Abstract / Summary
Background: Out-of-hospital cardiac arrest (OHCA) with pulseless electrical activity (PEA) has a poor prognosis and is aetiologically heterogeneous. We aimed to identify prehospital predictors of a favourable outcome, overall and by presumed aetiology. Methods: This nationwide cohort study analysed 442,630 adults with OHCA and an initial rhythm of PEA from the All-Japan Utstein Registry between 2005 and 2024. The primary outcome was a favourable neurological outcome at 1 month. Two models were fitted, at the scene and at hospital arrival, each also within each aetiology. Epinephrine and advanced airway management (AAM) were assessed by time-dependent propensity score sequential matching. Results: At the scene, a witnessed arrest (risk ratio [RR], 1.65) predicted a favourable neurological outcome, and a longer response time predicted a worse one (RR, 0.66; 10 versus 5 min). The gradient with age was steeper in cardiac than non-cardiac PEA (RR, 0.38 versus 0.78). At hospital arrival, prehospital return of spontaneous circulation (RR, 23.31) was the strongest predictor, but conversion to a shockable rhythm predicted a favourable outcome only in cardiac PEA and a worse outcome in non-cardiac PEA (RR, 1.37 versus 0.73). Standardised to a common covariate distribution, 1-month survival was higher in non-cardiac PEA, whereas a favourable neurological outcome was more likely in cardiac PEA. After time-dependent adjustment, the apparent harm from epinephrine and AAM was attenuated. Conclusions: Prehospital information available before hospital arrival predicted a favourable neurological outcome, but its prognostic meaning depended on the presumed aetiology. These independent prehospital predictors could inform future risk stratification.