Effect of scar and pacing location on repolarization in a porcine myocardial infarction model

TY - JOUR

T1 - Effect of scar and pacing location on repolarization in a porcine myocardial infarction model

AU - Elliott, Mark K.

AU - Costa, Caroline Mendonca

AU - Whitaker, John

AU - Gemmell, Philip

AU - Mehta, Vishal S.

AU - Sidhu, Baldeep S.

AU - Gould, Justin

AU - Williams, Steven E.

AU - O'Neill, Mark

AU - Razavi, Reza

AU - Niederer, Steven

AU - Bishop, Martin J.

AU - Rinaldi, Christopher A.

N1 - Publisher Copyright: © 2022 Heart Rhythm Society

PY - 2022/4

Y1 - 2022/4

N2 - Background: The effect of chronic ischemic scar on repolarization is unclear, with conflicting results from human and animal studies. An improved understanding of electrical remodeling within scar and border zone tissue may enhance substrate-guided ablation techniques for treatment of ventricular tachycardia. Computational modeling studies have suggested increased dispersion of repolarization during epicardial, but not endocardial, left ventricular pacing, in close proximity to scar. However, the effect of endocardial pacing near scar in vivo is unknown. Objective: The purpose of this study was to investigate the effect of scar and pacing location on local repolarization in a porcine myocardial infarction model. Methods: Six model pigs underwent late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) imaging followed by electroanatomic mapping of the left ventricular endocardium. LGE-CMR images were registered to the anatomic shell and scar defined by LGE. Activation recovery intervals (ARIs), a surrogate for action potential duration, and local ARI gradients were calculated from unipolar electrograms within areas of late gadolinium enhancement (aLGE) and healthy myocardium. Results: There was no significant difference between aLGE and healthy myocardium in mean ARI (304.20 ± 19.44 ms vs 300.59 ± 19.22 ms; P = .43), ARI heterogeneity (23.32 ± 11.43 ms vs 24.85 ± 12.99 ms; P = .54), or ARI gradients (6.18 ± 2.09 vs 5.66 ± 2.32 ms/mm; P = .39). Endocardial pacing distance from scar did not affect ARI gradients. Conclusion: Our findings suggest that changes in ARI are not an intrinsic property of surviving myocytes within scar, and endocardial pacing close to scar does not affect local repolarization.

AB - Background: The effect of chronic ischemic scar on repolarization is unclear, with conflicting results from human and animal studies. An improved understanding of electrical remodeling within scar and border zone tissue may enhance substrate-guided ablation techniques for treatment of ventricular tachycardia. Computational modeling studies have suggested increased dispersion of repolarization during epicardial, but not endocardial, left ventricular pacing, in close proximity to scar. However, the effect of endocardial pacing near scar in vivo is unknown. Objective: The purpose of this study was to investigate the effect of scar and pacing location on local repolarization in a porcine myocardial infarction model. Methods: Six model pigs underwent late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) imaging followed by electroanatomic mapping of the left ventricular endocardium. LGE-CMR images were registered to the anatomic shell and scar defined by LGE. Activation recovery intervals (ARIs), a surrogate for action potential duration, and local ARI gradients were calculated from unipolar electrograms within areas of late gadolinium enhancement (aLGE) and healthy myocardium. Results: There was no significant difference between aLGE and healthy myocardium in mean ARI (304.20 ± 19.44 ms vs 300.59 ± 19.22 ms; P = .43), ARI heterogeneity (23.32 ± 11.43 ms vs 24.85 ± 12.99 ms; P = .54), or ARI gradients (6.18 ± 2.09 vs 5.66 ± 2.32 ms/mm; P = .39). Endocardial pacing distance from scar did not affect ARI gradients. Conclusion: Our findings suggest that changes in ARI are not an intrinsic property of surviving myocytes within scar, and endocardial pacing close to scar does not affect local repolarization.

KW - Cardiac magnetic resonance imaging

KW - Electroanatomic mapping

KW - Myocardial scar

KW - Repolarization

KW - Ventricular arrhythmia

UR - http://www.scopus.com/inward/record.url?scp=85128147238&partnerID=8YFLogxK

U2 - 10.1016/j.hroo.2022.01.008

DO - 10.1016/j.hroo.2022.01.008

M3 - Article

AN - SCOPUS:85128147238

SN - 2666-5018

VL - 3

SP - 186

EP - 195

JO - Heart Rhythm O2

JF - Heart Rhythm O2

IS - 2

ER -