Abstract 146: Association Between Quantitative Waveform Measures of the Ventricular Fibrillation Electrocardiogram and Defibrillation Success in the ROC ALPS Trial

Abstract

Introduction: During out-of-hospital cardiac arrest (OHCA), features of the ventricular fibrillation electrocardiogram (ECG) have been correlated with outcomes. Understanding factors affecting the variability of these features may elucidate their utility. We examined the association between quantitative waveform measures (QWM) of the VF ECG and defibrillation success in the context of the Resuscitation Outcomes Consortium (ROC) amiodarone, lidocaine and placebo (ALPS) trial. Methods: We retrospectively obtained case data for patients enrolled in the ALPS trial from the ROC data coordinating center (DCC). The primary trial enrolled emergency medical services (EMS) – treated OHCA patients with at least one failed defibrillation from 2012 to 2015 at 10 sites across the ROC network for randomization to amiodarone, lidocaine or placebo. We included all enrolled cases with an ECG file available through the DCC. ECG signals were analyzed with custom, semi-automatic software to identify shocks, parse pre-shock ECG segments, and identify pre- and post- defibrillation rhythms, including post-shock return of organized rhythm (ROOR). Three QWM – AMSA, centroid frequency (CF), and median slope (MS) – were calculated for pre-shock ECG segments. Multivariable logistic regression models accounting for repeated shocks were constructed with outcome ROOR, adjusting for ALPS treatment arm, shock number and relevant case characteristics. Results: A total of 1242 cases were available for analysis, comprising a total of 5,408 defibrillation events with identifiable pre-shock VF. Mean (SD) QWM values for all shocks were: AMSA{6.74 (10.80)}, CF{3.98 (1.68)} , MS{0.02 (0.02)}. CF, but not AMSA or MS, differed significantly between ALPS treatment arms when controlling for shock number (p amio < 0.001; p lido = 0.016). All QWM were significantly directly associated with defibrillation success in multivariable models (OR AMSA =1.03 [95%CI: 1.02 – 1.04]; OR CF =1.35 [95%CI: 1.26 – 1.45]); OR MS =1.05 [95%CI: 1.04 – 1.06]). Conclusions: In the ROC ALPS trial, QWM were associated with defibrillation success independent of shock number or treatment arm.