Two studies — EARLY-AF and STOP AF First — indicate that catheter ablation, using cryoablation technology (Medtronic), could be the first-line rhythm treatment for atrial fibrillation (AF). They both showed that cryoablation was more effective at reducing recurrent episodes of AF than antiarrhythmic drugs when used as an initial treatment for people with paroxysmal AF. These data, potentially, could change how AF is treated. Current guidelines advise that ablation should only be used after antiarrhythmic drugs have not worked.
Writing in the New England Journal of Medicine, EARLY-AF authors Dr Jason G Andrade (Vancouver General Hospital, Vancouver, Canada) and colleagues note: “Catheter ablation is superior to antiarrhythmic drugs in maintaining sinus rhythm and improving quality of life in patients in whom drugs have already failed.” However, they add that evidence for ablation being a more effective first-line treatment (i.e. used before, rather than after, drug treatment) is lacking, explaining “previous trials of early catheter ablation with radiofrequency energy have not been conclusive and have been limited by a high incidence of recurrent arrhythmia, complications, and crossover”.
Therefore, Andrade et al conducted EARLY-AF to provide further evidence. Dr Oussama M Wazni (Cleveland Clinic, Cleveland, USA) and colleagues performed the STOP AF First trial for similar reasons. Also writing in the New England Journal of Medicine, they comment: “Our goal was to evaluate the efficacy and safety of cryoballoon ablation as compared with drug therapy as an initial treatment strategy in patients with symptomatic paroxysmal atrial fibrillation.”
The primary endpoint of EARLY AF was the first recurrence of any atrial tachyarrhythmia (atrial fibrillation, atrial flutter, or atrial tachycardia) lasting 30 seconds or longer between 91 and 365 days after the initiation of treatment (ablation or antiarrhythmic drugs); the primary endpoint in STOP AF First was treatment failure at 12 months (defined as freedom from a composite of initial failure of the ablation procedure; any subsequent atrial fibrillation surgery or ablation in the left atrium; or atrial arrhythmia recurrence).
According to Andrade et al, in EARLY AF, freedom from the primary endpoint occurred significantly more often in people who received ablation (154) than in those who received antiarrhythmic drugs (149): 57.1% vs. 32.2% (p<0.001). Wazini et al report that, in STOP AF First, “the percentage of patients with treatment success at 12 months was 74.6% in the ablation group (103 overall) and 45% in the drug therapy group (99 overall) (p<0.001)”. Although the studies were looking at different outcomes, and used different intensities of arrhythmia monitoring, they both suggest that catheter ablation (with cryoablation) is a more effective first-line approach than antiarrhythmic drug therapy (by reducing the rate of recurrence by approximately 50%).
Both sets of authors also looked at the safety of ablation compared with drug treatment, with both finding a similar incidence of serious adverse events (aka complications) with ablation and with antiarrhythmic drug treatments. “Although antiarrhythmic drugs are not benign, we acknowledge that an invasive procedure is associated with more upfront risk than medical therapy,” Andrade et al comment.
Dr Andrade reports that EARLY-AF Study also examined symptom status and quality of life. While all patients enrolled in the study improved following treatment initiation, patients randomised to ablation had a significantly greater improvement in quality of life and were more likely to be asymptomatic at one year.
Concluding, Andrade et al states: “Catheter cryoballoon ablation resulted in a significantly lower rate of recurrence of atrial tachyarrhythmia, as assessed by continuous cardiac rhythm monitoring, than antiarrhythmic drug therapy.” In their conclusion, Wazni et al comment: “Cryoballoon ablation was superior to antiarrhythmic drug therapy for the prevention of atrial arrhythmia recurrence in patients with paroxysmal atrial fibrillation who had not previously received rhythm control treatment.” Furthermore, Wazni et al observe: “Our trial provides additional evidence supporting the use of ablation as an initial first-line treatment.”
A study by itself, or even two studies, does not lead to a change in guidelines (which, in turn, affect how a condition is managed). However, both EARLY-AF and STOP AF will likely be taken into consideration — along with other studies — the next time guidelines for the management of AF are reviewed (usually every four years). Therefore, depending on the findings of other studies, these studies could lead to ablation becoming a first-line treatment for AF.
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