The effect of the localisation of an underlying ST-elevation myocardial infarction on the VF-waveform: A multi-centre cardiac arrest study

The physiology and potential of spectral amplitude area (AMSA) as a guide for resuscitation

Many studies aimed at understanding the electrophysiological mechanisms of ventricular fibrillation (VF) and defibrillation. Although many theories have been proposed about VF, we are still far from fully understanding it. Research has revealed significant insights provided by VF waveform, particularly through its amplitude of spectral area (AMSA). In fact, by potentially representing the energetic status of myocardial cells, AMSA has been shown in both animal and human studies to be a predictor of defibrillation success, return of spontaneous circulation (ROSC), early and long-term survival, and the presence of coronary artery disease underlying the cardiac arrest. The routine use of AMSA in the field could significantly improve resuscitation efforts and lead to a more advanced resuscitation technique by aiding in the selection of the appropriate timing and energy for defibrillation. The aim of this review is to explore what AMSA is and how real-time AMSA use could improve resuscitation directly from the field. If proven to improve patient outcomes, AMSA could significantly transform resuscitation practices, enabling more precise defibrillation strategies and enhanced patient survival.

Amplitude Spectrum Area of ventricular fibrillation to guide defibrillation: a small open-label, pseudo-randomized controlled multicenter trial

BACKGROUND

Ventricular fibrillation (VF) waveform analysis has been proposed as a potential non-invasive guide to optimize timing of defibrillation.

METHODS

The AMplitude Spectrum Area (AMSA) trial is an open-label, multicenter randomized controlled study reporting the first in-human use of AMSA analysis in out-of-hospital cardiac arrest (OHCA). The primary efficacy endpoint was the termination of VF for an AMSA ≥ 15.5 mV-Hz. Adult shockable OHCAs randomly received either an AMSA-guided cardiopulmonary resuscitation (CPR) or a standard-CPR. Randomization and allocation to trial group were carried out centrally. In the AMSA-guided CPR, an initial AMSA ≥ 15.5 mV-Hz prompted for immediate defibrillation, while lower values favored chest compression (CC). After completion of the first 2-min CPR cycle, an AMSA < 6.5 mV-Hz deferred defibrillation in favor of an additional 2-min CPR cycle. AMSA was measured and displayed in real-time during CC pauses for ventilation with a modified defibrillator.

FINDINGS

The trial was early discontinued for low recruitment due to the COVID-19 pandemics. A total of 31 patients were recruited in 3 Italian cities, 19 in AMSA-CPR and 12 in standard-CPR, and included in the data analysis. No difference in primary outcome was observed between the two groups. Termination of VF occurred in 74% of patients in the AMSA-CPR compared to 75% in the standard CPR (OR 0.93 [95% CI 0.18-4.90]). No adverse events were reported.

INTERPRETATION

AMSA was used prospectively in human patients during ongoing CPR. In this small trial, an AMSA-guided defibrillation provided no evidence of an improvement in termination of VF.

TRIAL REGISTRATION

NCT03237910.

FUNDING

European Commission - Horizon 2020; ZOLL Medical Corp., Chelmsford, USA (unrestricted grant); Italian Ministry of Health - Current research IRCCS.