Abstract 245: A Validated Score to Predict Poor Neurological Outcome After 72 Hours of Refractory VF/VT in Out of Hospital Cardiac Arrest Patients Requiring Extracorporeal Cardiopulmonary Resuscitation

Introduction: The challenge with neuroprognostication is finding a multimodal prediction model that yields the lowest false positive rate for a poor outcome.

Objectives: To develop and validate a score that accurately predicts poor neurological outcome after 72 hours of ECPR initiation.

Methods: Single-center, retrospective cohort study included 361 OHCA patients who underwent ECPR at the University of Minnesota between December 2015-January 2023. In a 50% random modeling sample, we obtained a derivation (n=180) and validation sample (n=181). The primary outcome was poor neurological outcome (defined as CPC 3-5) at hospital discharge. Neurological predictors were neuro specific enolase (NSE)>3ULN on day 1, myoclonus status epilepticus on day 1-3, neurological pupillary index (NPI)<2 on day 3-6, Glasgow motor=3 on day 3-6, highly malignant pattern on EEG (hmEEG) on day 3-6, CT with anoxic brain injury on day 3, and absent of brainstem reflexes on day 3-6. Univariate and multivariate analysis were performed on each predictor. A simple prediction score tool was constructed and evaluated through ROC analysis. A youden index was used for optimal cut-off.

Results: Of 361 patients, 170 (47%) survived to hospital discharge. Of these, 85% (145/170) survived with favorable neurological outcome. The final multivariate logistic regression model in the derivation sample retained eight predictors: Absence of witnessed status and bystander CPR; downtime≥ 7min, lactate≥ 9mmol, low flow≥ 55min, NSE>3ULN, hmEEG, CT with anoxic brain injury and absence of brainstem reflexes, which were combined to develop an 8-point risk scoring model Minnesota OHCA using ECPR (MECPR). Model discrimination had an AUC of 0.87 [95%CI 0.82-0.92] in the derivation sample and 0.86 [95% CI 0.85-0.92] in the validation sample, and calibration (goodness of fit p=0.04). MECPR≥6 predicted poor neurological outcome with a sensitivity ~21%, specificity 100% and a FPR 0%. A MECPR ≥4 and ≥6 had an 89% and 97% probability of poor neurological outcome, respectively.

Conclusions: A simple, accurate prediction scoring tool (MECPR) based on a multimodal approach after 72hrs of refractory cardiac arrest provides estimates of probability of poor neurological outcome among patients treated with ECPR.