Introduction Despite successful revascularization (TICI 2b or 3), almost half of the acute ischemic stroke patients with large vessel occlusion have a poor outcome. We aim to evaluate the extent by which collateral compensation is independently associated with functional outcome after successful recanalization.

Methods We retrospectively reviewed all acute ischemic stroke (AIS) patients with anterior large vessel occlusion (LVO) who underwent mechanical thrombectomy with successful revascularization in our comprehensive stroke center from 2014 to 2019. Inclusion criteria were age >18, time from last known well to reperfusion <24 hours, and patients who underwent CTP or MRI before and MRI after thrombectomy (within 24 hours). Ischemic core volume in CTP was measured as the relative CBF<30% volume of that normal tissue. MRI ischemic core volumes were calculated manually and by using Automatic Rapid Software (subtraction of 620 ACD volume-CBF<30% in the ischemic hemisphere). Infarct growth rate was defined as: (infarct volume post recanalization – infarct volume before recanalization)/(time from CTP or MRI before recanalization to MRI after recanalization). Functional outcome was measured by the modified Rankin Score (mRS) at 3 months dichotomized as good (mRS≤2) or poor (mRS>2). We used stepwise logistic regression to select variables for the final model. ROC curve analysis was done to identify the best cut-off for infarct growth rate.

Results We identified 123 patients met the inclusion criteria. Patients with poor outcome showed significant higher rates of age >80 (35% vs. 15%, p<0.001), female gender (60% vs. 46%, p=0.024), coronary artery disease (22% vs. 10%, p=0.011), atrial fibrillation (39% vs. 16%, p<0.001), and NIHSS>18 (55% vs. 24%, p<0.001) than patients with good outcome. Furthermore, patients with poor outcome had higher Tmax 10 sec (mean 62.2 sec vs. 44.4 sec, p=0.021) and infarct growth rate (mean 23.6 ml/h vs 8.3 ml/h, p=0.007). Whereas, the two groups were similar for the infarct volume before revascularization (mean 19.3 ml vs. 26.6 ml, p=0.175). Female sex (OR: 2.92, CI: 1.20 – 7.49), presence of atrial fibrillation (OR: 2.84, CI: 1.02 – 8.40), NIHSS>18 (OR: 3.44, CI: 1.35 – 9.21) and a higher infarct growth rate (OR:7.17, CI: 2.12 – 35.2) were independently associated with poor functional outcome at 3 months follow-up. Furthermore, the ROC analysis showed an infarct growth rate of 3 ml/h (AUC: 0.7) with the highest sensitivity (71%) and specificity (52%) for distinguishing between the slow and fast progressors.

Conclusions Failure of hemodynamic compensation measured by infarct growth rate represents an important predictor of poor functional outcome independent of recanalization. Early identification of transfer patients with greater infarct growth rates could help select those patients to alternative triaging systems such as direct to OR to minimize infarct progression.

Disclosures D. Quispe Orozco: None. J. Sequeiros Chirinos: None. C. Zevallos Mau: None. A. Mendez Ruiz: None. S. Abdelkarim: None. S. Ansari: None. A. Mendez Ruiz: None. M. Farooqui: None. S. Dandapat: None. S. Ortega Gutierrez: 2; C; Medtronic, Stryker.