Extracorporeal cardiopulmonary resuscitation (ECPR) is a resource-intensive treatment for refractory out-of-hospital cardiac arrest (OHCA), underscoring the importance of identifying patients with favorable neurological outcomes. We investigated whether waveform changes from initial shockable cardiac rhythm to alternative cardiac rhythm upon hospital arrival can predict the outcomes of patients undergoing ECPR for OHCA.

This secondary analysis of the SAVE-J II study included patients with OHCA who received ECPR at 36 emergency departments in Japan. We identified patients who experienced OHCA with shockable cardiac rhythm at the scene and subsequently underwent ECPR. We performed multivariable logistic regression analysis to assess the association between the waveform at hospital arrival and outcomes. The primary outcome was a favorable neurological outcome (cerebral performance category 1 or 2) at 1 month after arrest.

Overall, 1114 patients were eligible for analysis. The rate of achieving a favorable neurological outcome was highest in patients who had sustained shockable cardiac rhythm on hospital arrival, followed by those with pulseless electrical activity and asystole (22.4 % vs. 9.5 % vs. 2.7 %, P   <  0.001). The difference remained significant after adjusting for confounding factors, with adjusted odds ratio (95 % CI) of 0.35 (0.21–0.58) and 0.08 (0.03–0.20) for pulseless electrical activity and asystole groups, respectively.

The waveform transition from shockable to alternate cardiac rhythm was associated with significantly poor outcomes after ECPR for OHCA. Patients with waveform conversion from VF/VT to asystole upon hospital arrival had exceedingly low probabilities of achieving favorable neurological outcomes, necessitating careful consideration of ECPR's appropriateness in this population.