Background and Purpose The main premise of reperfusion therapy in acute ischemic stroke (AIS) is to prevent the conversion of the salvable penumbra into irreversible infarct core thereby reducing the final stoke size. Indeed, previous studies have demonstrated a strong correlation between final infarct volumes and functional outcomes. We sought to establish the optimal final infarct thresholds that best correlate with independent functional outcomes.
Methods Multicenter retrospective analysis across five large academic centers. Consecutive patients meeting the following criteria were included: (1) anterior circulation stroke; (2) available final stroke imaging volumetric analysis; (3) available modified Rankin scale (mRS) score at 90 days. Receiver operating characteristic (ROC) curves were created to help defining the optimal final stroke volume points that discriminate a 90-day mRS ≤2.
Results A total of 484 consecutive patients were identified. The mean age was 65.6±14.6 years. The mean baseline NIHSS was 14.2±7.1. The mean final stroke volume was 77.7±88.5 cc (median, 40.5 cc). A total of 201 out of the 484 (41.5%) of the patients achieved functional independence at 90 days. The ROC analysis demonstrated that final infarct volume (FIV) was a strong discriminator of independent outcomes with an area under the curve [AUC] of 0.778. The best cut-off point for discriminating 90-day mRS ≤2 was 35 cc of FIV (70% specificity; 70% sensitivity). The AUC could be improved by excluding older patients. In patient <65 years, the AUC was 0.844 with an optimal discriminating point at 53 cc (75% specificity; 75% sensitivity). The exclusion of patients >80 years yielded an AUC of 0.797 with an optimal FIV discriminating point at 40 cc (72% specificity; 72% sensitivity). In this population, FIV of 29 cc had 80% specificity and 62% sensitivity whereas FIV of 15 cc had 90% specificity but only 40% sensitivity for an independent functional outcome.
Conclusions Final infarct volume is a strong surrogate for good outcomes after AIS. Our data suggest that the exclusion of patients with infarct volumes >35–40 cc on baseline imaging may enhance the chances of a positive confirmatory clinical trial of reperfusion in AIS.