Real Time Amplitude Spectrum Area to Guide Defibrillation

In the AMSA-CPR intervention, upon arrival of the advanced life support (ALS) rescue team at the cardiac arrest scene and application of the defibrillatory pads to the patient's chest and power on of the defibrillator with the real time AMSA analysis:

* If AMSA is ≥ 15.5 mV-Hz, an immediate defibrillation is attempted, followed by CPR
* If AMSA is < 15.5 mV-Hz, defibrillation is not attempted and CPR is delivered
* During the 2-min cycle of CPR, AMSA is measured during pauses for ventilations (every 30 CC, approximately every 20/25 sec). If an AMSA value ≥ 15.5 mV-Hz is achieved prior to cycle completion, an immediate defibrillation is delivered (thus the defibrillation attempt is anticipated)

After completion of the first 2-min CPR cycle:

* If AMSA is ≤ 6.5 mV-Hz, the defibrillation is not attempted but CPR is continued
* If AMSA is > 6.5 mV-Hz, an immediate defibrillation attempt is delivered, followed by CPR
* During the 2-min cycle of CPR, AMSA is measured during pauses for ventilations (every 30 CC, approximately every 20/25 sec). If an AMSA value ≥ 15.5 mV-Hz is achieved prior to cycle completion, an immediate defibrillation is delivered

After completion of the second 2-min CPR cycle and till the end of the resuscitative intervention:

• CPR is continued based on standard 2015 ERC guidelines (a defibrillation attempt every 2-min CPR cycles), except for the possibility to anticipate the defibrillation attempt if AMSA becomes ≥ 15.5 mV-Hz during the CPR cycle.

In the standard CPR intervention, upon arrival of the ALS team at the cardiac arrest scene, and application of the defibrillatory pads to the patient's chest and power on of the defibrillator:

• a defibrillation is immediately attempted and CPR is then started and continued for 2- min. Analysis of rhythm and subsequent defibrillation attempts are performed every 2-min CPR cycles.

In both study groups, the quality of CC and ventilation is monitored in real time thought the feedback integrated into the defibrillator.

• AMSA (Diagnostic test), also known as VF waveform analysis: A non-invasive and real time VF (Amplitude Spectrum Area) AMSA analysis is performed during chest compression pauses for delivery of 2 ventilations, from the ECG acquired from the conventional defibrillatory pads
• Defibrillation (Procedure), also known as electric countershock: delivery of the defibrillation is attempted to terminate VF either based on AMSA value (in the AMSA-CPR arm) or every 2-min CPR cycle as recommended by current guidelines (in the Standard-CPR arm)
• CPR (Procedure), also known as resuscitation maneuvres: chest compressions and ventilations at a rate of 30:2

Primary outcomes

• Return of spontaneous circulation (ROSC) [At day 0: from date of initiation of the cardiopulmonary resuscitation (CPR) maneuvres up to ROSC or up to 1 hour of CPR (which comes first)]: Termination of ventricular fibrillation with achievement of ROSC for an AMSA value ≥ 15.5 mV-Hz

Secondary outcomes

• Defibrillation attempts [At day 0: from date of initiation of the cardiopulmonary resuscitation (CPR) maneuvres up to ROSC or up to 1 hour of CPR (which comes first)]: Number of defibrillations to achieve ROSC
• CPR duration [At day 0: from date of initiation of the cardiopulmonary resuscitation (CPR) maneuvres up to ROSC or up to 1 hour of CPR (which comes first)]: duration of CPR in minutes prior to achieve ROSC
• Cardiac troponins [at 6 and 24 hours after ICU admission]: assessment of circulating levels of high sensitive cardiac troponin T in plasma as marker of cardiac injury
• Short term survival [at hospital admission and 24 hours after ROSC]: number of patients alive after initial resuscitation
• Long term survival [at 1 and 6 months after ROSC]: number of patients alive after initial resuscitation

Sex: All, ages: 18 Years to any

Inclusion Criteria:

All adult patients (age ≥ 18) suffering of out-of-hospital non traumatic cardiac arrest of presumably cardiac etiology with a presenting shockable rhythm requiring electrical defibrillation: Ventricular Fibrillation and pulseless Ventricular Tachycardia.

Exclusion Criteria:

* age < 18 years old
* pregnancy
* cardiac arrest with a non-shockable rhythm (pulseless electrical activity and asystole)
* a defibrillation delivered by an AED prior to ALS arrival
* cardiac arrest of traumatic origin
* non-cardiac cause of cardiac arrest
* presumable irreversible death or known terminal illness at the beginning of ALS
* clinical death
* participation in another clinical or device trial within the previous 30 days
* refused informed consent to the use of data.

• Results publication: Ruggeri L, Fumagalli F, Bernasconi F, Semeraro F, Meessen JMTA, Blanda A, Migliari M, Magliocca A, Gordini G, Fumagalli R, Sechi G, Pesenti A, Skrifvars MB, Li Y, Latini R, Wik L, Ristagno G. Amplitude Spectrum Area of ventricular fibrillation to guide defibrillation: a small open-label, pseudo-randomized controlled multicenter trial. EBioMedicine. 2023 Apr;90:104544. doi: 10.1016/j.ebiom.2023.104544. Epub 2023 Mar 26. PMID 36977371

• Giuseppe Ristagno, MD, PhD, Study chair, Istituto Di Ricerche Farmacologiche Mario Negri
• Roberto Latini, MD, Study chair, Istituto Di Ricerche Farmacologiche Mario Negri