Mechanistic Comparison of "Nearly Missed" Versus "On-Target" Rotor Ablation

Masatoshi Yamazaki; Uma Mahesh R Avula; Omer Berenfeld; Jérôme Kalifa

doi:10.1016/j.jacep.2015.04.015

Mechanistic Comparison of "Nearly Missed" Versus "On-Target" Rotor Ablation

JACC Clin Electrophysiol. 2015 Aug;1(4):256-269. doi: 10.1016/j.jacep.2015.04.015. Epub 2015 Jun 22.

Authors

Masatoshi Yamazaki¹, Uma Mahesh R Avula², Omer Berenfeld², Jérôme Kalifa³

Affiliations

¹ Center for Arrhythmia Research, Cardiovascular Research Center, Department of Internal Medicine, Division of Cardiology, University of Michigan, Ann Arbor, Michigan; Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan.
² Center for Arrhythmia Research, Cardiovascular Research Center, Department of Internal Medicine, Division of Cardiology, University of Michigan, Ann Arbor, Michigan.
³ Center for Arrhythmia Research, Cardiovascular Research Center, Department of Internal Medicine, Division of Cardiology, University of Michigan, Ann Arbor, Michigan. Electronic address: kalifaj@umich.edu.

PMID: 29759314
DOI: 10.1016/j.jacep.2015.04.015

Abstract

Objectives: This study used advanced optical mapping techniques to examine atrial fibrillation (AF) dynamics before and after 2 distinct electrogram-based ablation strategies: complex fractionated atrial electrograms (CFAEs) and DFmax/rotor ablation.

Background: Among the electrogram analytical features proposed to unravel the atrial regions that perpetuate AF, CFAEs, highest dominant frequency sites (DFmax), and, more recently, phase analysis-enabled rotor mapping have received the largest attention. Still, the mechanisms by which these approaches modulate AF dynamics and lead to AF termination are unknown.

Methods: In Langendorff-perfused sheep hearts, AF was maintained by the continuous perfusion of acetylcholine and high-resolution endocardial-epicardial optical videos were recorded from the left atrial free wall and the posterior left atrium. Then, DFmax/rotor regions (n = 7), or CFAE regions harboring the highest wavebreak density (HWD) (n = 5), were targeted with a 4F ablation catheter (5 to 15 W, 30 to 60 s/point). Thereafter, we examined the changes in AF dynamics and whether AF terminated.

Results: DFmax/rotor point ablation resulted in a significant decrease in DFmax values. In 2 animals AF terminated, whereas in the remaining 5 animals the post-ablation DFmax domain remained in the vicinity of its pre-ablation location. However, after HWD/CFAEs density ablation, DFmax values did not change, AF did not terminate, and post-ablation DFmax domains relocated from the left atrial free wall to the pulmonary vein-posterior left atrium region. In another group of hearts (n = 12), we observed that upon a progressive increase in acetylcholine concentration-mimicking the acute electrophysiological changes occurring after ablation-3-dimensional rotors drifted from one atrial region to another along large gradients of myocardial thickness.

Conclusions: "On-target" DFmax/rotor ablation leads to the annihilation of the fibrillation-driving rotor. This translates into large decreases in AF frequency or AF termination. In contrast, "nearly missed" HWD/CFAEs ablation spares the fibrillation-driving rotor, and set the stage for rotor drift along large myocardial thickness gradients.

Keywords: ablation; atrial fibrillation; cholinergic stimulation; scroll wave.