aMplitude spectral area of ventricular fibrillation and amiOdarone Study in patients with out-of-hospital cArdIaC arrest. The MOSAIC study

Abstract

Objective: Antiarrhythmic drugs are recommended for out of hospital cardiac arrest (OHCA) with shock-refractory ventricular fibrillation (VF). Amplitude Spectral Area (AMSA) of VF is a quantitative waveform measure that describes the amplitude-weighted mean frequency of VF, it correlates with intramyocardial adenosine triphosphate (ATP) concentration, it is a predictor of shock efficacy and an emerging indicator to guide defibrillation and resuscitation efforts. How AMSA might be influenced by amiodarone administration is unknown.

Methods: In this international multicentre observational study, all OHCAs receiving at least one shock were included. AMSA values were calculated by retrospectively analysing the pre-shock ECG interval of 2 s. Multivariable models were run and a propensity score based on the probability of receiving amiodarone was created to compare two randomly matched samples.

Results: 2,077 shocks were included: 1,407 in the amiodarone group and 670 in the non-amiodarone group. AMSA values were lower in the amiodarone group [8.8 (6-12.7) mV·Hz vs. 9.8 (6-14) mV·Hz, p = 0.035]. In two randomly matched propensity score-based groups of 261 shocks, AMSA was lower in the amiodarone group [8.2 (5.8-13.5) mV·Hz vs. 9.6 (5.6-11.6), p = 0.042]. AMSA was a predictor of shock success in both groups but the predictive power was lower in the amiodarone group [Area Under the Curve (AUC) non-amiodarone group 0.812, 95%CI: 0.78-0.841 vs. AUC amiodarone group 0.706, 95%CI: 0.68-0.73; p < 0.001].

Conclusions: Amiodarone administration was independently associated with the probability of recording lower values of AMSA. In patients who have received amiodarone during cardiac arrest the predictive value of AMSA for shock success is significantly lower, but still statistically significant.

Keywords: AMSA; amidoarone; cardiac arrest; defibrillation; ventricular fibrillation.

Figure 1

Bar graph of median values of AMSA with their 95% confidence interval in the amiodarone and in the non-amiodarone groups in the whole population of shocks.

Figure 2

Hodges-Lehmann median difference and 95% confidence showing the reduction of AMSA values from the first two shock to the successive ones both in the non-amiodarone and in the amiodarone group.

Figure 3

Median values of AMSA and their 95% confidential interval in the three tertiles of call to shock time. *indicates statistically significant differences.

Figure 4

AMSA median values and 95% confidence interval in randomly matched, propensity score-based groups of shocks.

Figure 5

Receiver operating characteristic curve of AMSA for the prediction of shock success in amiodarone and non-amiodarone group.