Electrocardiographic Parameters and Fatal Arrhythmic Events in Patients With Brugada Syndrome

Objectives This study aimed to determine the usefulness of the combination of several electrocardiographic markers on risk assessment of ventricular fibrillation (VF) in patients with Brugada syndrome (BrS). Background Detection of high-/low-risk BrS patients using a noninvasive method is an important issue in the clinical setting. Several electrocardiographic markers related to depolarization and repolarization abnormalities have been reported, but the relationship and usefulness of these parameters in VF events are unclear. Methods Baseline characteristics of 246 consecutive patients (236 men; mean age, 47.6 +/- 13.6 years) with a Brugada-type electrocardiogram, including 13 patients with a history of VF and 40 patients with a history of syncope episodes, were retrospectively analyzed. During the mean follow-up period of 45.1 months, VF in 23 patients and sudden cardiac death (SCD) in 1 patient were observed. Clinical/ genetic and electrocardiographic parameters were compared with VF/SCD events. Results On univariate analysis, a history of VF and syncope episodes, paroxysmal atrial fibrillation, spontaneous type 1 pattern in the precordial leads, and electrocardiographic markers of depolarization abnormalities (QRS duration >= 120 ms, and fragmented QRS [f-QRS]) and those of repolarization abnormalities (inferolateral early repolarization [ER] pattern and QT prolongation) were associated with later cardiac events. On multivariable analysis, a history of VF and syncope episodes, inferolateral ER pattern, and f-QRS were independent predictors of documented VF and SCD (odds ratios: 19.61, 28.57, 2.87, and 5.21, respectively; p < 0.05). Kaplan-Meier curves showed that the presence/ absence of inferolateral ER and f-QRS predicted a worse/better prognosis (log-rank test, p < 0.01). Conclusions The combination of depolarization and repolarization abnormalities in BrS is associated with later VF events. The combination of these abnormalities is useful for detecting high-and low-risk BrS patients

Anti-tachycardia pacing degenerated fast ventricular tachycardia into undetectable life-threatening tachyarrhythmia in a patient with non-ischemic dilated cardiomyopathy

SummaryA 45-year-old man with dilated cardiomyopathy was admitted to our hospital due to congestive heart failure (CHF). Despite the optimal medical treatment, his condition had not improved because of severe left ventricular dysfunction. Because he experienced non-sustained ventricular tachycardia (VT), a biventricular implantable cardioverter-defibrillator (Bi-V ICD) was implanted for reduction of dyssynchrony and primary prevention of lethal tachyarrhythmia. After discharge, he developed CHF and was transported to our hospital by ambulance. In the ambulance, monomorphic sustained VT with 200bpm suddenly occurred. The ICD detected it as fast VT and anti-tachycardia pacing (ATP) was delivered. After the ATP therapy, RR intervals of VT became irregular and prolonged. Ventricular fibrillation-like electrical activity was recorded by a far-field electrogram from the defibrillator, but the tachycardia cycle length exceeded 400ms which is under the tachycardia detection rate. The device failed to deliver a shock and the patient had to be rescued with an external shock. This is a rare case of fast VT that degenerated into undetectable life-threatening tachyarrhythmia by ATP

Meta-Analysis of Risk Stratification of SCN5A With Brugada Syndrome: Is SCN5A Always a Marker of Low Risk?

Background:SCN5A with Brugada syndrome (BrS) is not commonly considered as an independent risk marker for subsequent cardiac events. However, the risk of SCN5A combined with other clinical characteristics has not been fully investigated.Objectives: The aim of this study is to investigate and evaluate risk stratification and related risk factors of SCN5A in BrS.Methods: The databases of PubMed, EMBASE, Cochrane Library, MEDLINE, Chinese National Knowledge Infrastructure (CNKI) and Wanfang Data were searched for related studies published from January 2002 to May 2018 followed by meta-analysis. The BrS patients who underwent SCN5A gene tests were included. The prognosis and risk stratification of SCN5A combined with symptoms and asymptoms diagnosis in BrS, electrophysiology study (EPS) were then investigated and evaluated. Outcomes were defined as ventricular tachycardia/fibrillation (VT/VF), sudden cardiac death (SCD).Results: Eleven suitable studies involving 1892 BrS patients who underwent SCN5A gene tests were identified. SCN5A (+) was not considered to be a significant predictor of future cardiac events (95% CI: 0.89–2.11; P = 0.15; I2 = 0%). However, SCN5A (+) patients with symptoms at diagnosis revealed a higher prevalence of future VT/VF, SCD compared to SCN5A (–) patients with symptoms at diagnosis. (95% CI: 1.06–3.70; P = 0.03 I2 = 0%) Among asymptomatic patients, the risk did not significantly differ between SCN5A (+) patients and SCN5A (–) patients. (95% CI: 0.51–4.72; P = 0.45 I2 = 0 %). In an investigation involving patients in EPS (–) BrS electrocardiogram (ECG), the risk of SCN5A (+) is higher than that of SCN5A (–) (P &lt; 0.001).Conclusions: In BrS patients with symptoms at diagnosis or EPS (–), the meta-analysis suggests that SCN5A (+) are at a higher risk of arrhythmic events than SCN5A (–)

Brugada syndrome: Recent understanding of pathophysiological mechanism and treatment

Since 1992, Brugada syndrome has gained worldwide recognition as an important cause of sudden cardiac death due to ventricular fibrillation (VF) in the structurally normal heart. Its signature electrocardiography (ECG) pattern consists of ST-segment elevation in the right precordial leads, and the pathophysiological mechanisms of this ST-segment elevation and VF development have been reported to be closely related. However, the precise mechanisms present in Brugada syndrome patients remain unknown. Herein, we will review clinical and experimental evidence, with a focus on the current understanding of the underlying pathophysiological mechanisms of this unique ECG pattern and VF development, and describe the current strategy for management of Brugada syndrome