A late breaking trial presented at Heart Rhythm 2013 (8–11 May, Denver, USA) has demonstrated that targeted ablation of stable rotors and focal sources can eliminate paroxysmal atrial fibrillation without the need to isolate the pulmonary veins. Results of the PRECISE trial also showed that paroxysmal AF is sustained by stable rotors or focal sources revealed by Focal Impulse and Rotor Mapping (FIRM) in patient-specific bi-atrial locations
Data from the PRECISE (The precise rotor elimination without concomitant pulmonary vein isolation for subsequent elimination of paroxysmal atrial fibrillation) trial were presented by Sanjiv Narayan, University of California San Diego, San Diego, USA. He commented: “We set up this study to solve the quandary of why atrial fibrillation ablation is not as good as we wanted it to be and why it works well in some patients but not in others. If we look back over the past decade, different approaches have been proposed for atrial fibrillation ablation that do and do not involve isolating the pulmonary veins. Most studies report success after multiple procedures, but from a patient’s perspective the single procedure success is really important. If we look at pulmonary vein isolation studies in aggregate we see that the single procedure success rates are about 50%. We decided to look at this in detail.”
The CONFIRM (Conventional ablation for atrial fibrillation with or without focal impulse and rotor modulation) trial, whose results were presented by Narayan at Heart Rhythm 2011, looked at the idea that outside of the veins there are other driving areas of atrial fibrillation-rotors or focal sources-and that eliminating those would be beneficial.
Narayan explained, “In CONFIRM we showed that when you do that ablation, so-called rotor elimination or FIRM, you can raise the single-procedure success rate from about 50% in patients who had pulmonary vein isolation alone to about 80% in people who had rotor ablation as well. But CONFIRM did not address two important matters: it looked mostly at patients who had advanced disease, and persistent atrial fibrillation in particular, and did not address what would happen if you only eliminated the rotors and did not do pulmonary vein isolation.”
In PRECISE, 31 consecutive paroxysmal atrial fibrillation patients (mean age 59 years) who had not had a previous ablation were enrolled at five US centres. Atrial fibrillation was recorded with 64 pole basket catheters and mapped with RhythmView (Topera). The investigators found an average of 2.5 rotors or focal sources in each patient and ablated them. The average time for ablation was 20 minutes. Of the ablated sites, 34% were located in the right atrium. According to Narayan, “this was interesting as we typically do not go into the right atrium.”
The results showed that at a median follow-up of 223 days the single procedure success rate, of freedom from atrial fibrillation, was 82%. By comparison, in the CONFIRM trial, freedom from atrial fibrillation after pulmonary vein isolation in paroxysmal atrial fibrillation patients was 45%.
Narayan concluded that these results showed that, in patients with paroxysmal atrial fibrillation, the elimination of stable rotors and focal sources can be very successful eliminating symptomatic and asymptomatic atrial fibrillation without the need for pulmonary vein isolation. He said that limitations of the study include the fact that current mapping baskets are suboptimal so that results may improve with better designs, and that PRECISE is a single-arm study. “Larger patient numbers and longer follow-up are required, as well as additional studies including patients with persistent atrial fibrillation,” he said.