BOSTON – Ablation bested antiarrhythmic drugs at reducing the incidence of time to first recurrence of atrial arrhythmias in patients with paroxysmal atrial fibrillation, results of a randomized, multicenter trial showed.
In the study, radiofrequency catheter–based pulmonary vein isolation was associated with a 44% relative risk reduction, compared with antiarrhythmics drugs in the primary end point of time to first recurrence of symptomatic or asymptomatic atrial fibrillation (AF), atrial tachyarrhythmia (AT), or atrial flutter (AFL), reported Dr. Carlos A. Morillo, coprincipal investigator of the RAAFT-2 (Radiofrequency Ablation vs. Antiarrhythmic Drugs as First-Line Treatment of Symptomatic Atrial Fibrillation) study at the annual meeting of the Heart Rhythm Society.
"Radiofrequency catheter pulmonary vein isolation achieved a significant reduction in all primary efficacy outcomes and most secondary outcomes with similar rates of success," said Dr. Morillo, a professor of cardiology at McMaster University in Hamilton, Ont.
"It certainly is very impressive that in these patients who for the first time have atrial fibrillation, they can do better with a strategy of ablation as a first-line therapy, compared to antiarrhythmic drugs. It’s only one trial, however, and it has to be validated, and we have to see how it carries forward, not only at the 1- or 2-year mark but over the long term," Dr. Richard I. Fogel of the St. Vincent Medical Group, Indianapolis, commented in an interview.
Dr. Fogel moderated the late-breaking abstract session at which these data were presented but was not involved in the study.
Previous studies have shown that ablation of atrial fibrillation results in about a 66% relative risk reduction in recurrence, but most studies have focused on patients with atrial fibrillation refractory to one or more antiarrhythmic drugs, Dr. Morillo noted.
The RAAFT-2 investigators enrolled 127 patients with symptomatic, recurrent paroxysmal AF lasting more than 30 seconds who had at least four episodes within the prior 6 months, with at least one of the episodes documented by Holter monitor, 12-lead ECG, event monitor, or rhythm strip.
In the intention-to-treat population, 66 patients (mean age, 56.3 years) were assigned to receive ablation, and 61 (mean age, 54.3 years) were allocated to receive antiarrhythmic drugs for treatment and follow-up, including flecainide (Tambocor), propafenone (Rythmol), dronedarone (Multaq), amiodarone (Cordarone), dofetilide (Tikosyn), and sotalol (Betapace).
About three-fourths of patients in each group were men, and about 87% had paroxysmal AF, with the remaining patients having persistent AF.
Among patients assigned to ablation, the mean number of AF episodes before enrollment was 47.7, and among patients assigned to antiarrhythmic drugs, enrollment was 33.
In the ablation group, 65 of 66 had the ablation performed. During follow-up one patient was lost to follow-up, nine received a second ablation, and seven were crossed over to antiarrhythmic drugs. In the drug group, 60 of 61 were started on drugs. One patient in this group was also lost follow-up, 36 discontinued antiarrhythmic drugs, and 26 were crossed over to ablation.
At 2-year follow-up, 72% of patients in the antiarrhythmic drug group reached the primary efficacy outcome (time to first recurrence of symptomatic or asymptomatic AF/AT/AFL), compared with 55% in the catheter ablation group, for a statistically significant risk reduction of 44%.
Looking at symptomatic AF/AT/AFL only, the proportion of patients with a first recurrence at 2 years was 59% and 47% for the ablation and medical therapy groups, respectively, for a significant 48% relative risk reduction.
In an analysis conducted to determine whether the interventions reduced the frequency of the primary outcome, the authors compared the percentage of transtelephonic monitor (TTM) transmissions indicating any recurrence of the arrhythmias. In all, 6.6% of transmissions in catheter ablation patients showed recurrence, compared with 14.7% of transmission from the antiarrhythmic drug group, yielding a highly significant risk reduction of 66% (P = .0001).
"Of note, when we excluded the transtelephonic monitor, we couldn’t show any [significant] difference in recurrence of the primary outcome – 31% in the antiarrhythmic drug and 24% in the catheter ablation – highlighting the need of very strict monitoring in these patients to be able to define a successful outcome."
Reported patient quality of life in both groups improved over baseline, and was not significantly different between the groups.
For the primary safety end point, there were no deaths in either group at 2 years. Cardiac tamponade was seen in 6.2% of patients in the ablation group, and severe pulmonary stenosis of 70% or greater in 1.5%. There were no cases of atrioesophageal fistula, thromboembolism, vascular complications, or phrenic nerve injury.
For patients on antiarrhythmic drugs, syncope occurred in 3.3%, atrial flutter with 1:1 conduction in 1.6%, and other significant advents leading to discontinuation of drug therapy in 14.3%.