Different mismatch concepts for MRI-guided thrombolysis in unknown onset stroke.

Abstract

To explore the prevalence of the perfusion-weighted imaging (PWI) - diffusion-weighted imaging (DWI) mismatch and response to intravenous thrombolysis in the WAKE-UP trial. We performed a prespecified post-hoc analysis of ischemic stroke patients screened for DWI - fluid-attenuated inversion recovery (FLAIR) mismatch in WAKE-UP who underwent PWI. We defined PWI-DWI mismatch as ischemic core volume < 70 ml, mismatch volume > 10 ml and mismatch ratio > 1.2. Primary efficacy endpoint was a modified Rankin Scale score of 0-1 at 90 days, adjusted for age and symptom severity. Of 1,362 magnetic resonance imaging (MRI) screened patients, 431 underwent PWI. Of these, 57 (13%) had a double mismatch, 151 (35%) only a DWI-FLAIR mismatch and 54 (13%) only a PWI-DWI mismatch. DWI-FLAIR mismatch was more prevalent than PWI-DWI mismatch (48%; 95% CI 43%-53% vs 26%; 95% CI 22%-30%, p < 0.0001). Screening for either one of the mismatch profiles resulted in a yield of 61% (95% CI 56%-65%). Prevalence of PWI-DWI mismatch was similar in patients with (27%) or without (24%) DWI-FLAIR mismatch (p = 0.52). In an exploratory analysis in the small subgroup of 208 randomized patients with PWI, PWI-DWI mismatch status did not modify the treatment response (p for interaction = 0.73). Evaluating both the DWI-FLAIR and PWI-DWI mismatch pattern in patients with unknown time of stroke onset will result in the highest yield of thrombolysis treatment. The treatment benefit of alteplase in patients with a DWI-FLAIR mismatch seems not merely driven by the presence of a PWI-DWI mismatch, although this analysis was underpowered. This article is protected by copyright. All rights reserved.