ClinicalVentricular TachycardiaSinus rhythm QRS amplitude and fractionation in patients with nonischemic cardiomyopathy to identify ventricular tachycardia substrate and location
Graphical abstract
Introduction
The arrhythmogenic substrate in left ventricular (LV) nonischemic cardiomyopathy (NICM) usually consists of fibrosis interspersed with surviving myocardium.1, 2, 3, 4 The majority of patients with LV NICM and ventricular tachycardia (VT) have a perivalvular substrate that is predominantly septal (S-NICM) or free wall (FW-NICM).5 In patients with S-NICM VT substrate, fibrosis commonly affects the basal midmyocardium and endocardium (ENDO) extending to the anteroseptum, inferoseptum, periaortic LV, aortic cusps, aortic mitral continuity, and right ventricular (RV) septum.6 In contrast, patients with FW-NICM VT substrate have a high prevalence of epicardial (EPI) substrate, and although typically with a basal lateral location, the substrate can extend to or primarily involve the inferior and anterior LV free wall.3,4,7
We hypothesized that the fibrotic process associated with the VT substrate may be reflected on the 12-lead electrocardiogram (ECG) as reduced QRS amplitude and multilead QRS fractionation (QRSf) during sinus or other supraventricular rhythm.4,8,9 The aim of this study was to determine whether, in patients with LV NICM and sustained VT, reduced QRS amplitude and QRSf during sinus rhythm can identify the presence and location of abnormal S-NICM and/or FW-NICM VT substrate.
Section snippets
Study population
We included between February 2019 and November 2020 a prospective cohort of 41 patients with NICM and monomorphic sustained VT (group 1). Patients had an identifiable VT substrate on electroanatomic mapping (EAM), either S-NICM or FW-NICM, and evidence of VT circuit(s) based on activation, entrainment, and/or pacemapping in those distinct regions. VT substrate was defined by the presence of low-voltage, long-duration, fractionated electrograms, split signals, and/or isolated late potentials on
Study cohort characteristics: Group 1
A total of 41 patients met the prospective cohort inclusion criteria with NICM, sustained VT, and defined electroanatomic substrate. Twenty-one (51%) were categorized as having predominant S-NICM (Supplemental Figure 2) and 20 (49%) predominant FW-NICM substrate (Figure 2). Patients with S-NICM and FW-NICM substrate were similar in terms of gender, number of antiarrhythmic drugs attempted before ablation, and LV ejection fraction. However, patients with FW-NICM substrate had a higher prevalence
Discussion
This study of patients with NICM documents the value of QRS amplitude and fractionation as markers of electroanatomic and LGE defined scar and manifest VT. The main findings of our investigation are as follows. (1) Group 1 patients with electroanatomic substrate and manifest VT showed lower QRS amplitude in all leads compared to group 2 patients with prophylactic ICD and no manifest VT with or without LGE. (2) QRS amplitude <0.55 mV in aVF identified with moderate sensitivity (70%) and
Conclusion
In patients with LV NICM, low QRS amplitude in aVF (<0.55 mV) and V6 (<0.96 mV) can help to identify and localize VT substrate. Although multilead QRSf is associated with the presence and likely location of electroanatomic or LGE scar and therefore may provide some benefit in regionalization, it is not specific for VT substrate and is frequently identified in patients without VT.
References (21)
- et al.
Idiopathic dilated cardiomyopathy: analysis of 152 necropsy patients
Am J Cardiol
(1987) - et al.
Isolated septal substrate for ventricular tachycardia in nonischemic dilated cardiomyopathy: incidence, characterization, and implications
Heart Rhythm
(2011) - et al.
Fragmented QRS on twelve-lead electrocardiogram predicts arrhythmic events in patients with ischemic and non-ischemic cardiomyopathy
Heart Rhythm
(2010) - et al.
Site-specific twelve-lead ECG features to identify an epicardial origin for left ventricular tachycardia in the absence of myocardial infarction
Heart Rhythm
(2007) - et al.
Electroanatomic substrate and ablation outcome for suspected epicardial ventricular tachycardia in left ventricular non-ischemic cardiomyopathy
J Am Coll Cardiol
(2009) - et al.
12-Lead electrocardiogram to localize region of abnormal electroanatomic substrate in arrhythmogenicrightventricular cardiomyopathy
JACC Clin Electrophysiol
(2017) - et al.
Catheter ablation of VT in Non-ischaemic cardiomyopathies: endocardial, epicardial and intramural approaches
Heart Lung Circ
(2019) - et al.
Electrocardiogram voltage discordance: interpretation of low QRS voltage only in the limb leads
J Electrocardiol
(2008) - et al.
Prevalence and prognostic significance of fragmented QRS complex in middle-aged subjects with and without clinical or electrocardiographic evidence of cardiac disease
Am J Cardiol
(2014) - et al.
Extent of myocardial fibrosis and cellular hypertrophy in dilated cardiomyopathy
Am J Cardiol
(1986)
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The Diagnostic Value of the 12-Lead ECG in Arrhythmogenic Left Ventricular Cardiomyopathy: Novel ECG Signs
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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 a 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.