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Optimized Management of Endovascular Treatment for Acute Ischemic Stroke
Published on: January 18, 2018
MRI vs CT for Baseline Imaging Evaluation in Acute Large Artery Ischemic Stroke: A Subanalysis of the SWIFT-DIRECT
Joachim Fladt1, Johannes Kaesmacher1, Thomas R Meinel1
1From the Stroke Center and Department of Neurology (J.F., U.F.), University Hospital Basel and University of Basel; University Institute of Diagnostic and Interventional Neuroradiology (J.K., J.G.), and Department of Neurology (T.R.M., U.F.), Inselspital, Bern University Hospital and University of Bern; CTU Bern (L.B.), University of Bern, Switzerland; Department of Neurology (D.S.), Helsinki University Hospital, University of Helsinki, Finland; Department of Neuroradiology (O.F.E.), Hospices Civils de Lyon; Department of Diagnostic and Therapeutic Neuroradiology (J.-F.A.), Centre Hospitalier Universitaire de Toulouse; Department of Diagnostic and Interventional Neuroradiology (H.D.), Centre Hospitalier Universitaire de Nantes, Nantes Université; Interventional and Diagnostic Neuroradiology (G.M.), CHU Bordeaux, University of Bordeaux; Department of Radiology (C.P.), CHU Rouen; Stroke Unit (S.R.), Department of Neurology, CHRU-Nancy, Université de Lorraine, France; Stroke Unit (M.R.), Department of Neurology, Hospital Vall d'Heborn, Barcelona, Spain; Department of Stroke and Diagnostic and Interventional Neuroradiology (B.L.), Foch Hospital, Suresnes, France; Department of Neuroradiology (P.P.), CHU Reims, France; Department of Neuroradiology (M.E.), University Medical Center Goettingen; Department of Neuroradiology (M.W.), University Hospital RWTH Aachen, Germany; Department of Neurology (M.B.), CHU Caen Normandie, University Caen Normandie, INSERM U1237, France; and Department of Neurology and Comprehensive Stroke Center (D.S.L.), David Geffen School of Medicine, University of California, Los Angeles.
Background And Objectives:
Whether MRI or CT is preferable for the evaluation of patients with suspected stroke remains a matter of debate, given that the imaging modality acquired at baseline may be a relevant determinant of workflow delays and outcomes with it, in patients with stroke undergoing acute reperfusion therapies.
Methods:
In this post hoc analysis of the SWIFT-DIRECT trial that investigated noninferiority of thrombectomy alone vs IV thrombolysis (IVT) + thrombectomy in patients with an acute ischemic anterior circulation large vessel occlusive stroke eligible to receive IVT within 4.5 hours after last seen well, we tested for a potential interaction between baseline imaging modality (MRI/MR-angiography [MRA] vs CT/CT-angiography [CTA]) and the effect of acute treatment (thrombectomy vs IVT + thrombectomy) on clinical and safety outcomes and procedural metrics (primary analysis). Moreover, we examined the association between baseline imaging modality and these outcomes using regression models adjusted for age, sex, baseline NIH Stroke Scale (NIHSS), occlusion location, and Alberta Stroke Program Early CT Score (ASPECTS) (secondary analysis). Endpoints included workflow times, the modified Rankin scale (mRS) score at 90 days, the rate of successful reperfusion, the odds for early neurologic deterioration within 24 hours, and the risk of symptomatic intracranial hemorrhage. The imaging modality acquired was chosen at the discretion of the treating physicians and commonly reflects center-specific standard procedures.
Results:
Four hundred five of 408 patients enrolled in the SWIFT-DIRECT trial were included in this substudy. Two hundred (49.4%) patients underwent MRI/MRA, and 205 (50.6%) underwent CT/CTA. Patients with MRI/MRA had lower NIHSS scores (16 [interquartile range (IQR) 12-20] vs 18 [IQR 14-20], p = 0.012) and lower ASPECTS (8 [IQR 6-9] vs 8 [IQR 7-9], p = 0.021) compared with those with CT/CTA. In terms of the primary analysis, we found no evidence for an interaction between baseline imaging modality and the effect of IVT + thrombectomy vs thrombectomy alone. Regarding the secondary analysis, MRI/MRA acquisition was associated with workflow delays of approximately 20 minutes, higher odds of functional independence at 90 days (adjusted odds ratio [aOR] 1.65, 95% CI 1.07-2.56), and similar mortality rates (aOR 0.73, 95% CI 0.36-1.47) compared with CT/CTA.
Discussion:
This post hoc analysis does not suggest treatment effect heterogeneity of IVT + thrombectomy vs thrombectomy alone in large artery stroke patients with different imaging modalities. There was no evidence that functional outcome at 90 days was less favorable following MRI/MRA at baseline compared with CT/CTA, despite significant workflow delays.
Trial Registration Information:
ClinicalTrials.gov Identifier: NCT03192332.
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