AbstractObjectiveExtracorporeal cardiopulmonary resuscitation (ECPR), while resource-intensive, may improve outcomes in selected patients with refractory out-of-hospital cardiac arrest (OHCA). We sought to identify patients who fulfilled a set of ECPR criteria in order to estimate: (1) the proportion of patients with refractory cardiac arrest who may have benefited from ECPR; and (2) the outcomes achieved with conventional resuscitation.MethodsWe performed a secondary analysis from a 52-month prospective registry of consecutive adult non-traumatic OHCA cases from a single urban Canadian health region serving one million patients. We developed a hypothetical ECPR-eligible cohort including adult patients <60 years of age with a witnessed OHCA, and either bystander CPR or EMS arrival within five minutes. The primary outcome was the proportion of ECPR-eligible patients who had refractory cardiac arrest, defined as termination of resuscitation pre-hospital or in the ED. The secondary outcome was the proportion of EPCR-eligible patients who survived to hospital discharge.ResultsOf 1,644 EMS-treated OHCA, 168 (10.2%) fulfilled our ECPR criteria. Overall, 54/1644 (3.3%; 95% CI 2.4%-4.1%) who were ECPR-eligible had refractory cardiac arrest. Of ECPR-eligible patients, 114/168 (68%, 95% CI 61%-75%) survived to hospital admission, and 70/168 (42%; 95% CI 34-49%) survived to hospital discharge.ConclusionIn our region, approximately 10% of EMS-treated cases of OHCA fulfilled our ECPR criteria, and approximately one-third of these (an average of 12 patients per year) were refractory to conventional resuscitation. The integration of an ECPR program into an existing high-performing system of care may have a small but clinically important effect on patient outcomes.