Elsevier

Heart Rhythm

Volume 20, Issue 6, June 2023, Pages 844-852
Heart Rhythm

Clinical
Ablation
Sinus rhythm electrocardiographic abnormalities, sites of origin, and ablation outcomes of ventricular premature depolarizations initiating ventricular fibrillation

https://doi.org/10.1016/j.hrthm.2023.03.019Get rights and content

Abstract

Background

Ventricular fibrillation (VF) can be initiated by ventricular premature depolarizations (VPDs) in the absence of obvious structural abnormalities.

Objective

The purpose of this study was to determine the prevalence of 12-lead electrocardiographic (ECG) sinus rhythm reduced QRS amplitude, QRS fractionation (QRSf), and early repolarization (ER) pattern, and the outcome of catheter ablation and VPD anatomic distribution in patients with VPDs initiating VF.

Methods

We compared a cohort with no apparent structural heart disease and VPDs initiating VF (group 1; n = 42) to a reference cohort (group 2; n = 61) of patients with no structural heart disease and symptomatic unifocal VPDs.

Results

A reduced QRS amplitude (<0.55 mV) in aVF (59% vs 10%; P <.001), QRSf in ≥2 contiguous leads (50% vs 16%; P <.001), and ER pattern (21.4% vs 1.6%; P = .01) were more common in group 1 than in group 2. At least 1 abnormal ECG finding was present in 34 group 1 patients (81%) vs 17 group 2 patients (28%) (P <.001). VPD origin included right ventricular and left ventricular distal Purkinje system and moderator band/papillary muscles in 83% of group 1 patients vs 18% of group 2 patients (P <.001). VF was eliminated with a single ablation procedure in 77% of group 1 patients with at least 2 years of follow-up.

Conclusion

A reduced QRS amplitude (<0.55 mV) in aVF, QRSf in ≥2 contiguous leads, and/or an ER pattern are frequently observed in patients with VPDs initiating VF. VPDs initiating VF typically originate from the distal Purkinje system and papillary muscles and can be successfully eliminated with catheter ablation.

Introduction

Ventricular fibrillation (VF) can be initiated by ventricular premature depolarizations (VPDs) in the absence of gross cardiac structural abnormalites.1,2 The distal Purkinje network, particularly within papillary muscles (PAPs), seems to be a common source of these VPDs initiating “idiopathic” VF.1,3, 4, 5

Clinical evidence supports an association between the electrocardiographic (ECG) pattern of early repolarization (ER), inferior epicardial substrate with abnormal electrograms (EGMs) in some patients, and VF.6 However, there are limited data describing 12-lead ECG sinus rhythm depolarization abnormalities such as QRS fractionation (QRSf) and reduced QRS amplitude in patients with VPDs initiating VF.

We sought to evaluate the prevalence and distribution of sinus rhythm ECG abnormalities reflected on the 12-lead ECG as reduced QRS amplitude, QRSf, and the presence of an ER pattern and to describe the observations made during, and the outcome of, catheter ablation of VPDs initiating VF.

Section snippets

Study population

We retrospectively analyzed data of 4560 patients who underwent catheter ablation for ventricular arrhythmias at the Hospital of the University of Pennsylvania. Between May 2007 and January 2022, 42 patients (0.9%) presented with VPDs initiating VF (group 1). Metabolic and toxicologic etiologies were excluded, and no structural or electrical causes were identified after extensive clinical investigation. Patients with apparently normal hearts were defined by normal 2-dimensional echocardiography

Study population clinical characteristics

Between May 2007 and January 2022, 42 patients with apparent structurally normal heart underwent catheter ablation of VPDs initiating VF (group 1). Of these 42 patients, 31 (74%) presented with sudden cardiac arrest and only 5 (11%) had a family history of SCD. Of the remaining 11 patients (26%), 10 presented with syncope and 1 with documentation of episodes of nonsustained PMVT with no symptoms. Fourteen patients underwent genetic testing. Of these patients, 5 (35%) demonstrated a variant of

Acute and long-term outcome of catheter ablation for VF triggers

In 29 of 40 patients (72.5%) in group 1, VPDs occurred in sufficient number to be targeted based on activation and pacemapping, with a goal of eliminating at least> 80% of VPDs. At the end of the first procedure, VPDs were completely abolished (16 patients) or at least >80% reduced from baseline (12 patients) in 28 of these 29 patients (96.6%) in group 1. In 11 patients (27.5%) in group 1, VPDs were not elicited or were rare during EP study, and an ablation strategy based on only pacemapping

Discussion

This is the first study describing the prevalence of sinus rhythm ECG abnormalities in patients with apparent structurally normal heart and VPDs initiating episodes of VF. Unique to our study, VF frequently occurred in the setting of ECG depolarization abnormalities that include a reduced QRS amplitude, QRSf, and/or the presence of an ER pattern. These ECG abnormalities are much more common than noted in a reference population of patients with later coupled VPDs that do not initiate VF.

The

Conclusion

A reduced QRS amplitude (<0.55 mV) in aVF, QRSf in ≥2 contiguous leads, and/or an ER pattern are frequently (81%) observed in patients with VPDs initiating VF and suggest an underlying subclinical structural cardiac abnormality in the presence of apparent normal imaging and EAM studies. VPDs initiating VF typically originate from the distal Purkinje system/PAPs and can be successfully eliminated with catheter ablation.

References (17)

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Funding Sources: This work was supported by the Richard T. and Angela Clark Innovation Fund in Cardiovascular Medicine; the Mark S. Marchlinski EP Research and Education Fund; and the Winkelman Family Fund in Cardiovascular Innovation.

Disclosures: Dr Marchlinski has served as consultant for Abbott Medical, Biosense Webster, Biotronik, and Medtronic Inc. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.

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