The clinical outcome reflects the heart rhythm profile after defibrillation for shockable rhythm in refractory out-of-hospital cardiac arrest

Abstract Background The prognosis of refractory out-of-hospital cardiac arrest (OHCA) is generally poor. A recent Prague OHCA study has demonstrated that an invasive approach (including extracorporeal cardiopulmonary resuscitation, ECPR) is a feasible treatment strategy in refractory OHCA. Post-hoc analysis of Prague OHCA showed that patients with initial ventricular fibrillation (VF) had manifested better clinical outcomes than those with non-shockable rhythms irrespective of cardiopulmonary resuscitation (CPR) strategy. However, initial shockable rhythm could deteriorate to a non-shockable rhythm during CPR, mainly after defibrillation. The study aimed to stratify the prognosis of patients according to rhythm profile after initial VF in refractory OHCA during pre-hospital and early hospital periods. Methods The analysis enrolled patients with a witnessed OHCA of presumed cardiac cause, with initial VF, and without early recovery of spontaneous circulation. The primary outcome was a composite of survival with Cerebral Performance in Category (CPC) 1 or 2 at 180 days. Results 155 (median age 56y, 10 % females) patients with initial VF were enrolled. The median (IQR) duration of resuscitation was 54 (33-69) minutes. Overall survival with CPC 1 or 2 was 40.4 %. 71 patients were randomized to invasive CPR arm and 84 subjects were treated with conventional CPR. Out of all invasively treated patients, ECPR (veno-arterial extracorporeal membrane oxygenation, VA ECMO) was used in 56 cases without stable recovery of spontaneous circulation and 8 patients primary allocated in conventional group. A proportion of survival with CPC 1 or 2 varied by rhythm course: ongoing VF (9 / 28; 32 %), recovery of organized rhythm (43 / 63; 68 %), documentation of pulseless electrical activity (7 / 30; 23%), and progression to asystole (4 / 34; 12 %); P < 0.05. Tables 1 and 2 show differences in primary endpoint according to rhythm profile between invasive and conventional study arms. Conclusion Deterioration of initial shockable rhythm to asystole bears a poor prognosis in refractory OHCA even when ECPR is readily available. An invasive approach (including VA ECMO) seems to be beneficial in patients with ongoing VF and with regular electrical activity regardless of effective pulsation.