Short ECG Segments Predict Defibrillation Outcome using Quantitative Waveform Measures

Abstract Aim Quantitative waveform measures of the ventricular fibrillation (VF) electrocardiogram (ECG) predict defibrillation outcome. Calculation requires an ECG epoch without chest compression artifact. However, pauses in CPR can adversely affect survival. Thus the potential use of waveform measures is limited by the need to pause CPR. We sought to characterize the relationship between the length of the CPR-free epoch and the ability to predict outcome. Methods We conducted a retrospective investigation using the CPR-free ECG prior to first shock among out-of-hospital VF cardiac arrest patients in a large metropolitan region (n = 442). Amplitude Spectrum Area (AMSA) and Median Slope (MS) were calculated using ECG epochs ranging from 5 seconds to 0.2 seconds. The relative ability of the measures to predict return of organized rhythm (ROR) and neurologically-intact survival was evaluated at different epoch lengths by calculating the area under the receiver operating characteristic curve (AUC) using the 5-second epoch as the referent group. Results Compared to the 5-second epoch, AMSA performance declined significantly only after reducing epoch length to 0.2 seconds for ROR (AUC 0.77 to 0.74, p = 0.03) and with epochs of ≤ 0.6 seconds for neurologically-intact survival (AUC 0.72 to 0.70, p = 0.04). MS performance declined significantly with epochs of ≤ 0.8 seconds for ROR (AUC 0.78 to 0.77, p = 0.04) and with epochs ≤ 1.6 seconds for neurologically-intact survival (AUC 0.72 to 0.71, p = 0.04). Conclusion Waveform measures predict defibrillation outcome using very brief ECG epochs, a quality that may enable their use in current resuscitation algorithms designed to limit CPR interruption.