Impact of electrical shock waveform and paddle positions on efficacy of direct current cardioversion for atrial fibrillation

Abstract

Objective. Direct-current electrical cardioversion is the main method for the conversion of atrial fibrillation. Its success depends on many factors. In several studies, biphasic shock waveforms have been demonstrated to be superior to monophasic shocks for termination of atrial fibrillation; however, information about impact of paddle position is controversial. Initial energy level is an object of discussions. The aim of the study was to compare a truncated exponential biphasic waveform with monophasic damped sine waveform and antero-lateral with antero-posterior paddle positions for cardioversion of atrial fibrillation, to determine its impact on early reinitiation of atrial fibrillation. Material and methods. A total of 224 consecutive patients with atrial fibrillation underwent electrical cardioversion with biphasic (Bi, n=112) or monophasic (Mo, n=112) shock waveform in a randomized fashion. The position of hand-held paddle electrodes was randomly selected in both groups to be anterior-lateral and anterior-posterior. Energies used were 100–150–200–300–360 J (Bi) or 100–200–300–360 J (Mo). If monophasic shock of 360 J was ineffective, we used biphasic shock of 360 J. Early recurrent atrial fibrillation (ERAF) was defined as a relapse of atrial fibrillation within 2 min after a successful cardioversion, acute recurrent – within 24 h. Results. Two study groups (Bi vs Mo) did not differ with regard to age, body mass index, duration of AF episode (mean 98±147 days for the Bi group and 80±93 days for the Mo group, P=0.26), underlying heart disease, left atrial diameter, left ventricular ejection fraction. In the Mo group, more patients used amiodarone (59.82% vs 41.97%, P=0.002), in the Bi group more patients used propafenone (16.07% vs 8.93%, P=0.033). Cardioversion success rate was 97.32% in the Bi group and 79.46% in the Mo group (P<0.001). After biphasic shock of 360 J in Mo group, the cumulative success rate was 99.11%. Mean delivered energy and mean number of shocks were significantly lower in the Bi group (198.5±204.4 J, 1.5±0.9 shocks vs 489.1±464.2 J, 2.4±1.5 shocks). The efficacy of first shock was 66.96% in the Bi group and 37.5% in the Mo group (P<0.0001). Incidence of ERAF was 4.46% in both groups. Paddle position had no impact on efficacy of cardioversion and ERAF. Conclusions. For the cardioversion of atrial fibrillation, biphasic shock waveform has a higher success rate than monophasic shock waveform. We did not observe the influence of paddle positions on efficacy of cardioversion. Shock waveform and paddle position had no impact on ERAF. We recommend starting with biphasic energy of 150 J and monophasic of not less than 200 J for cardioversion of atrial fibrillation.

The Efficacy of Pad Placement for Electrical Cardioversion of Atrial Fibrillation/Flutter: A Systematic Review

“…Twenty‐five studies were selected as potentially relevant and accessed for full‐text review, and the remaining 763 studies were excluded for various reasons. Twelve studies were excluded after full‐text review, while the remaining 13 studies were included in the review involving 836 patients receiving A‐P and 856 patients receiving A‐L pad placement . One of the included studies was only found in the bibliography of several included studies.…”

“…One of the included studies was only found in the bibliography of several included studies. Google Translate was used to translate one Spanish and one Lithuanian paper to English. Of the 12 excluded studies, 11 were not prospective randomized or controlled, and one did not compare A‐P versus A‐L pad placement.…”

Part 6: Defibrillation

“…One study showed that paddles/pads should be placed under the breast tissue (LOE 5) 33 and 2 studies showed that hirsute males should be shaved before the application of pads (LOE 5). 34,35 Of the 36 studies reviewed, only 4 examined biphasic waveforms (LOE 5) 18,25,29,36 that have gained widespread use.…”

“…Most studies evaluate cardioversion (eg, AF) or secondary end points (eg, TTI). Eleven studies (LOE 5) [15][16][17][18][19][20][21][22][23][24][25] found all 4 positions (anterior-apex, anteriorposterior, anterior-left infrascapular, anterior-right infrascapular) to be equally effective in defibrillation (for VF/pulseless VT) or elective AF cardioversion success. Four studies support the anteriorposterior position (LOE 5), 26 -30 1 study supports the anterior-lateral position (LOE 5), 31 and 1 study supports the anterior-apex position (LOE 5).…”

Part 6: Electrical Therapies

“…[71][72][73][74][75] There are no studies directly pertaining to placement of pads/paddles for defibrillation success with the end point of ROSC. All 4 positions are equally effective in shock success.…”