Abstract 11131: Migration Loci of Rotors for Human Atrial Fibrillation Define Ablation Targets for Focal Impulse and Rotor Modulation (FIRM)
Introduction: Atrial fibrillation (AF) in animals may be caused by localized sources (electrical rotors or focal beats), which may be stable but typically migrate. This has implications for the ablation of localized sources in human AF, that have recently been demonstrated. We hypothesized that human AF rotors migrate within a constrained region (locus) that may define an AF ablation target.
Methods: In 26 patients prior to AF ablation (63±10 years; 16 persistent), we recorded AF with monophasic action potentials (MAP) and 64 pole basket catheters in both atria. Signals were detrended and noise-filtered, then MAP restitution and the Hilbert Transform were applied. Rotor cores, identified at crossing points of real/imaginary components of the Hilbert transform, were tracked over time to define migration loci. Targeted ablation (Focal Impulse and Rotor Modulation, FIRM) was applied at migration loci first, followed by conventional ablation.
Results: All patients exhibited localized AF sources (mean 2.1±0.7) with n=36 rotors and n=19 focal beats. Each source controled AF cycle length (p<0.01) and migrated. Notably, migration loci were constrained in persistent (2.5±1.5 cm2) and paroxysmal (2.2±1.0 cm2; p=NS) AF. FIRM ablation at these loci terminated or substantially slowed AF in 24/26 patients. Fig A shows a left atrial rotor (color-coded counterclockwise activation around a core) in persistent AF. Fig B shows constrained and reproducible rotor core migration over time (color coded; 3.2 cm2). FIRM ablation over this locus (fig C) terminated AF to sinus rhythm in 1 minute. The patient is AF-free on implanted loop monitor at 6 months.
Conclusions: Electrical rotors and/or repetitive focal impulses, that drive fibrillatory activity in human AF, migrate within remarkably constrained spatial loci over time. FIRM ablation directly over these loci terminated or slowed AF in 92% of patients with persistent and paroxysmal AF.
- © 2011 by American Heart Association, Inc.