Evaluation of the reentry vulnerability index to predict ventricular tachycardia circuits using high-density contact mapping

Michele Orini,Pier D Lambiase,Simon Sporton,Jaswinder Gill,Nicholas Child,Anthony Chow,Peter Taggart,Bradley Porter,Malcolm Finlay,Mark J Earley,Mehul Dhinoja,Richard J Schilling,Ross J Hunter,Fernanda Campos ,Christopher Aldo Rinaldi ,Ben Hanson ,Martin Löwe ,Neil Srinivasan ,Martin J Bishop ,Aaron Graham

doi:10.1016/j.hrthm.2019.11.013

Abstract

BackgroundIdentifying arrhythmogenic sites to improve ventricular tachycardia (VT) ablation outcomes remains unresolved. The reentry vulnerability index (RVI) combines activation and repolarization timings to identify sites critical for reentrant arrhythmia initiation without inducing VT.ObjectiveThe purpose of this study was to provide the first assessment of RVI’s capability to identify VT sites of origin using high-density contact mapping and comparison with other activation-repolarization markers of functional substrate.MethodsEighteen VT ablation patients (16 male; 72% ischemic) were studied. Unipolar electrograms were recorded during ventricular pacing and analyzed offline. Activation time (AT), activation–recovery interval (ARI), and repolarization time (RT) were measured. Vulnerability to reentry was mapped based on RVI and spatial distribution of AT, ARI, and RT. The distance from sites identified as vulnerable to reentry to the VT site of origin was measured, with distances <10 mm and >20 mm indicating accurate and inaccurate localization, respectively.ResultsThe origins of 18 VTs (6 entrainment, 12 pace-mapping) were identified. RVI maps included 1012 (408–2098) (median, 1st–3rd quartiles) points per patient. RVI accurately localized 72.2% VT sites of origin, with median distance of 5.1 (3.2–10.1) mm. Inaccurate localization was significantly less frequent for RVI than AT (5.6% vs 33.3%; odds ratio 0.12; P = .035). Compared to RVI, distance to VT sites of origin was significantly larger for sites showing prolonged RT and ARI and were nonsignificantly larger for sites showing highest AT and ARI gradients.ConclusionRVI identifies vulnerable regions closest to VT sites of origin. Activation-repolarization metrics may improve VT substrate delineation and inform novel ablation strategies.

Highlights

Recurrence rates of ventricular tachycardia (VT) in structural heart disease remain suboptimal, with 50% on average for a first-time catheter ablation highlighting the need for more effective ablation strategies.[1]
Compared to reentry vulnerability index (RVI), distance to VT sites of origin was significantly larger for sites showing prolonged repolarization time (RT) and activation– recovery interval (ARI) and were nonsignificantly larger for sites showing highest Activation time (AT) and ARI gradients
The ability to reenter the proximal region depends on the conduction delay around the blocked area and on the timing of the returning wavefront relative to completion of repolarization and reexcitability in the proximal region.[6]. This is the basis of the reentry vulnerability index (RVI),[6,7] an activationrepolarization metric that provides a point-by-point quantification of the likelihood of reentry and enables functional VT substrate delineation

Summary

Introduction

Recurrence rates of ventricular tachycardia (VT) in structural heart disease remain suboptimal, with 50% on average for a first-time catheter ablation highlighting the need for more effective ablation strategies.[1]. A prerequisite for reentry is unidirectional block whereby an activation wavefront blocks at a region of late repolarization where tissue is still refractory circumvents the area of block through slow conducting pathways and reenters the proximal region. The ability to reenter the proximal region depends on the conduction delay around the blocked area and on the timing of the returning wavefront relative to completion of repolarization and reexcitability in the proximal region.[6] This is the basis of the reentry vulnerability index (RVI),[6,7] an activationrepolarization metric that provides a point-by-point quantification of the likelihood of reentry and enables functional VT substrate delineation. The reentry vulnerability index (RVI) combines activation and repolarization timings to identify sites critical for reentrant arrhythmia initiation without inducing VT

Methods

Results

Discussion

Conclusion