SAN DIEGO – Catheter ablation proved superior to amiodarone for treatment of persistent atrial fibrillation in patients with systolic heart failure in the randomized AATAC-AF trial.
The rate of the primary study endpoint – freedom from recurrent AF through 26 months of prospective follow-up– was 70% in the catheter ablation group, twice the 34% rate with amiodarone, Dr. Luigi Di Biase reported at the annual meeting of the American College of Cardiology. After covariate adjustment, the investigators found that recurrence was 2.5 times more likely in the patients treated with amiodarone.
But he added a major caveat: pulmonary vein antrum isolation (PVI) alone was no better than the antiarrhythmic drug. The high overall treatment success rate seen with catheter ablation in the trial was achieved by operators who performed PVI plus some additional form of ablation of their own choosing, such as elimination of non–pulmonary vein triggers, ablation of complex fractionated electrograms, and/or additional linear ablation lesions, according to Dr. Di Biase, head of electrophysiology at the Albert Einstein College of Medicine, New York.
AATAC-AF (Ablation versus Amiodarone for Treatment of Atrial Fibrillation in Patients with Congestive Heart Failure and an Implanted ICD/CRTD) was a multicenter, prospective, randomized trial involving 203 patients with persistent AF and heart failure with reduced ejection fraction. Patients randomized to ablation had to receive PVI at a minimum; operators could perform additional ablation according to their preference. Twenty percent of patients randomized to ablation received PVI alone; 80% underwent additional posterior wall and non–pulmonary vein trigger ablation. The 26-month rate of freedom from recurrence of AF was 36% in patients who received PVI alone and 79% in those who underwent more extensive ablations. A particular strength of the AATAC study was that all participants had an implantable cardioverter-defibrillator and/or cardiac resynchronization therapy device, permitting detection of AF with a much higher degree of accuracy than possible in most AF ablation trials.
Any recurrent AF episodes during the first 3 months of follow-up were excluded from the analysis, regardless of whether patients were in the ablation or amiodarone arms, in accord with the 3-month blanking period that’s standard among electrophysiologists. Patients averaged 1.4 ablation sessions during the first 3 months of the trial.
Regardless of treatment, patients in whom AF did not recur showed significantly greater improvement in left ventricular ejection fraction, exercise capacity, and heart failure–related quality of life.
In addition, all-cause mortality during follow-up was significantly lower in the ablation group: 8%, compared with 18% in patients assigned to amiodarone. Moreover, the rate of hospitalization for arrhythmia or worsening heart failure was 31% in the ablation group versus 57% in patients on amiodarone. The economic implications of this sharp reduction in hospitalizations will be the subject of further study, according to Dr. Di Biase.
Dr. Luigi Di Biase
Also noteworthy was the finding that seven patients had to discontinue amiodarone due to serious side effects: four because of thyroid toxicity, two for pulmonary toxicity, and one owing to hepatic dysfunction, he continued.
Discussant Dr. Richard I. Fogel, current president of the Heart Rhythm Society, commented that “the 70% arrhythmia-free follow-up was a little surprising to me.”
“That seems a little bit high, particularly in a group with persistent atrial fibrillation,” observed Dr. Fogel, who is chief executive officer at St. Vincent Medical Group, Indianapolis.
Dr. Di Biase attributed the high success rate to two factors: One, only highly experienced operators participated in AATAC, and two, most of them weren’t content to stick to PVI alone.
“If you try to do a more extensive procedure addressing non–pulmonary vein triggers in other areas in the left atrium, the success rate is increased by far,” the electrophysiologist said.
As for a possible mechanism for the mortality benefit seen with ablation, “several studies have shown that in a population with heart failure with reduced ejection fraction, atrial fibrillation is an independent predictor of mortality,” Dr. Di Biase said. “So I believe that staying in sinus rhythm may have affected the long-term mortality. If you have a treatment that reduces the amount of time in atrial fibrillation, you may reduce mortality.”
While catheter ablation is an increasingly popular treatment strategy in patients with drug-refractory paroxysmal AF, it has been understudied in the setting of AF and comorbid heart failure. These two conditions are commonly coexistent, and they feed on each other in a destructive way: AF worsens heart failure, and heart failure tends to make AF worse.
AATAC was funded by the participating investigators and institutions without external financial support. Dr. Di Biase reported serving as a consultant to Biosense Webster and St. Jude Medical and serving as a paid speaker for Atricure, Biotronik, Medtronic, Boston Scientific, and Epi EP.