Peggy Nguyen, MD

Al-Ajlan FS, Goyal M, Demchuk AM, Minhas P, Sabiq F, Assis Z, et al. Intra-Arterial Therapy and Post-Treatment Infarct Volumes: Insights From the ESCAPE Randomized Controlled Trial. Stroke. 2016

Outcome measurements in stroke trials commonly use measurements such as the mRS, NIHSS, or Barthel index as surrogates of functional improvement; the primary outcome measurement in the ESCAPE trial was the commonly used 3-month mRS. However, the relationship between outcomes at the functional level versus outcomes at a radiologic or anatomical level are not always delineated. Here, the authors perform a post-hoc analysis of the ESCAPE trial data, to evaluate the effect of IAT on saving brain tissue, and secondarily analyzed (1) clinical and imaging variables at baseline associated with post treatment infarct volume as well (2) the relationship between post treatment infarct volume and the 3-month mRS.

In the ESCAPE trial, the median post treatment infarct volume in the IAT group was significantly
lower than the control group (15.5 mL vs 33.5 mL, p < 0.01). Similarly, regardless of the intervention, successful recanalization in both groups was associated with smaller infarct volumes (14.5 mL vs 35 mL, p < 0.01). Baseline variables that were independently associated with smaller post treatment infarct volume were baseline NIHSS, site of occlusion, baseline ASPECTS and recanalization status, while age, sex, treatment type, IV tPA and time from onset to randomization were not. Post treatment infarct volume was found to strongly predict the 3-month mRS, particularly when including the change from baseline NIHSS.

Some interesting points came out of this study. The results reinforce the finding that recanalization, regardless of intervention, is a significant predictor of smaller infarct volumes. Interestingly, age had no interaction with the infarct volumes; one of the current debates in the stroke world these days is the benefit of IAT in older populations and this finding seems to suggest that age might not be a criteria for intervention if other variables are equal. Thirdly, the association of post treatment infarct volume with 3-month mRS was strongest when modeled with the change in baseline NIHSS, which makes sense, given large strokes in silent areas do not necessarily lead to better (or worse) outcomes, and small strokes in eloquent areas may have small post-treatment infarct volumes, but poor functional outcomes. This last finding, in a roundabout way, reinforces the utility of functional measures, such as mRS or Barthel index as outcome measures for clinical trials, rather than anatomical or radiological markers.