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.