Abstract 11104: Rapid Termination of Human Atrial Fibrillation by Ablation At Localized Sources: Focal Impulse and Rotor Modulation (FIRM)
Introduction: In animal studies, atrial fibrillation (AF) may be sustained by localized electrical rotors or repetitive focal beats. Very recent studies have shown that localized electrical rotors and focal beats also exist in human AF. We applied novel physiological mapping to test the hypothesis that focal impulse and rotor modulation (FIRM) by targeted ablation would acutely terminate or slow human AF.
Methods: In 34 AF patients (62±9 years; left atrial, LA size 48±7 mm; 23 persistent), we recorded AF from 64 pole basket catheters (Boston Scientific) in LA and RA. We applied the Hilbert transform biatrially to identify and visualize localized sources for AF. Limited ablation at rotors and focal impulses (FIRM) was performed first, followed by conventional ablation including PV isolation.
Results: Patient-specific FIRM maps revealed rotors and focal impulses in 100% of patients, each with 2.2±0.9 rotors (n=48) or focal impulses (n=22). FIRM (with no other ablation) terminated AF in n=21 patients at 6.4±5.3 minutes, to sinus rhythm (n=17), typical flutter (n=2), mitral flutter (n=1) and focal tachycardia (n=1). In n=9 patients, FIRM slowed AF by 28±10 ms (17±4%). Fig A shows, in a man with longstanding AF, multiple prior cardioversions and no prior ablations, a rotor (continuous counterclockwise activation) in the low LA (fig B) with fibrillatory conduction to remaining LA and the RA. FIRM (localized ablation at the rotor only) terminated AF to sinus rhythm within 1 minute (fig C). The patient is AF-free on implanted loop monitor.
Conclusions: Physiological imaging reveals rotors and focal impulses in human AF, where limited ablation (FIRM) rapidly terminated or substantially slowed AF in 89% of patients with persistent and paroxysmal AF. These results strongly support the localized-source hypothesis of human AF. How best to apply FIRM to reduce procedural time and to improve outcome from AF ablation remains to be determined.
- © 2011 by American Heart Association, Inc.