[Double sequential electrical transthoracic shocks for refractory atrial fibrillation].

BACKGROUND: Clinical studies have shown that transthoracic cardioversion of atrial fibrillation is dependent on achieving adequate current flow to the heart, which is dependent on transthoracic impedance. When multiple standard cardioversion fails to restore sinus rhythm in patients with atrial fibrillation the double sequential transthoracic shock may be an alternative.

METHODS AND RESULTS: Twenty one consecutive patients with paroxysmal or persistent atrial fibrillation refractory to at least two initial high energy 360 J or 200-300 and 360 J monophasic shocks underwent double sequential shocks with 720 J by means two defibrillators. Mean age was 64 +/- 11 years and mean weight 97 +/- 19 kg (range, 49 to 112). Duration of atrial fibrillation was present < or = 3 months in 76%. Arterial hypertension was present in 38% and lone atrial fibrillation in 33%. Mean left atrial size was 4.5 +/- 0.7 cm (range, 3.5 to 6.0). Sinus rhythm was achieved in 19 (90.4%). Two refractory to biphasic shocks with a median 1,050 J (range, 660 to 1,440 J) without major complications. Multivariate analysis identified duration of atrial fibrillation, > 90 days (RR 0.96, CI 0.95-0.98 p = 0.02) and body weight, 101 +/- 11 kg (RR 0.64, CI 0.46-0.90 p = 0.01) variables independently associated with cardioversion unsuccessful. Patient weight, p = 0.002 was the univariate predictor of unsuccessful cardioversion. High energy cardioversion does not cause cardiac damage evidenced from cardiac troponin T estimation.

CONCLUSION: For refractory atrial fibrillation to conventional cardioversion double sequential transthoracic shocks represents a safe and highly efficacious alternative and may have a general applicability.