Prolonged action potential duration and dynamic transmural action potential duration heterogeneity underlie vulnerability to ventricular tachycardia in patients undergoing ventricular tachycardia ablation.

Neil T Srinivasan,Anthony W Chow,Pier D Lambiase,Michele Orini,Ross J Hunter,Mehul B Dhinoja,Rui Providencia,Syed Y Ahsan,Richard J Schilling,Peter Taggart,Martin D Lowe

doi:10.1093/europace/euy260

Neil T Srinivasan, Anthony W Chow + Show 9 more

Open Access

https://doi.org/10.1093/europace/euy260

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Journal: Europace	Publication Date: Nov 29, 2018
Citations: 19	License type: CC BY 4.0

Affiliation: University College London, St Bartholomew's Hospital

Abstract

AimsDifferences of action potential duration (APD) in regions of myocardial scar and their borderzones are poorly defined in the intact human heart. Heterogeneities in APD may play an important role in the generation of ventricular tachycardia (VT) by creating regions of functional block. We aimed to investigate the transmural and planar differences of APD in patients admitted for VT ablation.Methods and resultsSix patients (median age 53 years, five male); (median ejection fraction 35%), were studied. Endocardial (Endo) and epicardial (Epi) 3D electroanatomic mapping was performed. A bipolar voltage of <0.5 mV was defined as dense scar, 0.5–1.5 mV as scar borderzone, and >1.5 mV as normal. Decapolar catheters were positioned transmurally across the scar borderzone to assess differences of APD and repolarization time (RT) during restitution pacing from Endo and Epi. Epi APD was 173 ms in normal tissue vs. 187 ms at scar borderzone and 210 ms in dense scar (P < 0.001). Endocardial APD was 210 ms in normal tissue vs. 222 ms in the scar borderzone and 238 ms in dense scar (P < 0.01). This resulted in significant transmural RT dispersion (ΔRT 22 ms across dense transmural scar vs. 5 ms in normal transmural tissue, P < 0.001), dependent on the scar characteristics in the Endo and Epi, and the pacing site.ConclusionAreas of myocardial scar have prolonged APD compared with normal tissue. Heterogeneity of regional transmural and planar APD result in localized dispersion of repolarization, which may play an important role in initiating VT.

Highlights

Ventricular tachycardia (VT) is an important cause of defibrillator therapy and cardiac death
Decapolar catheters were placed across the Epi scar region traversing regions of dense scar, scar borderzone and healthy tissue, and poles were paired for comparison with a transmural geometrically opposed decapolar catheter in the endocardium over normal bipolar voltage (Figure 1A)
The main findings are (i) areas of myocardial scar, regardless of pathology, have prolonged Activation recovery interval (ARI) compared with normal voltage tissue, (ii) the presence of scar decreases the ARI transmural gradient, the extent of which is dependent on the Endo and Epi scar characteristics, and (iii) alterations in transmural ARI gradient result in localized transmural dispersion of repolarization (DOR), dependent on the scar pattern and the activation sequence, which may play an important role in arrhythmogenesis

Summary

Introduction

Ventricular tachycardia (VT) is an important cause of defibrillator therapy and cardiac death. Of surviving tissue serve as sites of slow conduction and conduction block creating the necessary conditions for re-entry. The scar borderzone is an important substrate for VT, with several studies[1,2] demonstrating the efficacy of catheter ablation of this region. It is likely that the VT wavefront is heterogeneous, involving epicardial (Epi) loops[2] or isthmuses, as well as taking a complex 3D path involving the endocardium, mid-myocardium, and the epicardium.[3]

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