BACKGROUND: It is unclear how invasive resuscitative protocols may impact the time-dependent prognosis of out-of-hospital cardiac arrest (OHCA) resuscitations, or the relationship between intra-arrest transport and outcomes. METHODS: We performed a secondary analysis of the Prague OHCA Study, which randomized refractory OHCAs to "invasive" (intra-arrest transport for possible ECPR initiation) vs. "standard" resuscitation strategies (predominantly performed on-scene). Between groups, we compared outcomes of the initial resuscitation and 180- and 30-day favourable neurological outcomes (CPC 1-2), and within categories based on resuscitation duration (collapse-to-ROSC/ECPR interval). We plotted the dynamic probability of favourable outcomes with increasing durations of unsuccessful resuscitation. RESULTS: Among invasive and standard groups, respectively: 34/124 (27%) vs. 58/132 (44%) had sustained ROSC (difference -17%, 95%CI -5.0, -28); 38/124 (31%) vs. 24/132 (18%) had 30-day favourable neurological outcomes (difference 12%; 95%CI 2.0, 23); and 39/124 (31%) vs. 29/132 (22%) had 180-day favourable neurological outcomes (difference 9.5%; 95%CI -1.3, 20). For favourable outcome cases: standard group resuscitation durations were right-skewed within the first 60 min; for the invasive group the distribution was bimodal, extending to 77 min. For invasive- and standard-treated cases, the probability of favourable outcomes among those in refractory arrest at 30 min was 28% and 7.6%, respectively; declining to 0% at 77 and 60 min. CONCLUSION: In comparison to standard resuscitation, invasive strategy cases had fewer achieve sustained ROSC, however improved overall 30-day favourable neurological outcomes. While standard resuscitation yield was limited to < 60 min, invasive protocols offer a second extended window of potential successful resuscitation.

2nd Department of Medicine Department of Cardiovascular Medicine 1st Faculty of Medicine Charles University Prague and General University Hospital Prague Czech Republic

2nd Department of Medicine Department of Cardiovascular Medicine 1st Faculty of Medicine Charles University Prague and General University Hospital Prague Czech Republic; Emergency Medical Service Prague Czech Republic

2nd Department of Medicine Department of Cardiovascular Medicine 1st Faculty of Medicine Charles University Prague and General University Hospital Prague Czech Republic; Institute for Heart Diseases Wroclaw Medical University Wrocław Poland

Czech Institute of Informatics Robotics and Cybernetics Czech Technical University Prague Czech Republic

Departments of Emergency Medicine St Paul's Hospital and the University of British Columbia Vancouver Canada

References provided by Crossref.org

Cardiac Rhythm Conversions and the Outcome in Refractory Out-of-Hospital Cardiac Arrest: Extracorporeal Versus Conventional Resuscitation