Indications for Mechanical Thrombectomy-Too Wide or Too Narrow?

The indications for mechanical thrombectomy (MT) have expanded since the American Heart Association/American Stroke Association reported its first guidelines for MT in 2013. Multiple subsequent randomized clinical trials of MT have proved its efficacy, including the DAWN (DWI [diffusion weighted imaging] or CTP [computed tomography perfusion] Assessment with Clinical Mismatch in the Triage of Wake-up and Late Presenting Strokes Undergoing Neurointervention with Trevo) and DEFUSE-3 (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke-3) trials. The current guidelines from the American Heart Association/American Stroke Association provide class I support for the use of MT for the following indications: 1) internal carotid artery (ICA)/M1 middle cerebral artery (MCA) occlusion, symptom onset <6 hours, National Institutes of Health Stroke Scale score of ≥6, Alberta Stroke Program Early Computed Tomography Score of ≥6; and 2) large vessel occlusions in the anterior circulation, symptom onset 6-16 hours, and meeting the DAWN or DEFUSE-3 eligibility criteria. Class IIa evidence is also available for the use of MT for large vessel occlusions in the anterior circulation, symptom onset 16-24 hours, and meeting other DAWN eligibility criteria. In clinical practice, these class I and IIa indications for MT have been well followed. However, many other potential indications are available, including 1) M2 or M3 MCA occlusion, symptom onset <6 hours; 2) Alberta Stroke Program Early Computed Tomography Score <6, ICA or M1 MCA occlusion, symptom onset <6 hours; 3) National Institutes of Health Stroke Scale score <6, ICA or M1 occlusion, symptom onset <6 hours; 4) tandem occlusions; and 5) posterior circulation occlusion <6 hours. The present review analyzed the available data to provide support for further prospective clinical trials regarding these potential indications.