New Termination-of-Resuscitation Models and Prognostication in Out-of-Hospital Cardiac Arrest Using Electrocardiogram Rhythms Documented in the Field and the Emergency Department

BACKGROUND: Electrocardiogram (ECG) rhythms, particularly shockable rhythms, are crucial for planning cardiac arrest treatment. There are varying opinions regarding treatment guidelines depending on ECG rhythm types and documentation times within pre-hospital settings or after hospital arrivals. We aimed to determine survival and neurologic outcomes based on ECG rhythm types and documentation times. METHODS: This prospective observational study of 64 emergency medical centers was performed using non-traumatic out-of-hospital cardiac arrest registry data between October 2015 and June 2017. From among 4,608 adult participants, 4,219 patients with pre-hospital and hospital ECG rhythm data were enrolled. Patients were divided into 3 groups: those with initial-shockable, converted-shockable, and never-shockable rhythms. Patient characteristics and survival outcomes were compared between groups. Further, termination of resuscitation (TOR) validation was performed for 6 combinations of TOR criteria confirmed in previous studies, including 2 rules developed in the present study. RESULTS: Total survival to discharge after cardiac arrest was 11.7%, and discharge with good neurologic outcomes was 7.9%. Survival to discharge rates and favorable neurologic outcome rates for the initial-shockable group were the highest at 35.3% and 30.2%, respectively. There were no differences in survival to discharge rates and favorable neurologic outcome rates between the converted-shockable (4.2% and 2.0%, respectively) and never-shockable groups (5.7% and 1.9%, respectively). Irrespective of rhythm changes before and after hospital arrival, TOR criteria inclusive of unwitnessed events, no pre-hospital return of spontaneous circulation, and asystole in the emergency department best predicted poor neurologic outcomes (area under the receiver operating characteristic curve of 0.911) with no patients classified as Cerebral Performance Category 1 or 2 (specificity = 1.000). CONCLUSION: Survival outcomes and TOR predictions varied depending on ECG rhythm types and documentation times within pre-hospital filed or emergency department and should, in the future, be considered in treatment algorithms and prognostications of patients with out-of-hospital cardiac arrest. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03222999