Scheuermeyer FX, Andolfatto G, Christenson J, et al. A multicenter randomized trial to evaluate a chemical-first or electrical-first cardioversion strategy for patients with uncomplicated acute atrial fibrillation. Acad Emerg Med. 2019;26(9):969-981.
This article discusses a multicenter randomized study comparing chemical-first and electrical-first cardioversion management in the emergency department (ED) for patients with uncomplicated atrial fibrillation (AF) occurring for <48 hours. The study included 84 patients who were randomized to procainamide infusion or electrical cardioversion as the first treatment. If either strategy was unsuccessful in controlling the rhythm, the other strategy was employed. The results of the study indicate that both strategies are successful, but utilizing electrical cardioversion first resulted in shorter time to normal sinus rhythm and shorter length of stay (LOS) in the ED.
In Canada, general management of uncomplicated AF includes either chemical cardioversion followed by electrical cardioversion, if needed, or electrical cardioversion followed by chemical cardioversion, if needed. Data indicate that these strategies are used fairly equally in Canada, with the chemical-first approach utilized slightly more often. Upon conversion to and maintenance of normal sinus rhythm, patients can be discharged home. The data on the individual strategies indicate that both are safe and effective, but data comparing the two are lacking. The goal of this study was to assess whether one approach brings the patient back to normal sinus rhythm more quickly than the other.
This study took place in 6 urban Canadian EDs of varied capacity and resources (eg, centers with no on-site cardiologists vs centers with access to electrophysiology labs, catheterization labs, and cardiac surgeons). Study patients were recruited when research assistants were available, and all sites utilized resident trainees, with attending physicians determining study eligibility and timing of rhythm control. Patients between the ages of 18 and 75 years were eligible if they had AF of <48 hours duration, a CHADS2 score (based on the presence of congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, prior stroke) of 0 or 1, and were on anticoagulation therapy. Patients were excluded if they had an incidental finding of AF, hemodynamic instability, atrial flutter, acute underlying illness, a recent cardiac procedure, or were intoxicated or going through withdrawal from alcohol or drugs.
In the chemical-first cardioversion group, procainamide was utilized at a recommended dose of 17 mg/kg, up to 1500 mg infused over 1 hour. Treating physicians were informed that chemical cardioversion for AF has been shown to result in cardioversion of half of patients within 1 hour and 90% of patients within 2 hours of treatment. If a patient did not convert to normal sinus rhythm with procainamide, physicians allowed a median of 110 minutes to elapse before initiating sedation for electrical cardioversion. In the electrical-first cardioversion group, patients were administered propofol until adequate sedation was reached. The recommended sequence for electrical cardioversion was 100 to 150 to 200 Joules, with a maximum of 3 shocks. Procainamide was given if the third shock was unsuccessful in converting the patient.
The primary outcome for each management strategy addressed in this study was the percentage of patients who were discharged from the ED within 4 hours of triage registration. In an effort to decrease any bias in relation to timing of treatments, the treating attending physicians were not made aware of this outcome assessment. The secondary outcomes included other patient management intervals, adverse events in the ED, and 30-day outcomes. See Table 1 for the outcome results of this study.
The results of this study indicate that use of an electrical-first strategy for management of uncomplicated AF allows for more patients to be discharged from the ED within 4 hours and results in a short median LOS in the ED (by 1.2 hours) than use of a chemical-first strategy. The authors noted that the study may aid in clinical decision-making by showing that attempting to cardiovert patients using the electrical strategy first may work more quickly than using the chemical strategy first. Half of the patients who underwent electrical cardioversion first were discharged within 1 hour, with a lower number of chemical cardioversion patients discharged in the same timeframe. The authors note that the number of ED revisits in the chemical-first group were substantially (but not significantly) higher than the electrical-first cardio-version group, and state that there might be long-term benefits with an electrical-first approach.
Limitations of the study were assessed by the authors, who noted potential difficulty generalizing the results to EDs outside the urban setting and those without physicians experienced with the procedures. They also noted that LOS in the ED could have been affected by many variables, including other critically ill patients in the ED, lack of availability of staff, and triage priorities. Other factors included established departmental protocols and clinical judgment. Additionally, the authors note that the study was not powered to assess serious outcomes fully and that one-third of patients who were eligible declined to participate in the study. Patient and physician satisfaction and costs were also not assessed.
AF is one of the most commonly encountered dysrhythmias in the ED. Although it is not typical practice to cardiovert AF in the ED in the United States, this study demonstrates that it is reasonable and effective in the appropriate patient population.
This study was undertaken in 6 different urban EDs in Canada, at both community and tertiary care sites, increasing the reproducibility of this study. The study is applicable to multiple settings and patient populations, as it covers a wide age range (patients aged between 18 and 75 years) who are low-risk, with a CHADS2 score of 0 or 1. The study had strict inclusion and exclusion criteria, which is helpful in limiting confounding variables, but also limits the number of eligible patients. Patients in both arms were balanced equally in age, gender, acuity, and past medical history. Identification of adverse effects were based on standardized World Society of Anesthesia guidelines.
Although the primary outcome (discharge from the ED within 4 hours) was not a patient-centered outcome, the secondary outcomes took into account LOS, adverse events, 30-day ED revisits, and hospitalizations. The study had excellent follow-up, and the investigators were able to contact almost all patients at days 3 and 30 to assess the secondary outcomes.
Given the methods of administering treatments, neither physicians nor patients could be blinded to the study. Physicians were also allowed to exercise their clinical judgment, which could have biased the allocation of patients to the different arms and the results. Registering trial participants was limited to the times when research assistants were on duty, which could have limited the impact and significance of the findings. The study also explored only a single agent for chemical cardioversion, procainamide. Although this aided in standardizing the results, other physicians may have different first-line agent options, which may have decreased the applicability of this study.