Mechanical Thrombectomy in the Late Presentation of Anterior Circulation Large Vessel Occlusion Stroke: A Guideline From the Society of Vascular and Interventional Neurology Guidelines and Practice Standards Committee.

Background and Purpose: Recent clinical trials investigating endovascular therapy (EVT) in the extended time window have opened new treatment paradigms for late-presenting patients with large vessel occlusion (LVO) stroke. The aim of this guideline is to provide up to date recommendations for the diagnosis, selection, and medical or endovascular treatment of patients with LVO presenting in the extended time window. Methods: The Society of Vascular & Interventional Neurology (SVIN) Guidelines and Practice Clinical Standards (GAPS) committee assembled a writing group and recruited interdisciplinary experts to review and evaluate the current literature. Recommendations were assigned by the writing group using the SVIN-GAPS Class of Recommendation/Level of Evidence algorithm and SVIN GAPS guideline format. The final guideline was approved by all members of the writing group, the GAPS committee, and the SVIN board of directors. Results: Literature review yielded three high quality randomized trials and several observational studies that have been extracted to derive the enclosed summary recommendations. In patients with LVO presenting in the 6-to-24-hour window, and with clinical imaging mismatch as defined by the DAWN and DEFUSE 3 studies, EVT is recommended. Non contrast CT can be used to evaluate infarct size as sole imaging modality for patient selection, particularly when access to CT perfusion or MRI is limited, or if their performance would incur substantial delay to treatment. In addition, several clinical questions were reviewed based on the available evidence and consensus grading. Conclusion: These guidelines provide practical recommendations based on recent evidence on the diagnosis, selection, and treatment of patients with LVO stroke presenting in the extended time window.