Delayed neurological recovery in patients after extracorporeal resuscitation compared to conventional resuscitation. Implications for outcome assessment after cardiac arrest

INTRODUCTION: Extracorporeal cardiopulmonary resuscitation (eCPR) is a rescue therapy for refractory cardiac arrest, with evidence suggesting improved outcomes when performed at experienced centres. Unlike conventional CPR (cCPR), eCPR patients often exhibit delayed recovery. Current guidelines recommend outcome assessment at 1 month or hospital discharge, potentially missing late neurological improvements. This study investigates longitudinal changes in neurological outcomes among eCPR and cCPR patients. METHODS: We conducted a single-centre, retrospective cohort study at the Cardiac Arrest Centre Vienna, including adult patients treated with eCPR or cCPR between January 2020 and May 2024. Patients who survived at least 1 month were analysed. The primary endpoint was the difference in the temporal change in favourable neurological outcome (Cerebral performance category, CPC 1-2) between 1 and 6 months in eCPR versus cCPR patients. Secondary endpoints included CPC distribution, survival rates, and patterns of delayed recovery. RESULTS: Of 912 included patients (209 eCPR, 703 cCPR), 435 were alive at 1 month. In eCPR patients (n = 63), favourable neurological outcome increased from 59 % at 1 month to 87 % at 6 months (p < 0.001), while in cCPR patients (n = 372), it increased from 81 % to 84 % (p = ns). This corresponded to a 29 % versus 3 % increase in patients with a favourable neurological outcome (p < 0.001). There was no change in neurological outcome between 6 and 12 months in either group. Overall, recovery in eCPR patients was prolonged compared to patients after successful resuscitation with cCPR. CONCLUSION: Neurological outcomes in eCPR patients frequently continue to improve after 1 month after cardiac arrest. Future eCPR trials should therefore use outcome assessments beyond 1 month to fully capture recovery potential and patient-centred outcomes.