Abstract 311: Amplitude Spectrum Area to Guide Defibrillation: A Conclusive Validation in 1,617 Ventricular Fibrillation Patients

Background: In a highly populated Region of northern Italy, Lombardia, we validated the capability of amplitude spectrum area (AMSA) to predict defibrillation (DF) success in of out-of-hospital cardiac arrests (CA) due to ventricular fibrillation. We hypothesized that AMSA would be an accurate predictor of DF success so that threshold values of AMSA might be used to guide CPR intervention, i.e. chest compression or DF. Methods: ECG data recorded by automated external defibrillators from different manufactures were obtained from CAs occurring in 8 city-areas in Lombardia. A first database, including 2.447 DFs from 1.050 patients, was used as derivation group, while an additional database, including 1.381 DFs from 567 patients, served as validation group. A 2 sec ECG window ending 0.5 sec before DF was analyzed and AMSA was calculated. Univariate and multivariate regression analyses and area under the receiver operating characteristic (ROC) curve were used to determine associations between AMSA and study endpoints, i.e. DF success, sustained ROSC, and long-term survival. Results: Among the 2.447 DFs of the derivation database, 26.2% were successful. AMSA was significantly higher prior to a successful DF than a failing one (13±5 vs. 6.8±3.5 mV-Hz) and was an independent predictor of DF success (OR 1.40, 95%CI 1.36-1.44) and sustained ROSC (OR 1.21, 95%CI 1.16-1.25). Area under the ROC curve for DF success prediction was 0.86 (95%CI 0.85-0.88, p 15.5 mV-Hz for DF success and 15.5 predicted DF success with a positive predictive value of 84%, while AMSA Conclusions: In this large derivation-validation study, AMSA was proved to be an accurate predictor of DF success. AMSA appeared also as a predictor of short- and long-term survival after cardiac arrest.