Introduction:
Targets for the ablation of atrial fibrillation (AF) are debated. In particular, recent studies questioning fractionated electrograms and lines has increased focus on AF substrates of rotors and focal impulses. These AF sources are seen in both atria, but have unknown etiology. We hypothesized that differential remodeling between the right atrium (RA), whose structural changes are largely undefined, and left atrium (LA) influence the distribution of AF sources and the outcomes from AF source ablation.
Methods:
In 60 patients at AF ablation (62±10 years, 60% persistent, 5% long-standing persistent), we compared size differences between RA and LA to the number of sources in each chamber and outcomes from AF source-guide ablation. We studied if a 64-pole basket differentially fit the LA or RA, judged by deformation of its splines by the atria (fig. A, B) over multiple cardiac cycles on fluoroscopy. Ablation targeted sources in both atria and was followed by PVI, with follow-up per guidelines.
Results:
Using baskets in both atria, 205 sources (LA 138; RA 67) were identified and ablated. Notably, the same basket in each patient was
dynamically
deformed by RA in 51 (85%) of cases but in the LA in only 39 (65%), indicating greater LA remodeling. The number of AF sources was higher in the presence of basket deformation of RA (n=174) than LA (n=130). LA deformation correlated with LVEF (p=0.05). Freedom from AF at 1 year was reduced in patients with no basket deformation (i.e. dilation) in LA (p=0.07) or RA (p=0.06). Notably, single procedure AF freedom was substantially lower in patients with differential remodeling (deformation in only 1 chamber) of 84% vs. 60% (fig C).
Conclusions:
Structural atrial remodeling influences the number of electrical rotors and focal sources in each chamber. A mismatch between right and left atrial remodeling predicts lower success from rotor ablation. These data also provide novel clinical indices of effective basket positioning.
Echocardiographic predictors of cardioembolic stroke due to underlying atrial fibrillation: Reliable left atrial remodeling signs in acute stroke
