Three-Dimensional MRI Models in Two Patients with Moderate Structural Remodeling in Patients with Atrial Fibrillation. Image source: Oakes et al. Circulation 2010:119(13):1758-1767.

SAN FRANCISCO—The use of a diagnostic mapping tool helped terminate or slow atrial fibrillation (AF) with less than 10 minutes of ablation, according to the results of the CONFIRM trial presented as a late-breaking clinical trial at this year’s Heart Rhythm Society (HRS). Researchers found that focal impulse and rotor modulation (FIRM) ablation increased two-year freedom of AF by 70 percent.

The study enrolled 103 patients between the ages of 40 and 82 years old. Sixty-seven percent of patients had persistent AF and 33 percent had paroxysmal AF. The researchers split patients into two groups to receive either FIRM-guided ablation for less than 10 minutes per rotor focus followed by a wide-area circumferential ablation (WACA) for pulmonary vein (PV) isolation (32 patients) or WACA alone (71 patients).

During the CONFIRM trial researchers aimed to evaluate:

• Whether AF is caused by localized electrical rotors or focal beats and whether these are visibleusing a computerized mapping system; and
• Whether localized ablation (FIRM) improved efficacy and terminated or slowed AF when added to conventional electrical isolation.

The primary endpoint of the trial was acute AF termination or slowing and AF freedom that was defined as AF less than 1 percent on implanted monitoring devices, according to the study's principal investigator Sanjiv Narayan, MD, PhD, of the University of California, San Diego and VA Medical Center.

Patients in both study arms had similar patient characteristics.

Narayan reported that acute AF termination or slowing occurred in 88 percent of patients in the FIRM-guided arm compared to 14 percent in the conventional arm. Additionally, he said that two-year data showed that 84.3 percent of patients in the FIRM-guided arm were free of AF compared with 50.5 percent in the conventional arm.

In the majority of patient cases sinus rhythm was achieved in 10 to 15 minutes, Narayan noted.

Additionally, Narayan reported that FIRM-alone terminated AF to sinus rhythm in six minutes (17 patients) and lengthened AF cycle length by more than 15 percent. Single procedure freedom from AF at one year was 25 percent higher for FIRM-WACA compared with WACA alone.

Rotor or focal drivers were seen in 97 percent of these AF patients (left appendage 79 percent; right appendage 21 percent).On average, two rotors were used in each patient, according to Narayan.

During a question and answer period, Karl-Heinz Kuck, MD, of the Asklepios Kilnik St. Georg in Hamburg, Germany, asked whether these rotors could be simultaneously recorded during a single episode.

Narayan offered that “with the new versions of the system we are able to see the sites in one swoop … then ablate them. We then re-induce AF, wait a specific time period of 15 minutes, and then target again.”

Narayan offered that this procedure can be repeated as many as three times; however, he said it would be rare that you would ever have to conduct the procedure this many times.

“The promising results of the CONFIRM study show that with a single procedure you can prove the success rate of conventional ablation,” Narayan concluded. “This has really changed how procedures are controlled in terms of time and in terms of outcomes.”

The trial was sponsored by the National Institutes of Health (NIH).