Endocardial unipolar voltage mapping to identify epicardial substrate in arrhythmogenic right ventricular cardiomyopathy/dysplasia

doi:10.1016/j.hrthm.2010.09.088

Heart Rhythm

Volume 8, Issue 1, January 2011, Pages 76-83

https://doi.org/10.1016/j.hrthm.2010.09.088 Get rights and content

Background

The risk and success of epicardial substrate ablation for ventricular tachycardia (VT) support the value of techniques identifying the epicardial substrate with endocardial mapping.

Objective

The purpose of this study was to test the hypothesis that endocardial unipolar voltage mapping in patients with right ventricular (RV) VT and preserved endocardial bipolar voltage abnormalities might identify the extent of epicardial bipolar voltage abnormality.

Methods

Using a cutoff of <5.5 mV for normal endocardial unipolar voltage derived from 8 control patients without structural heart disease, 10 patients with known ARVC/D (group 1, retrospective) and 13 patients with RV VT (group 2, prospective) with modest or no endocardial bipolar voltage abnormalities underwent detailed endocardial and epicardial mapping.

Results

The area of epicardial unipolar voltage abnormality in all 10 group 1 patients with ARVC/D (62 ± 21 cm²) and in 9 of the 13 group 2 patients (8 with criteria for ARVC/D) (53 ± 21 cm²) was on average three times more extensive than the endocardial bipolar abnormality and correlated (r = 0.63, P <.05 and r = 0.81, P <.008, respectively) with the larger area epicardial bipolar abnormality with respect to size (group 1: 82 ± 22 cm²; group 2: 68 ± 41 cm²) and location. In the remaining 4 group 2 patients and 3 additional reference patients without structural heart disease, endocardial bipolar, endocardial unipolar, and, as predicted, epicardial bipolar voltage all were normal.

Conclusion

Endocardial unipolar mapping with cutoff of 5.5 mV identifies more extensive areas of epicardial bipolar signal abnormalities in patients with ARVC/D and limited endocardial VT substrate.

Introduction

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is characterized by loss of cardiomyocytes with replacement by fibrofatty tissue.¹ The pathologic process involves primarily the right ventricle (RV), resulting in ventricular tachycardia (VT) and RV dysfunction. Histopathologic studies have demonstrated an epicardial predominance of the fibrofatty tissue, suggesting that the disease process typically begins in the epicardium and progresses toward the endocardium.2, 3, 4, 5

Although the definitions of the typical perivalvular electroanatomic voltage abnormalities and irrigated catheters have improved the efficacy of endocardial VT catheter ablation in ARVC/D patients, success has not been uniformly achieved.6, 7, 8, 9 We recently described the use of a combined endocardial/epicardial substrate-based ablation approach to facilitate arrhythmia control in the setting of drug-refractory VT and previous failed endocardial ablation in an ARVC/D patient population.¹⁰ A characteristic finding in these select patients was the marked degree of bipolar electrogram abnormalities exhibited on the RV epicardial surface relative to the endocardial surface. A substrate-based ablation approach relying on the endocardium alone would underestimate the substrate burden. Thus, it becomes imperative to identify the presence of a more extensive epicardial substrate and the need for epicardial access, mapping, and ablation. The purpose of this study was to determine whether endocardial unipolar voltage mapping, which should provide a more global assessment of myocardial voltage, predicts the extent of epicardial substrate abnormalities in ARVC/D patients and in other RV VT patients with no or limited endocardial bipolar voltage abnormalities.

Section snippets

Defining normal RV endocardial unipolar electrograms

To establish a reference value for normal unipolar electrograms, we performed detailed RV endocardial sinus rhythm mapping in eight patients (6 men and 2 women, mean age 36 ± 18 years) without structural heart disease undergoing electrophysiologic evaluation after obtaining informed consent in accordance with the institutional guidelines of the University of Pennsylvania Health System. None of the eight reference patients were taking cardioactive drugs, and all had normal echocardiograms. All

Normal unipolar electrogram

From 105 to 164 endocardial RV electrograms were recorded per patient in the eight reference patients. Ninety-five percent of unipolar signals had an amplitude >5.5 mV and defined a normal unipolar electrogram amplitude. Dense scar for display purposes was arbitrarily defined as having a unipolar signal amplitude <3.5 mV.

Group 1: Retrospective analysis

Thirteen consecutive patients presenting with ARVC/D and documented VT underwent simultaneous endocardial and epicardial mapping. Three of the 13 patients had a significant

Discussion

In this study, we found that among ARVC/D patients with only modest (0%–42%) endocardial disease involvement as measured by endocardial bipolar voltage mapping, the degree of epicardial involvement was dramatically greater, thus confirming our prior observations. Moreover, endocardial unipolar voltage mapping defined the presence of and more closely approximated the greater extent of epicardial bipolar signal abnormalities that serve as a substrate for VT in the setting of ARVC/D.

Conclusion

This study describes a new technique for identifying the presence and anatomic extent of anticipated epicardial bipolar voltage abnormalities consistent with “scar” in patients with ARVC/D. The study defined normal unipolar RV endocardial signal as having an amplitude >5.5 mV and validated the use of endocardial unipolar voltage mapping to identify confluent areas of signals with an amplitude <5.5 mV as a strategy for approximating the degree and location of epicardial bipolar voltage

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Myocardial scar in ischemic cardiomyopathy is predominantly endocardial, however, between 5% and 15% of these patients have an arrhythmogenic epicardial substrate. Percutaneous epicardial ablation should be considered in patients with ICM and VT especially if they failed an endocardial ablation. Simultaneous epicardial and endocardial ablation of VT in ICM may reduce short- and medium-term VT recurrence compared with an endocardial only approach. Cardiac imaging could be used to help guide patient selection for a combined epi-endo approach. Complications related to epicardial access can happen in up to 7% of patients. Epicardial ablation in these patients should be referred to experienced tertiary centers. We review the literature and share interesting cases.
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Three-dimensional electroanatomical mapping (EAM) can be helpful to diagnose arrhythmogenic right ventricular cardiomyopathy (ARVC). Yet, previous studies utilizing EAM have not systematically used contact-force sensing catheters (CFSC) to characterize the substrate in ARVC, which is the current gold standard to assure adequate tissue contact.
To investigate reference values for endocardial right ventricular (RV) EAM as well as substrate characterization in patients with ARVC by using CFSC.
Endocardial RV EAM during sinus rhythm was performed with CFSC in 12 patients with definite ARVC and 5 matched controls without structural heart disease. A subanalysis for the RV outflow tract (RVOT), septum, free-wall, subtricuspid region, and apex was performed. Endocardial bipolar and unipolar voltage amplitudes (BVA, UVA), signal characteristics and duration as well as the impact of catheter orientation on endocardial signals were also investigated.
ARVC patients showed lower BVA vs. controls (p = 0.018), particularly in the subtricuspid region (1.4, IQR:0.5–3.1 vs. 3.8, IQR:2.5-5 mV, p = 0.037) and RV apex (2.5, IQR:1.5–4 vs. 4.3,IQR:2.9–6.1 mV, p = 0.019). BVA in all RV regions yielded a high sensitivity and specificity for ARVC diagnosis (AUC 59–78%, p < 0.05 for all), with the highest performance for the subtricuspid region (AUC 78%, 95% CI:0.75–0.81, p < 0.001, negative predictive value 100%). A positive correlation between BVA and an orthogonal catheter orientation (46°-90°:r = 0.106, p < 0.001), and a negative correlation between BVA and EGM duration (r = −0.370, p < 0.001) was found.
EAM using CFSC validates previous bipolar cut-off values for normal endocardial RV voltage amplitudes. RV voltages are generally lower in ARVC as compared to controls, with the subtricuspid area being commonly affected and having the highest discriminatory power to differentiate between ARVC and healthy controls. Therefore, EAM using CFSC constitutes a promising tool for diagnosis of ARVC.
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There is a paucity of data describing mortality after catheter ablation of ventricular tachycardia (VT).
We describe the causes and predictors of cardiac transplant and/or mortality following catheter ablation of structural heart disease (SHD) related VT.
Over 10-years, 175 SHD patients underwent VT ablation. Clinical characteristics, and outcomes, were compared between patients undergoing transplant and/or dying and those surviving.
During 2.8 (IQR 1.9–5.0) years follow-up, 37/175 (21%) patients underwent transplant and/or died following VT ablation. Prior to ablation, these patients were older (70.3 ± 11.1 vs. 62.1 ± 13.9 years, P = 0.001), had lower left ventricular ejection fraction ([LVEF] 30 ± 12% vs. 44 ± 14%, P < 0.001), and were more likely to have failed amiodarone (57% vs. 39%, P = 0.050), compared to those that survived. Predictors of transplant and/or mortality included LVEF≤35% (HR 4.71 [95% CI 2.18–10.18], P < 0.001), age ≥ 65 years (HR 2.18 [95% CI 1.01–4.73], P = 0.047), renal impairment (HR 3.73 [95% CI 1.80–7.74], P < 0.001), amiodarone failure (HR 2.67 [95% CI 1.27–5.63], P = 0.010) and malignancy (HR 3.09 [95% CI 1.03–9.26], P = 0.043). Ventricular arrhythmia free survival at 6-months was lower in the transplant and/or deceased, compared to non-deceased group (62% vs. 78%, P = 0.010), but was not independently associated with transplant and/or mortality. The risk score, MORTALITIES-VA, accurately predicted transplant and/or mortality (AUC: 0.872 [95% CI 0.810–0.934]).
Cardiac transplant and/or mortality after VT ablation occurred in 21% of patients. Independent predictors included LVEF≤35%, age ≥ 65 years, renal impairment, malignancy, and amiodarone failure. The MORTALITIES-VA score may identify patients at high-risk of transplant and/or dying after VT ablation.
Electroanatomic mapping in athletes: Why and when. An expert opinion paper from the Italian Society of Sports Cardiology
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Three-dimensional electroanatomical mapping (EAM) has the potential to identify the pathological substrate underlying ventricular arrhythmias (VAs) in different clinical settings by detecting myocardial areas with abnormally low voltages, which reflect the presence of different cardiomyopathic substrates. In athletes, the added value of EAM may be to enhance the efficacy of third-level diagnostic tests and cardiac magnetic resonance (CMR) in detecting concealed arrhythmogenic cardiomyopathies. Additional benefits of EAM in the athlete include the potential impact on disease risk stratification and the consequent implications for eligibility to competitive sports. This opinion paper of the Italian Society of Sports Cardiology aims to guide general sports medicine physicians and cardiologists on the clinical decision when to eventually perform an EAM study in the athlete, highlighting strengths and weaknesses for each cardiovascular disease at risk of sudden cardiac death during sport. The importance of early (preclinical) diagnosis to prevent the negative effects of exercise on phenotypic expression, disease progression, and worsening of the arrhythmogenic substrate is also addressed.
Adverse Prognosis of Patients With Septal Substrate After VT Ablation Due to Electrical Storm
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Data about ventricular tachycardia (VT) ablation in patients with electrical storm (ES) is limited.
This study sought to compare the prognostic outcome of patients undergoing VT ablation after ES with and without a septal substrate.
In this large single-center study, consecutive patients presenting with ES and undergoing VT ablation from June 2018 to April 2021 were included. Patients with septal substrate were compared with patients without septal substrate regarding endpoints of cardiovascular mortality, VT recurrences, recurrences of the clinical VT, and rehospitalization rates.
A total of 107 patients undergoing a first VT ablation because of electrical storm (ES) were included (age 65 ± 13 years, 86% male, 45% ischemic cardiomyopathy). Major complications occurred in 11% of all patients with increased postinterventional third-degree atrioventricular blocks among patients with septal substrate (9% vs 0%; P = 0.063). Partial ablation successes were similar (95% with a septal substrate vs 100% without a septal substrate; P = 0.251). Complete ablation success was achieved in 63% with a septal substrate and in 87% without a septal substrate (P = 0.004). After a median 22 months of follow-up, patients with septal substrate died significantly more often from cardiovascular causes (26% vs 7%; log-rank P = 0.018). In univariate analysis cardiovascular mortality for ES patients with septal substrate was 4.1-fold higher (HR: 4.192; CI: 1.194-14.719; P = 0.025). Independent predictors of adverse outcome in multivariable regression analysis were presence of septal substrate (HR: 5.723; P = 0.025) and increased age (HR: 1.104; P = 0.003). Recurrences of any ventricular arrhythmia (67% vs 56%; log rank P = 0.554) and rehospitalization rates (80% vs 66%; log rank P = 0.515) were similar between groups. Recurrences of clinical VT were similar (7% vs 2%; P = 0.252).
Presence of a septal substrate is associated with adverse long-term cardiovascular mortality in patients admitted for VT ablation after ES. Despite decreased acute ablation successes in these patients, VT recurrence rates were similar to those without a septal substrate during follow-up.

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: Drs. Marchlinski, Callans, and Hutchinson have received research support from Biosense Webster unrelated to the content of this manuscript. Dr. Haqqani is the recipient of an Overseas Training Fellowship (544309) from the National Health and Medical Research Council of Australia and the Bayer Fellowship from the Royal Australasian College of Physicians.

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ClinicalImaging/mappingEndocardial unipolar voltage mapping to identify epicardial substrate in arrhythmogenic right ventricular cardiomyopathy/dysplasia

Background

Objective

Methods

Results

Conclusion

Introduction

Section snippets

Defining normal RV endocardial unipolar electrograms

Normal unipolar electrogram

Group 1: Retrospective analysis

Discussion

Conclusion

Heart Rhythm

J Am Coll Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

Heart Rhythm

J Am Coll Cardiol

J Am Coll Cardiol

Circulation

Arrhythmogenic right ventricular cardiomyopathy and fatty replacement of the right ventricular myocardium: are they different diseases?

Circulation

Clinical
Imaging/mapping
Endocardial unipolar voltage mapping to identify epicardial substrate in arrhythmogenic right ventricular cardiomyopathy/dysplasia