CT perfusion core and ASPECT score prediction of outcomes in DEFUSE 3

Background: The role of Alberta Stroke Program Early CT Score (ASPECTS) for thrombectomy patient selection and prognostication in late time windows is unknown.

Aims: We compared baseline ASPECTS and core infarction determined by CT perfusion (CTP) as predictors of clinical outcome in the Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke 3 (DEFUSE) 3 trial.

Methods: We included all DEFUSE 3 patients with baseline non-contrast CT and CTP imaging. ASPECTS and core infarction were determined by the DEFUSE 3 core laboratory. Primary outcome was functional independence (modified Rankin Scale (mRS) ≤2). Secondary outcomes included ordinal mRS shift at 90 days and final core infarction volume.

Results: Of the 142 patients, 85 patients (60%) had ASPECTS 8-10 and 57 (40%) had ASPECTS 5-7. Thirty-one patients (36%) with ASPECTS 8-10 and 11 patients (19%) with ASPECTS 5-7 were functionally independent at 90 days (p = 0.03). In the primary and secondary logistic regression analysis, there was no difference in ordinal mRS shift (p = 0.98) or functional independence (mRS ≤ 2; p = 0.36) at 90 days between ASPECTS 8-10 and ASPECTS 5-7 patients. Similarly, primary and secondary logistic regression analyses found no difference in ordinal mRS shift (p = 1.0) or functional independence (mRS ≤ 2; p = 0.87) at 90 days between patients with baseline small core ( < 50 ml) versus medium core (50-70 ml).

Conclusions: Higher ASPECTS (8-10) correlated with functional independence at 90 days in the DEFUSE trial. ASPECTS and core infarction volume did not modify the thrombectomy treatment effect, which indicates that patients with a target mismatch profile on perfusion imaging should undergo thrombectomy regardless of ASPECTS or core infarction volume in late time windows.