Anaesthesia for cardioversion: a prospective randomised comparison of propofol and etomidate combined with fentanyl

External electrical cardioversion is mostly performed solely under sedatives or hypnotics, although the procedure is painful. The aim of this prospective randomised study was to compare two anaesthetic protocols that included analgesia.

Patients with persistent atrial fibrillation were randomised to receive intravenously either fentanyl 50 μg and propofol 0.5 mg/kg (group P) or fentanyl 50 μg and etomidate 0.1 mg/kg (group E), while breathing spontaneously 100% oxygen. In the case of inadequate anaesthesia, repeated doses of 20 mg propofol (group P) or 4 mg etomidate (group E) were given as often as necessary until loss of eyelid reflex. Cardioversion was achieved with an extracardiac biphasic electrical shock ranging from 200 to 300 J, performed three times at most.

Forty-six patients (25 in group P, 21 in group E), aged 64 ± 9 years, were enrolled in the study. There were no differences between the study groups concerning left ventricular ejection fraction, the dimension of the left atrium, the number of shocks needed or the number of unsuccessful cardioversions. Patients in group E had a shorter time from injection of the induction agents until loss of consciousness (49 vs. 118 s, p=0.003) and until the first shock was given (61 vs. 135 s, p=0.004). Systolic blood pressure decreased significantly (repeated measurements ANOVA with Bonferroni adjustment) in group P when the baseline value was compared to that after anaesthesia induction (mean decrease 15.2 mmHg, 95% CI 5.6-24.8 mmHg, p=0.001) and to the value after recovery (mean decrease 15.2 mmHg, 95% CI 4.8-25.7 mmHg, p=0.002). Manual ventilation was required in 7 and 9 patients in groups P and E, respectively (p=0.360).

Both anaesthetic regimens provided excellent conditions for external electric cardioversion. In addition, etomidate in combination with fentanyl had a shorter induction time and ensured haemodynamic stability.