Abstract P520: Infarct Growth Rate is an Independent Predictor of Poor Outcome and Mortality After Mechanical Thrombectomy With Successful Reperfusion

Abstract

Introduction: Despite treatment with mechanical thrombectomy (MT), some patients fail to regain functional independence at 90 days. The growth of the ischemic core varies across patients, and likely reflects differences in collateral flow and ischemic tolerance. In this study, we sought establish the optimal infarct growth rate (IGR) threshold to differentiate between slow and fast progressors and assess its ability to predict poor outcome. Methods: We retrospectively identified patients with anterior large-vessel occlusion (LVO) stroke with successful MT (mTICI ≥ 2b) at two comprehensive stroke centers. Final infarct volume (FIV) was calculated from post-MT Diffusion-weighted MRI. Assuming relative stability of the FIV after successful reperfusion, we defined IGR as [FIV (ml)] / [Time from stroke onset to reperfusion (hours)]. Good clinical outcome was defined as a modified Rankin scale score (mRS) ≤2. We used Receiver Operating Characteristics (ROC) analysis to calculate the optimal IGR threshold with high specificity for predicting a poor outcome. Multivariate logistic regression analysis was performed to evaluate the association of fast progressors (IGR ≥ 7.14 ml/h) on the poor functional outcome and mortality. Results: Of the 212 patients (age 68 ± 15, 51% female, NIHSS 15 ± 7) included, 110 (51.8%) patients had a poor outcome. The median IGR was significantly higher in patients with poor compared to good outcome (7 ml/h vs. 3.1 ml/h, p<0.001). An IGR ≥ 7.14 ml/h showed a sensitivity of 0.49 and a specificity of 0.7 to predict a poor outcome with an area under the ROC curve of 0.65 (95% CI, 0.58-0.73). IGR ≥ 7.14 ml/h was an independent predictor of poor outcome (OR 2.2, 95% CI 1.1-4.6, p=0.036) and mortality (OR 4.2, 95% CI 1.8-10.6, p=0.001) after adjusting for age, sex, atrial fibrillation, NIHSS and ASPECTS. Ordinal regression showed that the odds of having better outcomes decrease 60% in fast progressors (OR 0.40, 95% CI: 0.22-0.70, p=0.001) after adjusting for age, sex, atrial fibrillation, NIHSS, and ASPECTS. Conclusions: IGR is an independent predictor of poor outcome and mortality in patients with successful MT. Early identification of this population might help to institute therapeutic strategies of accelerating reperfusion and slowing the IGR.