Local Left Ventricular Epicardial J Waves and Late Potentials in Brugada Syndrome Patients with Inferolateral Early Repolarization Pattern

Triggers of Ventricular Fibrillation in Patients With Inferolateral J-Wave Syndrome

BACKGROUND

There are few data on ventricular fibrillation (VF) initiation in patients with inferolateral J waves.

OBJECTIVES

This multicenter study investigated the characteristics of triggers initiating spontaneous VF in inferolateral J-wave syndrome.

METHODS

A total of 31 patients (age 37 ± 14 years, 24 male) with spontaneous VF episodes associated with inferolateral J waves were evaluated to determine the origin and characteristics of triggers. The J-wave pattern was recorded in inferior leads in 11 patients, lateral leads in 3, and inferolateral leads in 17.

RESULTS

The VF triggers (n = 37) exhibited varying QRS durations (176 ± 21 milliseconds, range 119-219 milliseconds) and coupling intervals (339 ± 46 milliseconds, range 250-508 milliseconds) with a right (70%) or left (30%) bundle branch block (BBB) pattern. Trigger patterns were associated with J-wave location: left BBB triggers with inferior J waves and right BBB triggers with lateral J waves. Electrophysiologic study was performed for 22 VF triggers in 19 patients. They originated from the left or right Purkinje system in 6 and from the ventricular myocardium in 10 and were undetermined in 6. Purkinje vs myocardial triggers showed distinct electrocardiographic characteristics in coupling interval and QRS-complex duration and morphology. Abnormal epicardial substrate associated with fragmented electrograms was identified in 9 patients, with triggers originating from the same region in 7 patients. Catheter ablation resulted in VF suppression in 15 patients (79%).

CONCLUSIONS

VF initiation in inferolateral J-wave syndrome is associated with significant individual heterogeneity in trigger characteristics. Myocardial triggers have electrocardiographic features distinct from Purkinje triggers, and their origin often colocalizes with an abnormal epicardial substrate.

J wave syndromes: What's new?

Among the inherited ion channelopathies associated with potentially life-threatening ventricular arrhythmia syndromes in nominally structurally normal hearts are the J wave syndromes, which include the Brugada (BrS) and early repolarization (ERS) syndromes. These ion channelopathies are responsible for sudden cardiac death (SCD), most often in young adults in the third and fourth decade of life. Our principal goal in this review is to briefly outline the clinical characteristics, as well as the molecular, ionic, cellular, and genetic mechanisms underlying these primary electrical diseases that have challenged the cardiology community over the past two decades. In addition, we discuss our recently developed whole-heart experimental model of BrS, providing compelling evidence in support of the repolarization hypothesis for the BrS phenotype as well as novel findings demonstrating that voltage-gated sodium and transient outward current channels can modulate each other's function via trafficking and gating mechanisms with implications for improved understanding of the genetics of both cardiac and neuronal syndromes.

Fibrosis and Conduction Abnormalities as Basis for Overlap of Brugada Syndrome and Early Repolarization Syndrome

Brugada syndrome and early repolarization syndrome are both classified as J-wave syndromes, with a similar mechanism of arrhythmogenesis and with the same basis for genesis of the characteristic electrocardiographic features. The Brugada syndrome is now considered a conduction disorder based on subtle structural abnormalities in the right ventricular outflow tract. Recent evidence suggests structural substrate in patients with the early repolarization syndrome as well. We propose a unifying mechanism based on these structural abnormalities explaining both arrhythmogenesis and the electrocardiographic changes. In addition, we speculate that, with increasing technical advances in imaging techniques and their spatial resolution, these syndromes will be reclassified as structural heart diseases or cardiomyopathies.

Structurally Abnormal Myocardium Underlies Ventricular Fibrillation Storms in a Patient Diagnosed With the Early Repolarization Pattern

OBJECTIVES

The aim of this study was to investigate the mechanism underlying QRS-slurring in a patient with the early repolarization pattern in the electrocardiogram (ECG) and ventricular fibrillation (VF) storms.

BACKGROUND

The early repolarization pattern refers to abnormal ending of the QRS complex in subjects with structurally normal hearts and has been associated with VF.

METHODS

We studied a patient with slurring of the QRS complex in leads II, III, and aVF of the ECG and recurrent episodes of VF. Echocardiographic and imaging studies did not reveal any abnormalities. Endocardial mapping was normal but subxyphoidal epicardial access was not possible. Open chest epicardial mapping was performed.

RESULTS

Mapping showed that the inferior right ventricular free wall activated the latest with local J-waves in unipolar electrograms. The last moment of epicardial activation concurred with QRS-slurring in the ECG whereas the J-waves in the local unipolar electrograms occurred in the ST-segment of the ECG. Myocardial biopsies obtained from the late activated tissue showed severe fibrofatty alterations in the inferior right ventricular wall where fractionation and local J-waves were present. After ablation, the early repolarization pattern in the ECG disappeared and arrhythmias have been absent since (follow-up 18 months).

CONCLUSIONS

In this patient, the electrocardiographic early repolarization pattern was caused by late activation due to structurally abnormal myocardium. The late activated areas were marked by J-waves in local electrograms. Ablation of these regions prevented arrhythmia recurrence and normalized the ECG.