Association of follow-up infarct volume with functional outcome in acute ischemic stroke: a pooled analysis of seven randomized trials.

Background: Follow-up infarct volume (FIV) has been recommended as an early indicator of treatment efficacy in patients with acute ischemic stroke. Questions remain about the optimal imaging approach for FIV measurement.
Objective: To examine the association of FIV with 90-day modified Rankin Scale (mRS) score and investigate its dependency on acquisition time and modality.
Methods: Data of seven trials were pooled. FIV was assessed on follow-up (12 hours to 2 weeks) CT or MRI. Infarct location was defined as laterality and involvement of the Alberta Stroke Program Early CT Score regions. Relative quality and strength of multivariable regression models of the association between FIV and functional outcome were assessed. Dependency of imaging modality and acquisition time (≤48 hours vs >48 hours) was evaluated.
Results: Of 1665 included patients, 83% were imaged with CT. Median FIV was 41 mL (IQR 14-120). A large FIV was associated with worse functional outcome (OR=0.88(95% CI 0.87 to 0.89) per 10 mL) in adjusted analysis. A model including FIV, location, and hemorrhage type best predicted mRS score. FIV of ≥133 mL was highly specific for unfavorable outcome. FIV was equally strongly associated with mRS score for assessment on CT and MRI, even though large differences in volume were present (48 mL (IQR 15-131) vs 22 mL (IQR 8-71), respectively). Associations of both early and late FIV assessments with outcome were similar in strength (ρ=0.60(95% CI 0.56 to 0.64) and ρ=0.55(95% CI 0.50 to 0.60), respectively).
Conclusions: In patients with an acute ischemic stroke due to a proximal intracranial occlusion of the anterior circulation, FIV is a strong independent predictor of functional outcome and can be assessed before 48 hours, oneither CT or MRI.
Competing Interests: Competing interests: MG reports grants from Covidien, personal fees from Covidien, during the conduct of the study; MG has a patent for diagnosing strokes (PCT/ CA2013/000761) licensed to GE Healthcare. BKM reports membership of the Steering and Executive Committee, ESCAPE trial that received support from Covidien Inc., Site Principal Investigator, SOCRATES Trial, sponsored by Astra Zeneca, honoraria from Penumbra Inc., a provisional patent 62/086077 for triaging systems in ischemic stroke, research funding from CIHR, HSFC, AIHS, HBI and the Faculty of Medicine, University of Calgary and board membership of QuikFlo Health Inc. WHvZ reports Honoraria; Modest; Stryker (paid to Institution). DWJD reports honoraria; Modest; Stryker (paid to Institution). PJM reports unrestricted grant funding for the EXTEND-IA trial to the Florey Institute of Neuroscience and Mental Health from Covidien (Medtronic), has served as an unpaid consultant to Codman Johnson and Johnson, his organization has received unrestricted research funding and grants from Codman Johnson and Johnson, Medtronic, and Stryker. AMD reports grant support and personal fees from Covidien (Medtronic). AD reports consultant/Advisory Board; Modest; Medtronic Neurovascular (Steering Committee STAR). CBLMM reports speakers' Bureau; Modest; Stryker (paid to institution). GAD reports grants from the Australian National Health & Medical Research Council, non-financial support from, and has served on advisory boards for Boehringer Ingelheim, Astra Zeneca, Bristol Meyers-Squibb, Merck Sharp & Dohme outside the submitted work. BCVC reports research support from the National Health and Medical Research Council of Australia (GNT1043242, GNT1035688), Royal Australasian College of Physicians, Royal Melbourne Hospital Foundation, National Heart Foundation, National Stroke Foundation of Australia and unrestricted grant funding for the EXTEND-IA trial to the Florey Institute of Neuroscience and Mental Health from Covidien (Medtronic). MDH reports unrestricted grant funding for the ESCAPE trial to University of Calgary from Covidien (Medtronic), and active/in-kind support consortium of public/charitable sources (Heart & Stroke Foundation, Alberta Innovates Health Solutions, Alberta Health Services) and the University of Calgary (Hotchkiss Brain Institute, Departments of Clinical Neurosciences and Radiology, and Calgary Stroke Program); personal fees from Merck, non-financial support from Hoffmann-La Roche Canada Ltd, outside the submitted work; MDH has a patent Systems and Methods for Assisting in Decision-Making and Triaging for Acute Stroke Patients pending to US Patent office Number: 62/086,077 and owns stock in Calgary Scientific Incorporated, a company that focuses on medical imaging software. AMMB and HAM own stock in Nico.lab, a company that focuses on medical imaging software. TGJ has consulted for Codman Neurovascular and Neuravi, holds stock in Silk Road and Blockade; has acted as an unpaid consultant to Stryker as PI of the DAWN trial and served as an unpaid member of a Medtronic Advisory Board. SMD reports lecture fees from Covidien (Medtronic). ScB acts as consultant for Medtronic. GWA reports equity and consulting for iSchemaView (imaging software) and consulting for Medtronic.
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