. Aquilla Turk8,
  9. Adnan H Siddiqui9,
  10. William J Mack10,
  11. Andrei Alexandrov11,
  12. Joshua A Hirsch12,
  13. Robert W Tarr13
  1. 1Department of Neurosurgery, State University of New York at Stony Brook, Stony Brook, New York, USA
  2. 2Mt Sinai Hospital, NYC, New York, USA
  3. 3University of Tennessee, Semmes-Murphey Neurologic and Spine Clinic, Memphis, Tennessee, USA
  4. 4New York-Presbyterian Hospital, New York, USA
  5. 5Division of Neurological Surgery, Barrow Neurological Institute, Phoenix, Arizona, USA
  6. 6Department of Interventional Neuroradiology, Radiology Imaging Associates, Englewood, Colorado, USA
  7. 7Department of Neurosciences, Medical University of South Carolina, Mount Pleasant, South Carolina, USA
  8. 8Medical University of South Carolina, Charleston, South Carolina, USA
  9. 9Departments of Neurosurgery and Radiology and Toshiba Stroke Research Center, University at Buffalo, State University of New York, Buffalo, New York, USA
  10. 10Department of Neurosurgery, University of Southern California, Los Angeles, California, USA
  11. 11Department of Neurology, University of Tennessee, Memphis, Tennessee, USA
  12. 12NeuroEndovascular Program, Massachusetts General Hospital, Boston, Massachusetts, USA
  13. 13Department of Radiology, University Hospitals Case Medical Center, Ohio, Ohio, USA
  1. Correspondence to Dr David Fiorella, Department of Neurosurgery, State University of New York at Stony Brook, Stony Brook, NY 11794-8122, USA; David.Fiorella{at}

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The unambiguous benefit of thrombectomy in patients with emergent large vessel occlusion (ELVO) has now been demonstrated in five multicenter, prospective, randomized controlled trials.1–5 These trials ended just months after three randomized controlled trials had shown no benefit for thrombectomy.6–8

The positive trials differ from the negative trials in three important ways. First, modern thrombectomy devices (primarily stent retrievers) were used in each of the positive trials. Patients in the negative trials were primarily treated with intra-arterial thrombolytic infusions and the MERCI device, which have been shown to be much less effective in achieving an effective revascularization. Second, the positive trials mandated vascular imaging to confirm large vessel occlusion before enrollment. Confirmation of large vessel occlusion was a requirement for only the smallest of the earlier negative trials. A subsequent subgroup analysis of the largest trial indicated that for those patients with confirmation of large vessel occlusion there appeared to be a benefit for thrombectomy. Third, with experience derived from prior studies, the exclusion of patients with large areas of completed infarct and little likelihood of improving after endovascular therapy was recognized to be of critical importance. In three of the five positive trials, advanced imaging applications were incorporated into the screening process to help investigators exclude patients with large areas of completed infarction, and the others used either a ‘grey principle’ or the ASPECTS score to allow proceduralists to screen patients before enrollment. There were other differences in the design of the positive trials, but these three major differences, largely consistent across trials, accounted for their overwhelming and uniform positivity.

These data have resulted …

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