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RADAR-AF: High-frequency source ablation safe, effective in patients with paroxysmal AF
High-frequency source ablation was safer than conventional ablation treatment in patients with paroxysmal atrial fibrillation and just as effective, but made no difference in patients with persistent AF, according to findings from the RADAR-AF trial.
Felipe Atienza, MD, PhD, and colleagues evaluated whether high-frequency source ablation (HFSA) is an alternative to circumferential pulmonary vein isolation in patients with paroxysmal AF and an augmentation to circumferential pulmonary vein isolation (CPVI) in patients with persistent AF.
CPVI is a popular therapy for drug-refractory AF because most triggers for AF are located in the pulmonary vein, but “as of now, the procedure is absolutely empirical, not directed to the sources causing AF,” Atienza said during a press conference at AHA 2013. HFSA uses a computer mapping system (Ensite NavX 8.0, St. Jude Medical) to more precisely target abnormal myocardial tissue.
Atienza, of Hospital Gregorio Maranon, Madrid, and colleagues enrolled 115 patients with paroxysmal AF and 117 patients with persistent AF (186 men; mean age, 53 years). In a noninferiority study, patients with paroxysmal AF were randomly assigned to receive CPVI or HFSA. In a superiority study, patients with persistent AF were randomly assigned to receive CPVI or CPVI plus HFSA.
The primary endpoint for all patients was freedom from AF 6 months after the first post-ablation procedure while off antiarrhythmic medications. Patients were assessed by ECG and 48-hour Holter at 3, 6 and 12 months. Secondary endpoints included incidence of complications.
In patients with paroxysmal AF, HFSA was noninferior to CPVI for the endpoint of freedom from AF at 12 months (P=.008), but patients receiving HFSA had a reduced risk for adverse events compared with patients receiving CPVI (P=.028).
In patients with persistent AF, there was no difference between the groups in the primary outcome (CPVI plus HFSA, 61% vs. CPVI, 60%; P=.94), but adverse events occurred more frequently in the CPVI plus HFSA group (24% vs. 10%; P=.05).
“We believe these results may offer a novel mechanistic treatment only directed to paroxysmal AF,” Atienza said at the press conference. “We know that this study is not beneficial for persistent AF, and we still don’t know what we can do beyond [CPVI] in those patients.”
Invited discussant Mark S. Link, MD, of Tufts University School of Medicine, Boston, said that the results for patients with paroxysmal AF “keep the AF and substrate trigger argument alive, and hopefully with further modifications, we’ll come up with better treatments for our patients.” – by Erik Swain
For more information:
Atienza F. LBCT.05. New strategies for atrial fibrillation patients: Rhythm and thrombosis. Presented at: the American Heart Association Scientific Sessions; Nov. 16-20, 2013; Dallas.
Disclosure: Atienza reports financial ties with Boston Scientific, Medtronic and St. Jude Medical Spain. Link reports no relevant financial disclosures.
Perspective
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It’s not a death knell for substrate ablation, but I think we need to figure out a better way to identify substrates. These continuous fractionated electrograms are sites where there might be rotors, but we don’t know that. All we know is that they are fractionated electrograms; whether they are truly the substrate is a question that I think remains unanswered.
One of the things that’s clear is that we can do a good job in AF ablation, but we need to be able to do a better job. That’s the reason for a search for other ablation modifications. We need to both get the technology better and get an improved fundamental understanding of how rotors are reflected on anthrocardiac electrograms. Both of those things are going to be important, and they’ll continue to get better.
We have gotten better, however. Right now, if you look at the procedures, we do a fairly good job with paroxysmal AF; in that, ablation is effective and keeps people mostly out of paroxysmal AF for up to a decade. Is it a completely curative procedure? I don’t think that’s known, but if I had symptomatic paroxysmal AF and you told me I would be free of that for a decade, I think that might be worth a trip to the EP lab.