DWI-FLAIR Mismatch-guided IVT is Safe and Effective in Treatment of AIS Beyond 4.5 Hours

Background: Perfusion or clinical mismatch imaging is useful in selecting patients with acute ischemic stroke (AIS) for reperfusion therapies beyond 4.5 hours. These techniques are expensive, technically difficult, and therefore unavailable in most settings. The diffusion weighted imaging-fluid attenuated inversion recovery (DWI-FLAIR) mismatch pattern has been studied only in wake-up stroke/stroke with unclear time of onset but not in AIS patients with clear time of onset of more than 4.5 hours. This study assesses routinely available magnetic resonance imaging (MRI) DWI-FLAIR sequences for selecting AIS patients for intravenous thrombolytic therapy (IVT) beyond 4.5 hours of the witnessed onset of symptoms. Aim: To study the clinical spectrum and outcome of patients with AIS who received IVT based on the DWI-FLAIR mismatch seen beyond 4.5 hours of symptom onset. Methods, Observation, and Results: Retrospective analysis was performed on 10 patients who received IVT for AIS beyond 4.5 hours and had an MRI DWI-FLAIR mismatch. In cohort study, 60% patients were males, with the median age of 59 years, the median baseline National Institutes of Health Stroke Scale (NIHSS) score of 10 (range 7 to 15), and the median time from the onset to imaging of 412.5 minutes. Within 24 hours of thrombolysis, improvement of >4 points in NIHSS was seen in 7 out of 10 (70%) patients, and at the modified Rankin scale, the score of 0 to 1 was noted at 3 months in 8 out of 10 (80%) patients. Neuroimaging at 24 hours showed no intracerebral bleed. Discussion and Conclusion: DWI-FLAIR mismatch-guided IVT is safe and effective in patients with AIS beyond 4.5 hours of the onset of symptoms. More studies are recommended to confirm these findings.