Identifying Severe Stroke Patients Likely to Benefit From Thrombectomy Despite Delays of up to a Day

Abstract

Background and Purpose: Severe ischemic strokes caused by large vessel occlusion (LVO) are treatable up to 24 hours after onset. But not all patients will benefit either because the infarct enlarges too rapidly or because the patient is not at center that is capable of treatment. The purpose was to find biomarkers that reliably identify patients who are likely to benefit from intervention despite long delays .Methods: Thirty-eight acute ischemic stroke patients with LVO who did not undergo thrombolysis or thrombectomy had serial imaging with MRI at presentation and then at ~12 hours, ~1 day, & ~2 days after onset. Presenting clinical and neuroimaging predictors of a therapeutically auspicious ischemic core size (<50 ml) one day after stroke onset were identified.Results: Ischemic core initial growth rate (IGR) was the only independent predictor of functional outcome at 3 months (P=0.002), and a receiver operator characteristics (ROC) analysis revealed that an IGR of <5.4 ml/hr had a 95% sensitivity with a low (5.6%) false positive rate for identifying patients who would have an ischemic core of <50 ml at one day post ictus. Selection using an initial DWI lesion volume <37 ml was similarly powerful with a 90% sensitivity and a low false positive rate. Other imaging markers derived from CT scans were less effective, but may be more practical. Published reports of over 600 LVO ischemic stroke patients disclosed that about half met the highly favorable IGR criteria of <5.4 ml/hr at presentation. Conclusions:Ischemic core initial growth rates of <5.4ml/hr and initial ischemic cores of <37 ml are excellent biomarkers for selecting LVO patients that are likely to benefit from intervention despite long delays due to transfer to thrombectomy-capable stroke centers. Published accounts suggest that about half of all LVO stroke patients meet these criteria.

Late Thrombectomy in Clinical Practice

“…The numbers in the bars are percentages of patients who had each score; the percentages may not sum to 100 because of rounding. Scores on the modified Rankin scale range from 0 to 6, with 0 indicating no symptoms, 1 no clinically significant disability, 2 slight disability, 3 moderate disability, 4 moderately severe disability, 5 severe disability, and 6 death ies [20], we were not able to define a clear limit of the infarct volume, above which a good clinical outcome becomes unlikely. Based on imaging only, we are currently unable to accurately determine whether tissue is already irreversibly damaged or not.…”

Development and Clinical Application of a Deep Learning Model to Identify Acute Infarct on Magnetic Resonance Imaging

“…[1][2][3] Diffusion-weighted imaging (DWI) on magnetic resonance imaging (MRI) is highly accurate for diagnosing ischemic stroke shortly after symptom onset, 4 and the DWI lesion volume is used as a selection criterion for endovascular thrombectomy. [5][6][7][8][9] The selection of patients using MRI compared with CT doubles the likelihood of functional independence and results in fewer futile thrombectomies. 10,11 Machine learning, which involves a computer mathematical model learning to perform speci c tasks from existing data, is predicted to play an increasing role in clinical care.…”