Competing Strategies Rapidly Restore Sinus Rhythm in Acute AF
Randomized data provide equal support for pharmacological and electrical cardioversion of acute atrial fibrillation (AF), but also point to a potential advantage for the drug-first strategy in younger patients and those with first AF episodes.
Conversion to sinus rhythm occurred in 96% of patients randomly assigned to intravenous procainamide and up to three shocks, if necessary, and 92% in patients assigned to electrical shock only (P = .07) in the Canadian RAFF2 trial.
Almost all patients were discharged home from the emergency department (97% vs 95%; P = .60).
The drug–shock group had more adverse events, but most were transient hypotension (38 vs 4 events) and none were serious, the authors report February 1 in the Lancet.
“I think this is going to reassure a lot of people and prompt people to probably involve the patient more in the conversation because, before this study, there was a lot of physicians who absolutely believed one strategy was better than the other, and this basically says they are both equally effective,” cosenior author Jeffrey J. Perry, MD, MSc, Ottawa Hospital Research Institute, Ontario, told theheart.org | Medscape Cardiology.
He noted that guidelines leave a great deal of leeway on whether to use rate or rhythm control when managing AF in the emergency department, and that evidence is lacking directly comparing the two cardioversion strategies.
The researchers recruited 396 stable patients with acute AF (mean age, 60 years; 66% men) presenting to 11 Canadian emergency departments, and randomly assigned 192 to shock only and 204 to a continuous infusion of procainamide (maximum dose, 1500 mg).
Procainamide was administered more quickly (over 30 minutes) than in previous studies, using weight-based dosing (15 mg/kg).
“That is what we’re generally using in practice now,” Perry explained. “We found in a previous phase of this study that there was a lot of variation. We worked with our cardiology coinvestigators and they felt quite strongly we should be using the maximal dosage and that there wasn’t any strong reason not to give it at the maximum speed because these patients are being monitored and, if there is any transient hypertension, we can easily address that by slowing down the infusion or giving a small bolus of fluid.”
Procainamide, a class 1A antiarrhythmic, is the most commonly used drug for acute AF in Canada, but is far less popular in the United States.
“I think it’s underappreciated,” Perry observed. “There aren’t a lot of head-to-head trials but, certainly in our experience, it works very effectively and is more effective probably than amiodarone in terms of overall success rate, and likely rapidity of effectiveness as well.”
Procainamide converted 52% of patients in a median time of 23 minutes.
In a priori subgroup analyses, the procainamide-first strategy was significantly more likely to convert patients who presented with a first AF episode vs a repeat episode (100.0% vs 94.2%; Fisher’s exact P = .02) or were younger than 70 vs 70 years or older (98.6% vs 89.7%; X2 P = .01).
In a second protocol, 244 patients who required electrical cardioversion were placed in a nested, randomized comparison of anterolateral vs anteroposterior pad positions.
The comparison showed no difference in conversion between the anterolateral and anteroposterior pad positions (94% vs 92%; P = .68). A median of one shock was required in each group.
At 14-day follow-up, 95% of all patients were still in sinus rhythm, there were no strokes, and one death occurred due to cancer.
Although the short follow-up could have missed subsequent thromboembolic events, 6- and 12-month follow-ups have not shown this to be the case, Perry said.
Advantages of the drug–shock approach are that it allows busy emergency physicians to attend to other patients during the procainamide infusion and frequently eliminates the need for procedural sedation and electrical conversion, which might lead to serious adverse events, the authors note.
Nevertheless, the choice between pharmacological and electrical cardioversion should be a shared decision between the patient and the physician, Perry and colleagues conclude.
Giorgio Costantino, MD, Ospedale Maggiore Policlinico, and Monica Solbiati, MD, PhD, Università degli Studi di Milano, both in Milan, Italy, write in an accompanying editorial that the most important finding is that both strategies are “equally highly effective. The question of how to decide which strategy to use in each individual patient therefore remains.”
The editorialists question whether the drug–shock approach requires less monitoring, as only one patient had a serious adverse event related to the lack of synchronization during electrical cardioversion, but several patients in the drug–shock group had mild adverse events.
The editorialists suggest there is a potential advantage of using flecainide or propafenone for pharmacological conversion, as clinicians can prescribe these drugs for long-term maintenance of sinus rhythm. Procainamide has been associated with lupus when administered orally.
“However, class IA and IC antiarrhythmic drugs are similarly effective for cardioversion, so the study findings could potentially be extended to class IC drugs,” they write.
The study was funded by the Heart and Stroke Foundation of Canada and the Canadian Institutes of Health Research. The authors and editorialists declared no competing interests.