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Long B, Gottlieb M. Anterior‐posterior versus anterior‐lateral pad positioning for electrical cardioversion of atrial fibrillation. Academic Emergency Medicine. Published online January 13, 2023:acem.14662.

Study Population: 10 trials with 1,677 patients with atrial fibrillation undergoing electrical cardioversion

Efficacy Endpoints

Rate of successful cardioversion, success at low energy

Harm Endpoints

Not reported

Narrative

Atrial fibrillation (AF) is a common arrhythmia evaluated and managed in the emergency department (ED), and treatment may include electrical cardioversion.1^, 2^, 3 Success of electrical cardioversion depends on several factors including AF duration and, possibly, pad positioning.4^, 5 The most common pad positions are the anterior-posterior (AP) and anterior-lateral (AL), and several randomized controlled trials (RCTs) have compared the two.4^, 5^, 6^, 7^, 8

The systematic review summarized here included RCTs comparing AP and AL pad positioning during elective electrical AF cardioversion.9 To be included, RCTs had to report cardioversion success rate, which was the primary outcome. Other outcomes included cardioversion success at low energy (≤200 J monophasic or ≤120 J biphasic), total number of shocks, mean transthoracic impedance, and mean shock energy.

The meta-analysis identified 10 RCTs with 1,677 subjects (831 AP, 846 AL).9 Two trials were multicenter.4^, 8 AP positioning involved placement at the right sternal border and left infrascapular region, except for one trial that used the left parasternal and left lower scapular region.4 AL positioning involved placement at the cardiac apex and right infraclavicular region. Five RCTs used biphasic cardioversion. The mean patient age was 64 years, and 32% of patients were female. Most RCTs included patients with persistent AF, except for one which had 20% with paroxysmal AF.4 Anti-arrhythmic choice varied.

There was no difference in cardioversion success between the AP and AL pad position (86.6% vs. 87.9%, risk ratio: 1.00; 95% confidence interval [CI]: 0.9 to 1.1). Meta-regression demonstrated no difference by body mass index, left atrial diameter, valvular heart disease, or AF duration. Subgroup analysis found no difference in monophasic or biphasic cardioversion. Among secondary outcomes there was no difference in success at low energy, in number of delivered shocks, or in mean energy delivered. AP pad position was associated with lower transthoracic impedance (standardized mean difference: -0.3 ohms; 95% CI: -0.5 to -0.1).

Caveats

While this systematic review found no difference in successful cardioversion for AF using AP or AL pad positioning, there are several limitations. There was significant heterogeneity in study design, setting, and outcome. The sequence and escalation of shocks varied widely or was not reported, and the included studies provide little detail of the study setting (e.g., emergency department, inpatient setting). While all studies used restoration of sinus rhythm, the time threshold varied or was not specified. In addition, six RC Ts included only persistent AF, which is less responsive to electrical cardioversion. Only patients undergoing elective cardioversion were included. Finally, numbers were small and limited for useful subgroup analysis.

Importantly, monophasic waveform defibrillators are not routinely utilized in North America as of 2023. Of the included studies evaluating biphasic shocks, two studies found no difference with AP and AL positioning, while two others found AL positioning to be superior. The largest study used biphasic shocks with a step-up energy strategy and found AL positioning to be superior.410 However, no difference was seen at energy levels >200 J.10 Of note, a prospective RCT including 244 ED patients with paroxysmal AF published in 2020 found no difference in AL versus AP pad positioning using biphasic shocks at ≥200 J.11

The original manuscript was published in Academic Emergency Medicine as part of the partnership between TheNNT.com and AEM.

Author

Brit Long, MD; Michael Gottlieb, MD
Supervising Editors: Shahriar Zehtabchi, MD

Published/Updated

January 19, 2023