Low Alberta Stroke Program Early CT Score (ASPECTS) Associated with Malignant Middle Cerebral Artery Infarction

Abstract

Background: Early decompressive hemicraniectomy following malignant middle cerebral artery (MCA) infarction reduces mortality and improves clinical outcome. Imaging predictors of malignant infarction may serve as ‘red flags', prompting intensive neurological monitoring and timely intervention. Our objective is to investigate whether lower ASPECTS (Alberta Stroke Program Early CT Score) is associated with malignant MCA infarction. Methods: A retrospective cohort study of all patients with MCA territory ischemic strokes who were admitted to the Royal Melbourne Hospital (RMH) between 1 January 2009 and 31 December 2009 (226 patients included). The main outcome measures were ASPECTS on admission for each patient and the development of malignant MCA infarction. Results: One-hundred-and-eight patients out of 226 (48%) developed malignant MCA infarction. Good (>0.8) inter-rater agreement between observers scoring ASPECTS was observed using weighted kappa, intra-class correlation coefficient and Lin's concordance coefficients. Using receiver operating characteristic (ROC) curve analysis, we validated that ASPECTS 7 was the optimal cut-off score to determine progression to malignant infarction, providing 50% sensitivity and 86% specificity. One hundred and fifty six patients had ASPECTS >7 (69%) and 70 patients had ASPECTS ≤7 (31%). Patients with ASPECTS ≤7 were significantly younger than those with ASPECTS >7, with the median age of each group being 72.5 and 78 respectively (p = 0.02); otherwise the groups were well-matched. With ASPECTS ≤7, 54 out of 70 patients (77%) developed malignant MCA infarction, compared with 54 out of 156 patients (35%) with ASPECTS >7 (age-adjusted OR = 0.12, 95% CI: 0.06, 0.25; p < 0.0001). If ASPECTS ≤7 is a positive result, then the positive predictive value is 77% and the negative predictive value is 65%. The median ASPECTS for developing malignant MCA infarction was 7.5 (IQR: 5 to 10), while the median ASPECTS for not developing MCA infarction was 10 (IQR: 8 to 10), resulting in a significant age-adjusted median difference of 2 (95% CI: 0.8, 3.2; p < 0.0001). We also found that coma on admission is associated with the development of malignant MCA infarction (OR = 22.63, 95% CI: 1.3, 393.7; p = 0.0323) and that a history of hypertension is not associated with the development of malignant MCA infarction (OR = 0.9707, 95% CI: 0.54, 1.75; p = 0.9213). Conclusions: ASPECTS ≤7 on initial brain CT in a patient with MCA infarction is associated with the development of malignant MCA infarction. We recommend close monitoring of, and early consideration of decompressive hemicraniectomy for, acute stroke patients with ASPECTS ≤7.