Background It is uncertain if endovascular stroke therapy leads to improved clinical outcomes due to a paucity of data from randomized placebo-controlled trials. The aim of this study was to determine if MRI can be used to identify patients who are most likely to benefit from endovascular reperfusion. Methods Consecutive patients, scheduled to undergo endovascular therapy within 12 hours of stroke onset, were enrolled in a multi-center prospective cohort study. Aided by an automated image analysis software program, investigators interpreted the baseline MRI. They determined, prior to endovascular treatment, if the patient had an MRI profile (Target Mismatch) that suggested salvageable tissue was present. Reperfusion was assessed on an early follow-up MRI and defined as a >50% reduction in the volume of the baseline perfusion lesion. A favorable clinical response was defined as a ≥8 point improvement on the NIH Stroke Scale (NIHSS) between baseline and day 30 or an NIHSS score of 0–1 at 30 days. Findings Following endovascular therapy reperfusion occurred in 46 of 78 (59%) Target Mismatch patients and in 12 of 21 (57%) No Target Mismatch patients. The adjusted odds ratio for favorable clinical response associated with reperfusion was 8·5 (95% CI 2·6 – 28) in the Target Mismatch group and 0·2 (95% CI 0·0 – 1·6) in the No Target Mismatch group (p=0·003 for difference between odds ratios). Reperfusion was associated with an increased odds of good functional outcome at 90 days (OR is 5.2, 95% CI 1.4–19) and attenuation of infarct growth at 5 days (30 ml of median growth with reperfusion vs. 73 ml without reperfusion, p=0·01) in the Target Mismatch group but not in patients without Target Mismatch. Interpretation Target Mismatch patients who achieved early reperfusion following endovascular stroke therapy had more favorable clinical outcomes and less infarct growth. No association between reperfusion and favorable outcomes was present in patients without Target Mismatch. These data support a randomized controlled trial of endovascular treatment in patients with the Target Mismatch profile.

Increased blood pressure variability as measured by the SD, CV, and SV consistently predict worse neurologic outcomes as measured by follow-up mRS in patients with ischemic stroke treated with intra-arterial therapies. The SV is the strongest and most consistent predictor of worse outcomes at all time intervals.

No abstract

Background: The aim of DEFUSE 2 is to determine if predefined MRI profiles predict clinical and imaging outcomes following endovascular reperfusion therapy. Methods: This prospective, NIH funded, multi-center study enrolled consecutive acute stroke patients in whom an MRI scan could be obtained immediately prior to intra-arterial therapy. A follow-up MRI was performed within 12 hrs of completion of the procedure and again at 5 days. PWI and DWI lesion volumes were determined using a fully automated software program (RAPID). Lesion growth (infarct volume on 5 day FLAIR - baseline DWI volume) was compared for patients with and without the Target mismatch profile based on whether early reperfusion occurred. The Target mismatch profile was defined as PWI(Tmax>6s) / DWI >1.8, DWI <70 mL and PWI(Tmax>10s) <100 mL. Early reperfusion was defined as a >50% reduction in PWI volume following the procedure. The incidence and extent of DWI reversal was assessed and the fate of PWI lesions that were not reperfused was determined. Favorable clinical response was defined as an improvement in NIHSS ≥8 or 0-1 at 30 days. Results: This abstract represents a preliminary analysis of 71 of 101 patients who were treated with endovascular therapy (final results to be presented). Among the 54 patients with Target mismatch, early reperfusion was achieved in 70% and was associated with less infarct growth (relative median growth 210% vs. 450%, p=0.01) and a higher rate of favorable clinical response (OR=5.4; 95%CI 1.5-19.2). In patients without the Target mismatch profile (N= 13) early reperfusion was not associated with a reduction in infarct growth (relative median growth was 220% in both reperfusers and non-reperfusers; p=0.94) or an increased rate of favorable clinical response (OR=0.1; 95%CI 0.004-2.2). 96% of all voxels that were DWI positive at baseline were incorporated into the final infarct (assessed on the co-registered 5 day FLAIR); only 3 of 71 patients had FLAIR volumes that were smaller than the baseline DWI lesion (mean difference 3 mL). 80% of the voxels that had a PWI lesion (Tmax>6s) on the post-procedure scan were incorporated into the final infarct. The correlation between the union of the baseline DWI + early follow-up PWI lesion and the 5 day FLAIR volume was high (r=0.84; p< 0.0001). In 82% of the patients, the day 5 FLAIR volume was as at least as large as the union of the baseline DWI + early follow-up PWI lesion. Conclusion: Patients with the Target mismatch profile who achieve early reperfusion following intra-arterial therapy have less infarct growth and more favorable clinical outcomes. In contrast, no benefit of reperfusion was evident for non-Target mismatch patients. Baseline DWI lesions are virtually always fully incorporated into the final infarct volume, regardless of reperfusion. Tissue that remains hypoperfused (Tmax >6s) following endovascular therapy reliably progresses to infarction.

The ABC/2 method of volume estimation on CT perfusion is a reliable and efficient approach to determine infarct and penumbra volumes. The 1-CBV/MTT × 100% formula produces a mismatch percentage assisting providers in communicating the proportion of salvageable brain and guides therapy in the setting of patients with unclear time of onset with potentially salvageable tissue who can undergo mechanical retrieval or intraarterial thrombolytics.