Amplitude Spectrum Area to Guide Defibrillation: A Validation on 1617 Ventricular Fibrillation Patients
Background—The study aimed to validate the ability of amplitude spectrum area (AMSA) to predict defibrillation (DF) success and long-term survival in a large population of out-of-hospital cardiac arrests (CA).
Methods and Results—ECG recorded by automated external defibrillators from different manufactures were obtained from CAs occurring in 8 city-areas. A 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. A 2-sec ECG window before DF was analyzed and AMSA calculated. Univariable, multivariable regression analyses, and area under the receiver operating characteristic (ROC) curve were used for associations between AMSA and study endpoints: DF success, sustained-ROSC, and long-term survival. 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 1.33, 95%CI 1.20-1.37) and sustained-ROSC (OR 1.22, 95%CI 1.17-1.26). Area under the ROC curve for DF success prediction was 0.86 (95%CI 0.85-0.88). AMSA was also significantly associated with long-term survival. The following AMSA thresholds were identified: 15.5 mV-Hz for DF success, and 6.5 mV-Hz for DF failure. In the validation database, AMSA ≥15.5 mV-Hz had a positive predictive value (PV) of 84%, while AMSA ≤6.5 mV-Hz had a negative PV of 98%.
Conclusions—In this large derivation-validation study, AMSA was validated as an accurate predictor of DF success. AMSA appeared also as a predictor of long-term survival.
- Received May 5, 2014.
- Revision received November 11, 2014.
- Accepted November 21, 2014.