Abstract 18: Differential Effect of Analyze Early versus Analyze Late prior to Initial Rhythm Analysis in Out-of-Hospital Cardiac Arrest: the Role of EMS Agency
Background: An effective resuscitation strategy in one community may not be effective in another community. We hypothesized that a strategy that prioritized initial Emergency Medical Services (EMS) rhythm analysis (Analyze Early) would provide a survival advantage among EMS systems with lower baseline ventricular fibrillation (VF) survival, while one prioritizing initial EMS CPR (Analyze Late) would provide a survival advantage among systems with higher baseline VF survival.
Methods: We conducted an ancillary study of Analyze Early versus Analyze Late randomized trial of the Resuscitation Outcomes Consortium. Subjects were stratified according to pretrial EMS agency VF survival and their randomization arm. The primary outcome was survival to hospital discharge with favorable functional status. We used a binomial family mixed-effects model to determine whether outcomes from the trial intervention differed according to pretrial EMS agency VF survival.
Results: Characteristics were similar among patients randomized to Analyze Early (n=4964) versus Analyze Late (n=4426). For EMS agencies with pretrial VF survival ≤20%, Analyze Early compared to Analyze Late was associated with a higher likelihood of favorable functional survival (5.5% versus 3.8%, OR=1.50 [1.11,2.0]). Conversely, among agencies with pretrial VF survival > 20%, Analyze Early compared to Analyze Late was associated with lower likelihood of favorable functional survival (6.1% versus 7.5%, OR=0.82 [0.66,1.02]). In the multivariable model, for every 10% improvement in pretrial VF survival, Analyze Late versus Analyze Early was associated with a 34% increase in the odds of favorable functional survival (OR=1.34 [1.07-1.66]).
Conclusion: In this ancillary investigation of a clinical trial evaluating initial EMS CPR strategy, we observed a robust interaction indicating the Analyze Early strategy was associated with greater survival among EMS agencies with lower pretrial VF survival while the Analyze Late strategy was associated with greater survival among EMS agencies with a higher pretrial VF survival. The findings support distinct EMS CPR strategies based on a system’s baseline VF survival in order to achieve optimal outcomes following out-of-hospital cardiac arrest.
- © 2013 by American Heart Association, Inc.