Association of Minimal Clinically Important Difference With Infarct Volume in Clinical Poststroke Outcomes

Infarct volume is an imaging biomarker of ischemic tissue injury strongly correlated with poststroke outcomes and reperfusion benefit. We aimed to evaluate the follow-up infarct volume (FIV) difference corresponding to a 1%, 5%, and 10% increase in probability of excellent functional outcomes after intravenous thrombolysis.

Data are from the AcT trial (Alteplase Compared to Tenecteplase in Patients With Acute Ischemic Stroke). Patients with 24-hour infarct volume segmentations were included. The primary outcome was excellent functional outcome (modified Rankin Scale score=0-1). Associations between outcomes and FIV were investigated with regression analyses adjusted for covariates. Sensitivity analyses examined patients with noncontrast computed tomography versus magnetic resonance imaging follow-up and those treated versus not treated with endovascular thrombectomy.

The study included 1478 patients (median age 74 years [interquartile range (IQR), 63-83], 48.2% female). Median FIV was 2.7 mL (IQR, 0-18.2), and 527 (35.7%) achieved excellent functional outcome. FIV was associated with excellent functional outcome: adjusted odds ratio, 0.97 (95% CI, 0.96-0.98) per 1-mL FIV increase. The median ΔFIV corresponding to a 1%, 5%, and 10% increase in adjusted probability of excellent functional outcomes were 1.5 mL (IQR, 1.4-1.9), 7.3 mL (IQR, 6.8-9.3), and 14.6 mL (IQR, 13.6-18.2), respectively. Results were consistent across follow-up imaging modality and endovascular thrombectomy subgroups.

In patients with acute ischemic stroke treated with intravenous thrombolysis, differences of ~1.5 mL, ~7 mL, and ~15 mL in FIV corresponded to a 1%, 5%, and 10% higher absolute probability of achieving excellent functional outcomes. These findings could inform the design of future clinical Phase 2 and proof-of-principle stroke trials that aim to use FIV as a key outcome measure.