LOS ANGELES – A strategy of catheter ablation–based rhythm control in patients with long-standing persistent atrial fibrillation plus heart failure improved cardiopulmonary exercise capacity, quality of life, and neurohormonal status, compared with pharmacologic rate control in a single-center randomized trial.
The majority of improvement seen in these endpoints in the ARC-HF (Catheter Ablation Versus Medical Rate Control for Atrial Fibrillation in Patients With Heart Failure) trial occurred 3-12 months after the initial ablation procedure, Dr. David G. Jones reported at the annual scientific sessions of the American Heart Association.
"This may reflect progressive amelioration of the heart failure syndrome. And our findings may also have prognostic significance," said Dr. Jones of Imperial College London.
Indeed, although clinical outcomes weren’t included in the relatively small ARC-HF study, they were reported in the recently published 1,620-patient HF-ACTION (Exercise Training Program to Improve Clinical Outcomes in Individuals With Congestive Heart Failure) trial (Circ. Heart Fail. 2012;5:579-85). And HF-ACTION showed that every 6% increase in peak oxygen uptake (VO2) was associated with an 8% lower risk of the combined endpoint of cardiovascular mortality or heart failure hospitalization and a 7% reduction in all-cause mortality.
"By comparison, ours was close to a 20% increase in peak VO2 at 1 year with ablation therapy," Dr. Jones observed.
The ARC-HF trial included 51 patients with continuous persistent atrial fibrillation (AF) for an average of 24 months, symptomatic systolic heart failure, and a left ventricular ejection fraction of 35% or less. Because it has been unclear whether restoration of sinus rhythm or pharmacologic rate control is the optimal management strategy in patients with AF and the common comorbidity of heart failure, the investigators randomized participants to catheter ablation of the arrhythmia or to rate control.
The primary endpoint was the change in peak VO2 at 12 months from a baseline of roughly 17 mL/kg per minute. Peak VO2 increased by a mean of 2.0 mL/kg per minute in the 25 patients in the ablation group while declining over time in the rate control group, for an impressive 12-month intergroup difference of 3.07 mL/kg per minute.
The ablation group also displayed significant improvements in quality of life as measured by the Minnesota Living With Heart Failure Questionnaire, as well as neurohormonal status as reflected in a reduction in brain natriuretic peptide levels. Data on other cardiac biomarkers are still being analyzed.
A significant reduction in baseline left atrial dilation was documented in the ablation group at 6 months and maintained at 12 months. The ablation group showed a nonsignificant trend toward improved left ventricular ejection fraction.
Dr. Jones stressed that the ablation procedures were long and challenging. They averaged 333 minutes in duration, including mapping, with fully 80 minutes of fluoroscopy time and 82 minutes of actual ablation.
Seven patients experienced recurrent atrial arrhythmias post ablation; five of them underwent a second ablation procedure and one had a third. The single-procedure success rate in achieving sinus rhythm at 12 months was 72%, with a multiprocedure success rate of 92%.
Of the 26 patients in the rate control group, 2 were in sinus rhythm at 12 months (including 1 patient who crossed over to catheter ablation), and 23 of the remaining 24 were optimally rate controlled, with a resting heart rate below 80 beats per minute and a maximum heart rate below 110 bpm during a 6-minute walk test.
Discussant Dr. Karl-Heinz Kuck called the ARC-HF results "remarkable." So much so, in fact, that he doesn’t think catheter ablation can be recommended for now in patients with long-standing persistent AF and heart failure, because the single-center ARC-HF results are out of step with those reported in observational series. Better, he said, to wait for the results of ongoing, much larger multicenter randomized trials, including CASTLE-AF as well as AMICA, for which he serves as principal investigator.
Among Dr. Kuck’s concerns was the whopping 2.0-mL/kg per minute increase in peak VO2 reported in ARC-HF. To put that in perspective, the major randomized trials of cardiac resynchronization therapy and cardiac contractility modulation therapy for heart failure achieved increases of only 0.7-1.0 mL/kg per minute.
Also, a recent report from Dr. Kuck and his coinvestigators in the Hamburg Sequential Ablation Group, which involved 202 patients who underwent catheter ablation for long-standing persistent AF, showed only 36% were in sinus rhythm at 12 months after a single procedure and 60% after multiple procedures. Those success rates are substantially lower than in ARC-HF, noted Dr. Kuck, head of the cardiology department at St. Georg Hospital, Hamburg, Germany.