Biphasic transoesophageal vs. transthoracic electrical cardioversion of persistent atrial fibrillation

Abstract

Objective: To compare the efficacy and safety of transoesophageal (TOC) vs. transthoracic (TTC) electrical cardioversion, both with biphasic shocks, for sinus rhythm (SR) restoration in patients with persistent atrial fibrillation (AF).

Methods: We randomised 210 patients (151 male, 59 female, mean age 66 +/- 9 years) with persistent AF into two groups: group 1 (n = 104) undergoing TOC with a step-up protocol of 30, 50, 70 and 100 J, and group 2 (n = 106) undergoing TTC with a step-up protocol of 70, 100, 120 and 150 J.

Results: The two groups were homogeneous as for clinical and instrumental characteristics, except for left ventricular ejection fraction (50.5 +/- 10% in group 1 vs. 53 +/- 8% in group 2, P < 0.05) and thoracic impedance (63 +/- 8 Omega in group 1 vs. 66 +/- 6 Omega in group 2, P < 0.005). SR was restored in 98 (94%) group 1 patients vs. 99 (93%) group 2 patients (P = NS). First shock was effective in 48 (46%) group 1 patients vs. 54 (51%) group 2 patients (P = NS). Mean delivered energy was 50.4 +/- 23.6 and 95.1 +/- 29.6 J; mean effective energy was 47.3 +/- 20.7 and 91.2 +/- 26.6 J in group 1 and group 2, respectively. Cross-over to the highest energy level was never effective. TOC tolerability was optimal (mean discomfort score 1.2 on a 1-4 grading scale). Markers of myocardial necrosis did not increase and no procedure-related complications occurred. On logistic regression analysis, the most predictive variables of unsuccessful cardioversion were AF duration (P = 0.0001) and low left atrial appendage emptying velocity (P = 0.02).

Conclusions: Both TOC and TTC with biphasic shocks are effective and safe for SR restoration in patients with persistent AF; however, the considerably lower levels of delivered and effective energies for SR restoration allow TOC to be performed during mild sedation with optimal tolerability, thus avoiding general anaesthesia.