Abstract WMP91: The Penumbra Salvage Index (PSI) As A Novel Measure Of Successful Reperfusion

Objective: We propose a novel measure, the PSI, to evaluate procedural success and prognostication after EVT and compare its prognostic ability with successful reperfusion (mTICI ≥2b). Methods: SELECT EVT patients with adequate follow-up MR DWI imaging were stratified based on PSI [ratio of salvaged tissue volume (Tmax >6s volume at baseline – f/up DWI infarct volume) to the Tmax >6s volume at baseline] into good (PSI≥50%) and poor penumbral salvage (PSI<50%). Multivariable regression models examined the association of PSI with functional outcomes as well as predictors of PSI. ROC curve analysis evaluated the predictive ability of PSI and compared it with mTICI≥2b. Results: 142/206(69%) had good penumbral salvage, with better CT ASPECTS (Good PSI: 9(7-10) vs Poor PSI: 7(6-9),p<0.001), baseline core infarct (Good PSI: 5.9(0.0-20.0)ml vs Poor PSI: 19.4(3.4-46.3)ml, p<0.001) and mTICI≥2b (Good PSI:91% vs Poor PSI: 64%, p<0.001). Good PSI was independently associated with higher odds of mRS 0-2 (Good PSI: 69% vs Poor PSI: 26%, aOR:5.89, 95%CI:2.25-15.45, p<0.001) and mRS 0-1 (Good PSI: 56% vs Poor PSI: 16%, aOR: 4.98, 95%CI:1.86-13.31, p=0.001). Predictors of a good PSI included a lower presenting NIHSS (aOR: 0.93, 95%CI: 0.87-0.99, p=0.026), smaller ischemic core (aOR: 0.96, 95%CI: 0.95-0.98, p<0.001) larger Tmax>6s volume (aOR: 1.01, 95%CI: 1.00-1.02, p=0.003) and mTICI≥2b (aOR: 8.84, 95%CI: 3.16-24.71, p<0.001). PSI demonstrated better AUC values (0.811) as compared to mTICI≥2b (0.786) in the ROC analysis. Conclusion: Good penumbral salvage is associated with higher odds of functional independence, and has a better predictive value than successful reperfusion on cerebral angiogram after EVT. Prospective studies are needed to confirm the predictive utility of the PSI.