Early infarct growth predicts long-term clinical outcome in ischemic stroke

Abstract

Background: Ischemic lesions dynamically evolve during the acute phase of stroke. Although the ischemic lesion volume has been considered as a predictor of clinical outcome, it is still controversial whether early changes in ischemic lesion have prognostic information in addition to clinical variables. We hypothesized that early infarct growth on diffusion-weighted imaging (DWI) might be independently associated with long-term outcome in acute ischemic stroke patients.

Methods: This was a prospective study for acute ischemic stroke patients admitted to the Stroke Unit of Asan Medical Center. The patients underwent DWI at baseline (within 24h) and subsequently at 5 days after stroke onset. Early infarct growth was defined as the absolute difference between follow-up and baseline infarct volumes. Poor outcome was a modified Rankin Scale (mRS) at 3 months of 2-6 or 3-6. The association between infarct growth on DWI and clinical outcome was explored using multivariate analysis adjusting for demographics, risk factors for stroke, and other clinical variables. The cut-off values of early infarct growth predicting long-term outcomes were estimated using receiver operating characteristic analysis.

Results: Of 409 patients enrolled, 345 (84.4%) showed any infarct growth (median, 0.63 cm(3); interquartile range [IQR], 0.11-6.33 cm(3); mean ± standard deviation, 9.55 ± 25.54 cm(3)). At the 3-month follow-up, the good outcomes were observed in 217 patients (53.1%) for mRS 0-1 and 303 patients (74.1%) for mRS 0-2. The larger infarct growth was associated with poor clinical outcome (for mRS 2-6, 0.29 cm(3) [IQR 0.04-2.19] vs. 2.16 cm(3) [IQR 0.26-17.68], p<0.001; and for mRS 3-6, 0.39 cm(3) [IQR 0.05-3.25] vs. 7.36 cm(3) [IQR 0.57-26.48], p<0.001). After adjusting age, diabetes, baseline National Institutes of Health Stroke Scale, and baseline infarct volume by multivariate logistic regression analysis, infarct growth was an independent predictor of poor clinical outcomes (for mRS 2-6, odds ratio [OR], 1.03, 95% confidence interval [CI], 1.004-1.06, p=0.03; and for mRS 3-6, OR, 1.03, 95% CI, 1.01-1.05, p=0.01). The cut-off values of infarct growth discriminating between good and poor outcomes were 0.99 cm(3) for mRS 0-1 vs. 2-6 (area under curve, 0.685; P<0.001) and 8.86 cm(3) for mRS 0-2 vs. 3-6 (area under curve, 0.736; P<0.001).

Conclusions: Our present study findings show that infarct growth within a week of onset independently predicts 3-month clinical outcomes. This suggests that short-term changes in infarct volume may serve as a surrogate marker of long-term clinical outcomes after ischemic stroke.

Keywords: Infarct growth; Infarct volume; Ischemic stroke; Outcome.