Abstract
Pulmonary vein isolation (PVI) with radiofrequency ablation (RFA) is the cornerstone of atrial fibrillation (AF) therapy, but few strategies exist for when it fails. To guide RFA, phase singularity (PS) mapping locates reentrant electrical waves (rotors) that perpetuate AF. The goal of this study was to test existing and develop new RFA strategies for terminating rotors identified with PS mapping. It is unsafe to test experimental RFA strategies in patients, so they were evaluated in silico using a bilayer computer model of the human atria with persistent AF (pAF) electrical (ionic) and structural (fibrosis) remodeling. pAF was initiated by rapidly pacing the right (RSPV) and left (LSPV) superior pulmonary veins during sinus rhythm, and rotor dynamics quantified by PS analysis. Three RFA strategies were studied: (i) PVI, roof, and mitral lines; (ii) circles, perforated circles, lines, and crosses 0.5–1.5 cm in diameter/length administered near rotor locations/pathways identified by PS mapping; and (iii) 4–8 lines streamlining the sequence of electrical activation during sinus rhythm. As in pAF patients, 2 ± 1 rotors with cycle length 185 ± 4 ms and short PS duration 452 ± 401 ms perpetuated simulated pAF. Spatially, PS density had weak to moderate positive correlations with fibrosis density (RSPV: r = 0.38, p = 0.35, LSPV: r = 0.77, p = 0.02). RFA PVI, mitral, and roof lines failed to terminate pAF, but RFA perforated circles and lines 1.5 cm in diameter/length terminated meandering rotors from RSPV pacing when placed at locations with high PS density. Similarly, RFA circles, perforated circles, and crosses 1.5 cm in diameter/length terminated stationary rotors from LSPV pacing. The most effective strategy for terminating pAF was to streamline the sequence of activation during sinus rhythm with >4 RFA lines. These results demonstrate that co-localizing 1.5 cm RFA lesions with locations of high PS density is a promising strategy for terminating pAF rotors. For patients immune to PVI, roof, mitral, and PS guided RFA strategies, streamlining patient-specific activation sequences during sinus rhythm is a robust but challenging alternative.
Highlights
Atrial fibrillation (AF) is a worldwide epidemic that decreases the quality of life and increases mortality in its victims (Go et al, 2001)
It was determined that radiofrequency ablation (RFA) with Pulmonary vein isolation (PVI), roof, and mitral lines failed to terminate persistent AF (pAF) rotors far from the pulmonary vein (PV), and likewise for small RFA lesions placed at Left Atrium (LA) locations not intersecting pAF rotor pathways
The results from this study support the hypotheses that small RFA lesions guided by phase singularity (PS) maps is a safe and effective pAF therapy, and that streamlining activation sequences during sinus rhythm with continuous RFA lines is an alternative pAF termination approach when all else fails
Summary
Atrial fibrillation (AF) is a worldwide epidemic that decreases the quality of life and increases mortality in its victims (Go et al, 2001). From theoretical AF studies (Lewis, 1924; Allessie et al, 1977), to animal AF models (Davidenko et al, 1990; Gray et al, 1998), to AF patients (Narayan et al, 2012; Haïssaguerre et al, 2014), AF is driven by high-frequency electrical activity that prevents the synchronized muscular contractions of the left (LA) and right (RA) atrium The mechanism for this fibrillatory behavior can be explained by either focal impulse generation leading to the collision of multiple wavelets (Moe and Abildskov, 1959), or via spiraling reentrant waves with peripheral wave breakup (Davidenko et al, 1990). Without spatial knowledge on the electrical behavior of pAF rotors in patients prior to RFA procedures, terminating pAF can be extremely challenging with long procedure times and excessive tissue damage from the many unguided RFA lesions administered to extinguish all rotors (O’Neill et al, 2009)
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