Clinical Impact of the Transient Return of Spontaneous Circulation Before Extracorporeal Cardiopulmonary Resuscitation in Patients with Refractory Out-of-Hospital Cardiac Arrest: A Nationwide Observational Study

Background/Objectives: Out-of-hospital cardiac arrest (OHCA) remains associated with poor survival despite advances in resuscitation. Extracorporeal cardiopulmonary resuscitation (ECPR) is a potential salvage therapy for refractory OHCA, but optimal patient selection remains uncertain. Transient return of spontaneous circulation (ROSC) before ECPR has been proposed as a prognostic marker, although its clinical significance remains unclear. This study aimed to evaluate the impact of transient ROSC before ECPR initiation on survival and neurological outcomes. Methods: We conducted a nationwide retrospective cohort study based on the Korean Out-of-Hospital Cardiac Arrest Surveillance registry (2016–2022). The study population was divided according to the occurrence of transient ROSC prior to ECPR. The primary endpoint was survival to hospital discharge, while favorable neurological outcome served as the secondary endpoint. Propensity score matching (PSM) and multivariable logistic regression analyses were performed. Results: After PSM, survival to hospital discharge (16.7% vs. 17.6%; p = 1.000) and favorable neurological outcomes (10.8% vs. 8.8%; p = 0.814) did not differ between groups. In multivariable analysis, transient ROSC was not associated with survival before (AOR 1.179; 95% CI 0.564–2.464; p = 0.662) or after PSM (AOR 0.592; 95% CI 0.206–1.698; p = 0.329). Similarly, no association was observed for favorable neurological outcomes before (AOR 1.246; 95% CI 0.526–2.951; p = 0.617) or after PSM (AOR 1.094; 95% CI 0.307–3.900; p = 0.890). Conclusions: Transient ROSC before ECPR initiation was not associated with improved survival or neurological outcomes in patients with refractory OHCA.