Elsevier

The Lancet

Volume 395, Issue 10221, 1–7 February 2020, Pages 339-349
The Lancet

Articles
Electrical versus pharmacological cardioversion for emergency department patients with acute atrial fibrillation (RAFF2): a partial factorial randomised trial

https://doi.org/10.1016/S0140-6736(19)32994-0Get rights and content

Summary

Background

Acute atrial fibrillation is the most common arrythmia treated in the emergency department. Our primary aim was to compare conversion to sinus rhythm between pharmacological cardioversion followed by electrical cardioversion (drug–shock), and electrical cardioversion alone (shock-only). Our secondary aim was to compare the effectiveness of two pad positions for electrical cardioversion.

Methods

We did a partial factorial trial of two protocols for patients with acute atrial fibrillation at 11 academic hospital emergency departments in Canada. We enrolled adult patients with acute atrial fibrillation. Protocol 1 was a randomised, blinded, placebo-controlled comparison of attempted pharmacological cardioversion with intravenous procainamide (15 mg/kg over 30 min) followed by electrical cardioversion if necessary (up to three shocks, each of ≥200 J), and placebo infusion followed by electrical cardioversion. For patients having electrical cardioversion, we used Protocol 2, a randomised, open-label, nested comparison of anteroposterior versus anterolateral pad positions. Patients were randomly assigned (1:1, stratified by study site) for Protocol 1 by on-site research personnel using an online electronic data capture system. Randomisation for Protocol 2 occurred 30 min after drug infusion for patients who had not converted and was stratified by site and Protocol 1 allocation. Patients and all research and emergency department staff were masked to treatment allocation for Protocol 1. The primary outcome was conversion to normal sinus rhythm for at least 30 min at any time after randomisation and up to a point immediately after three shocks. Protocol 1 was analysed by intention to treat and Protocol 2 excluded patients who did not receive electrical cardioversion. This study is registered at ClinicalTrials.gov, number NCT01891058.

Findings

Between July 18, 2013, and Oct 17, 2018, we enrolled 396 patients, and none were lost to follow-up. In the drug–shock group (n=204), conversion to sinus rhythm occurred in 196 (96%) patients and in the shock-only group (n=192), conversion occurred in 176 (92%) patients (absolute difference 4%; 95% CI 0–9; p=0·07). The proportion of patients discharged home was 97% (n=198) versus 95% (n=183; p=0·60). 106 (52%) patients in the drug–shock group converted after drug infusion only. No patients had serious adverse events in follow-up. The different pad positions in Protocol 2 (n=244), had similar conversions to sinus rhythm (119 [94%] of 127 in anterolateral group vs 108 [92%] of 117 in anteroposterior group; p=0·68).

Interpretation

Both the drug–shock and shock-only strategies were highly effective, rapid, and safe in restoring sinus rhythm for patients in the emergency department with acute atrial fibrillation, avoiding the need for return to hospital. The drug infusion worked for about half of patients and avoided the resource intensive procedural sedation required for electrical cardioversion. We also found no significant difference between the anterolateral and anteroposterior pad positions for electrical cardioversion. Immediate rhythm control for patients in the emergency department with acute atrial fibrillation leads to excellent outcomes.

Funding

Heart and Stroke Foundation of Canada and the Canadian Institutes of Health Research.

Introduction

Acute atrial fibrillation is the most common arrhythmia requiring treatment in the emergency department.1, 2 Atrial fibrillation is characterised by disorganised atrial electrical depolarisation leading to an irregular and rapid heart rate. Acute atrial fibrillation generally refers to symptomatic, recent-onset episodes (first detected, recurrent paroxysmal, or recurrent persistent episodes) where the duration is less than 48 h and cardioversion is a safe option.3 We estimate that in Canada and the USA, 430 000 visits to the emergency department annually are due to acute atrial fibrillation.4, 5

The two major approaches to emergency department treatment of this arrythmia are rate control or rhythm control. In rate control, medications are used to reduce the heart rate, but the patient remains in atrial fibrillation at the time of discharge or admission. With the rhythm control approach, patients are cardioverted back to normal sinus rhythm with drugs or electrical cardioversion (direct-current [DC] cardioversion), and are usually discharged home within a few hours. There is little evidence regarding many important aspects of acute atrial fibrillation management in the emergency department and there is equipoise for most facets of early care.3, 6, 7 Few randomised trials have addressed key acute atrial fibrillation questions, such as whether patients should be treated with rate control or rhythm control, whether rhythm control should proceed initially with drugs or with DC cardioversion, and whether DC cardioversion electrode pads should be placed anteroposterior or anterolateral. Much variation in practice exists among Canadian and US physicians.8, 9 Although many physicians believe that rhythm control is better for the patient, to our knowledge, no trials have ever compared rate control with rhythm control for patients with acute atrial fibrillation.8, 10, 11

Research in context

Evidence before this study

Regarding Protocol 1, comparison of electrical versus pharmacological cardioversion for acute atrial fibrillation, we searched PubMed from inception to Oct 1, 2019, using the search terms “atrial fibrillation” and “pharmacological cardioversion”. We could find no published studies comparing electrical with pharmacological cardioversion. A trial by Pluymaekers and colleagues compared two approaches to early rhythm control: same-day cardioversion and next-day cardioversion. This study used both chemical and electrical cardioversion strategies, but the two were not compared. Some observational studies have confirmed the effectiveness of early rhythm control but without distinguishing between the value of pharmacological and electrical cardioversion. Other emergency department studies of rhythm control for acute atrial fibrillation have been small or have not compared pharmacological and electrical cardioversion. Previous studies have confirmed the effectiveness and safety of procainamide for acute atrial fibrillation.

Regarding Protocol 2, a comparison of anterolateral and anteroposterior pad positions, we searched PubMed from inception to Oct 1, 2019, using the search terms “atrial fibrillation” and “pad position”, and identified five previous randomised trials that used contemporary biphasic devices, although most patients had persistent rather than acute atrial fibrillation. Of these European studies, only one used the right infraclavicular anteroposterior position commonly used in Canada and the USA, and only one started shocks as high as 150 J. Three studies showed no difference in conversion between the two pad positions and two showed a higher proportion of patients converting using the anterolateral position.

Added value of this study

This clinical trial found no significant difference between using either a drug–shock or a shock-only approach as an immediate strategy to treat acute atrial fibrillation in the emergency department; both approaches were highly effective, rapid, and safe in restoring sinus rhythm. The drug–shock strategy was shown to be more effective for patients with first episodes of atrial fibrillation and for patients younger than 70 years than it was for other patients. Both anterolateral and anteroposterior pad positions are highly effective for electrical cardioversion.

Implications of all the available evidence

The most important finding from this study is that either approach to immediate rhythm control in the emergency department leads to a very high proportion of patients being discharged in sinus rhythm without serious adverse events. Patients can be rapidly cardioverted in the emergency department, resolving their acute symptoms and enabling discharge home. This avoids unnecessary hospital admission or next-day re-evaluation by cardiologists. This obviates the need for anticoagulation in low-risk patients and the need for medication prescriptions to control heart rate. Patients can quickly return to normal activities and avoid extended stays in crowded emergency departments. We believe that the procainamide infusion leading to rapid conversion in more than 50% of patients is an important advantage of the drug–shock approach. This approach allows physicians to attend to other patients during the procainamide infusion and frequently avoids the need for procedural sedation, which might lead to serious adverse events. Sedation also requires explicit consent and the continuous attendance of additional health-care providers. Nevertheless, the choice between pharmacological and electrical cardioversion should be a shared decision between the patient and the physician. We also found no significant difference between the anterolateral and anteroposterior pad positions for electrical cardioversion. If initial attempts fail, many physicians suggest switching to the other position and applying firm pressure to the pads to reduce transthoracic impedance.

For acute atrial fibrillation rhythm control in the emergency department, some physicians prefer to start with drugs and then move to DC cardioversion if necessary (drug–shock strategy). Other physicians prefer to start immediately with DC cardioversion (shock-only strategy). We have shown that emergency department physicians are equally divided in their use of these two competing cardioversion strategies.8, 10, 11 We have also seen much variation in DC cardioversion pad placement in emergency departments.11 Our primary aim was to compare conversion to sinus rhythm between two strategies: (1) attempted pharmacological cardioversion with intravenous procainamide followed by DC cardioversion if necessary (drug–shock), and (2) DC cardioversion alone (shock-only). Our secondary aim was to compare the anteroposterior versus the anterolateral pad positions in DC cardioversion.

Section snippets

Study design

We did a partial factorial study of two protocols at 11 academic emergency departments (appendix p 4). The primary protocol (Protocol 1) was a randomised, blinded, placebo-controlled comparison of attempted pharmacological cardioversion with intravenous procainamide (15 mg/kg over 30 min) followed by electrical cardioversion (up to three shocks, each of ≥200 J) if necessary, versus placebo infusion followed by electrical cardioversion. For the subset of patients who required electrical

Results

Patients were enrolled at 11 different emergency departments from July 18, 2013, to Oct 17, 2018. Of 1188 eligible patients, 582 did not want to participate, 210 were not approached, and 396 were enrolled (figure 2). None were lost to follow-up for the primary outcome. Patients in the drug–shock (n=204) and shock-only (n=192) groups were well balanced for demographics, clinical characteristics, and investigation results (table 1; appendix p 1). The mean age of the patients was 60 years, 260

Discussion

This large, randomised, blinded clinical trial found no significant difference between the strategy of attempting chemical cardioversion first and a strategy of proceeding directly to electrical cardioversion for patients with acute atrial fibrillation in the emergency department. Both the drug–shock and shock-only strategies were highly effective in safely and quickly returning patients to normal sinus rhythm. Almost all patients were discharged home from the emergency department, usually

Data sharing

We do not have consent from patients or hospital research ethics boards to share individual case data. We will, however, make summary data available to corresponding investigators.

References (45)

  • PE Fenster et al.

    Conversion of atrial fibrillation to sinus rhythm by acute intravenous procainamide infusion

    Am Heart J

    (1983)
  • GE Kochiadakis et al.

    A comparative study of the efficacy and safety of procainamide versus propafenone versus amiodarone for the conversion of recent-onset atrial fibrillation

    Am J Cardiol

    (2007)
  • S Siaplaouras et al.

    Randomized comparison of anterolateral versus anteroposterior electrode position for biphasic external cardioversion of atrial fibrillation

    Am Heart J

    (2005)
  • T Muñoz-Martínez et al.

    Electrode position in elective electrical cardioversion of atrial fibrillation. A randomized study

    Med Intensiva

    (2010)
  • B Zhang et al.

    Anterior-posterior versus anterior-lateral electrode position for external electrical cardioversion of atrial fibrillation: a meta-analysis of randomized controlled trials

    Arch Cardiovasc Dis

    (2014)
  • KE Airaksinen et al.

    Thromboembolic complications after cardioversion of acute atrial fibrillation: the FinCV (Finnish CardioVersion) study

    J Am Coll Cardiol

    (2013)
  • IG Stiell et al.

    Safety of urgent cardioversion for patients with recent-onset atrial fibrillation and flutter

    Can J Cardiol

    (2015)
  • CT January et al.

    2019 AHA/ACC/HRS focused update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society

    J Am Coll Cardiol

    (2019)
  • S Connors et al.

    Management of supraventricular tachycardia in the emergency department

    Can J Cardiol

    (1997)
  • SR Pitts et al.

    National Hospital Ambulatory Medical Care Survey: 2006 emergency department summary

    Natl Health Stat Report

    (2008)
  • TB Chan et al.

    Emergency department services in Ontario 1993-2000

    (2001)
  • Canadian Cardiovascular Society atrial fibrillation guidelines 2010

    Can J Cardiol

    (2011)
  • Cited by (62)

    • Anteroposterior Versus Anterolateral Electrode Position for Direct Current Cardioversion of Atrial Fibrillation: A Meta-Analysis of Randomised Controlled Trials

      2022, Heart Lung and Circulation
      Citation Excerpt :

      Of these, 51 were excluded based on title and abstract content. After screening the full text of the remaining 22 articles, 12 studies met inclusion criteria (Figure 1) [7–18]. Across the 12 RCTs (Table 1), a total of 2,046 patients were randomised to antero-posterior (n=1,009) or antero-lateral (n=1,037) electrode positioning.

    View all citing articles on Scopus
    View full text