Background: The impact of baseline ischemia on Aspects and evolution over 24 hours may be distinct in the late thrombectomy time window recently established by dawn. Aspects may enable practical triage of thrombectomy candidates more than 6 hours after onset.
Methods: The dawn Imaging Core Lab independently scored Aspects at baseline and 24 hours. Descriptive statistics characterized Aspects on CT or MRI at baseline and 24 hours, delineating serial ASPECTS change or infarct evolution over 24 hours and analyzing associations with clinical variables, treatment arm and clinical outcomes.
Results: 193 DAWN subjects (mean age 70.2 ± 13.7 yrs; 56% female; baseline NIHSS median 17 (14, 21) had core lab adjudicated Aspects at both baseline and 24 hours. Baseline Aspects was median 8.0 (3-10), with 89/193 (46.1%) between 0-7 and 104/193 (53.9%) between 8-10. 24-hour ASPECTS was median 6.0 (0-9), with serial ASPECTS change or infarct evolution of median -1, ranging from -8 to 0. Multivariate logistic regression showed age (OR 1.03 (yr) 95%CI (1.01-1.05), p=0.011) and male sex (OR 0.51 95%CI (0.30-0.86), p=0.012) predicted higher baseline ASPECTS. Higher 24-hour ASPECTS was predicted by endovascular treatment (OR 2.42 95%CI (1.42-4.12), p=0.001), baseline glucose < 150 mg/dL (OR 2.23 95%CI (1.19-4.18), p=0.012), lower baseline NIHSS (OR 0.92 95%CI (0.88-0.97), p=0.003) and age (OR 1.03 (yr) 95%CI (1.01-1.05), p=0.002). Good clinical outcome (day 90 mRS 0-2) was predicted by 24-hour ASPECTS (OR 1.50 95%CI (1.22-1.85), p<0.001). Dramatic infarct evolution (ASPECTS decrease ≥ 6) occurred in 15/193 (7.8%). Elevated baseline serum glucose (mg/dL) was a potent predictor of serial ASPECTS change of 4, 5, or 6 points (OR 1.01, all p<0.010). Serial ASPECTS change was dramatically influenced by treatment arm (p=0.004), including 0 ASPECTS change in 40/99 (40.4%) of the endovascular arm and only 18/94 (19.1%) of the medical arm.
Conclusions: DAWN subjects enrolled with small infarct cores in the late time window had a broad range of baseline ASPECTS. 24-hour ASPECTS, strikingly influenced by endovascular therapy, predicted good clinical outcomes. Infarct evolution on serial ASPECTS provides robust biomarker data for endovascular therapy up to 24 hours from onset.