RADAR-AF: HF Source Ablation Does Not Benefit Paroxysmal, Persistent A-fib Patients

DALLAS, TX—In patients with paroxysmal atrial fibrillation (A-fib), treatment with high frequency (HF) source ablation failed to meet noninferiority criteria compared with circumferential pulmonary vein isolation (CPVI) at 6 months, according to results presented November 19, 2013, at the annual American Heart Association Scientific Sessions. In patients with persistent A-fib, a combination of CPVI and HF ablation offered no incremental value with a trend toward more complications.   

For the RADAR-AF trial, researchers led by Felipe Atienza, MD, PhD, of Hospital General Universitario, Gregorio Marañón (Madrid, Spain), randomized 232 patients with paroxysmal A-fib (n = 115) to undergo CPVI (n = 59) or HF ablation only (n = 56). Patients with persistent A-fib (n = 117) were randomized to CPVI with (n = 59) or without (n = 58) HF source ablation.   

The primary endpoint was freedom from A-fib at 6 months post-first ablation procedure off antiarrhythmic medications.   

No Added Benefit  

In the paroxysmal A-fib group, ablating the A-fib drivers failed to show noninferiority vs. pulmonary-vein isolation for the primary endpoint (73% vs. 83%; P = 0.23 for noninferiority). When patients who received additional ablation procedures within 1 year were added to the analysis, both strategies were similar, with freedom from A-fib seen in 69% of each arm at 12 months (P = 0.04 for noninferiority). Ablation was associated with a reduction in severe adverse events compared with CPVI (P = 0.03).   

In persistent A-fib, the combination strategy offered no incremental value over CPVI alone with regard to the primary endpoint (61% vs. 60%; P = 0.941). There was a trend toward increased adverse events when HF source ablation was added (24% vs. 10%; P = 0.050).   

Ablation Argument Still ‘Alive’

“These results offer a novel mechanistic treatment paradigm for paroxysmal atrial fibrillation,” Dr. Atienza said.  

In addition to increasing the study sample size, he indicated he would like the algorithm improved for faster and easier use “because we are mapping point by point, which is time consuming, and at the same time we have to go and review all the required points.”   

Discussing the trial, Mark S. Link, MD, of the Tufts University School of Medicine (Boston, MA), said that even though HF ablation did not improve outcomes in patients with either type of A-fib, “the fact that high frequency source ablation treatment was equivalent to CPVI in paroxysmal atrial fibrillation keeps the A-fib substrate and trigger ablation argument alive as we wait for better tools.  

“There is something to this notion that substrate is important and that there is something in addition to PVI,” he continued. “We just don’t know the best tools in order to know where to ablate the substrate.” 

Source:

Atienza F. Radiofrequency catheter ablation of drivers vs. circumferential pulmonary vein isolation in patients with atrial fibrillation. Presented at: American Heart Association Scientific Sessions; November 19, 2013; Dallas, TX.  

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