Brief reports

Prevalence of the Brugada syndrome in an apparently healthy population

Brugada syndrome (BrS) is one of the main inherited arrhythmia syndromes causing ventricular fibrillation (VF) and sudden cardiac death in young to middle-aged men, especially in Asians. The diagnosis of BrS is based on spontaneous or drug-provoked type 1 Brugada electrocardiogram. The current reliable therapy for BrS patients with VF history is the implantation of an implantable cardioverter-defibrillator. As for BrS patients without VF history, how asymptomatic BrS patients should effectively be treated is still uncertain because risk stratification of the BrS is still inadequate. Various parameters and combinations of several parameters have been reported for risk stratification of BrS. The SCN5A gene is believed to be the only gene that is responsible for BrS, and it has been reported to be useful for risk stratification. This review focuses on risk stratification of BrS patients, and focuses specifically on BrS patients of Asian descent.

Brugada syndrome (BrS) is an inheritable disease with an increased risk of sudden cardiac death. Although several score systems have been proposed, the management of children with BrS has been inconsistently described.

The purpose of this study was to identify the characteristics, outcome, and risk factors associated with cardiovascular and arrhythmic events (AEs) in children younger than 12 years with BrS.

In this single-center case series, all children with spontaneous or drug/fever-induced type 1 Brugada electrocardiographic (ECG) pattern and younger than 12 years at the time of diagnosis were enrolled.

Forty-three patients younger than 12 years at the time of diagnosis were included. The median follow-up was 3.97 years (interquartile range 2–12 years). In terms of first-degree atrioventricular block, premature beats, nonmalignant AEs, malignant AEs, and episodes of syncope, no significant differences were observed either between patients with spontaneous and drug/fever-induced type 1 Brugada ECG pattern or between female and male patients (except a significant difference between female and male patients for first-degree atrioventricular block). A higher incidence of malignant AEs was observed in patients with syncope (3 of 8 [37.5%] vs 0 of 35 [0%]; P = .005) than in patients without syncope. SCN5A mutations were associated with a higher occurrence of malignant AEs (3 of 14 [21.4%] vs 0 of 25 [0%]; P = .04) compared with no SCN5A mutations.

A spontaneous type 1 Brugada ECG pattern is not associated with a higher incidence of syncope, first-degree atrioventricular block, premature beats, nonmalignant AEs, and malignant AEs than the drug/fever-induced type 1 Brugada ECG pattern. Syncope events are correlated with an increased incidence of malignant AEs. Moreover, SCN5A mutations are associated with a higher occurrence of malignant AEs.

The occurrence of cardiac electrical abnormalities such as repolarization disorders in patients with epilepsy was previously documented and may, in part, clarify the mechanism of sudden unexpected death in those patients. The aim of this study was to investigate the frequency of cardiac repolarization disorders among patients with epilepsy and whether specific demographic- or disease-related features were associated with their occurrence.

This cross-sectional study was carried out on 1000 subjects with epilepsy who were compared with age- and sex-matched 2500 subjects without epilepsy. Clinical assessment, which included careful history taking and examination, was carried out for all participants in addition to resting 12-lead electrocardiogram (ECG) recording. Electrocardiograms were reviewed by experienced cardiologists. Electrocardiogram intervals were measured, and morphological abnormalities were identified using standard guidelines.

Repolarization abnormalities were found in 142 (14.2%) patients with epilepsy. A statistically significant elevation in percentage of corrected QT interval (QTc) prolongation (both severe and borderline) among patients with epilepsy compared with controls was documented (8.4% vs 2%, P < 0.001). Epilepsy increased the likelihood of hosting prolonged QTc more than 4 times (95% confidence interval: 3.175–6.515; odds ratio: 4.548; P < 0.001). Affected patients were significantly older (95% confidence interval: 1.012–1.044; odds ratio: 1.027; P = 0.001), and the abnormality was significantly more prevalent among those with poor seizure control (95% confidence interval: 1.103–2.966; odds ratio: 1.809; P = 0.019). On the other hand, early repolarization (ER) pattern and Brugada type ECG pattern (BP) were significantly more prevalent in subjects without epilepsy.

Corrected QT interval prolongation (both severe and borderline) was more prevalent among patients with epilepsy, especially if uncontrolled or elderly. Electrocardiogram should be established as a part of the diagnostic workup of epilepsy in order to identify such electrocardiographic abnormality.

Hay patrones electrocardiográficos asociados a mayor riesgo de muerte súbita por arritmias ventriculares. En España no existe información acerca de su prevalencia en la población. El objetivo es estudiar la prevalencia de estos patrones, así como los factores clinicoepidemiológicos asociados a su presencia.

Subanálisis del estudio OFRECE en el que se estudió la prevalencia de patrones electrocardiográficos de síndrome de Brugada o anomalías del intervalo QT en una muestra representativa de la población española ≥ 40 años. Se dispuso de datos clínicos y electrocardiogramas de todos los participantes. Los electrocardiogramas fueron evaluados de forma independiente por 2 cardiólogos y, en caso de desacuerdo, se consultó con un tercero. Se analizaron las prevalencias ponderadas y los factores clínicos asociados a patrones tipo Brugada o a anomalías del segmento QT.

Se evaluó a 8.343 individuos (59,2 años, 52,4% mujeres) y se detectaron 12 casos de patrón Brugada (tipo 1, 2 casos; tipo 2, 10 casos; prevalencia ponderada, 0,13%). Para el análisis del QT corregido (QTc) se excluyó a los participantes con bloqueo de rama izquierda o ritmos no sinusales. Las prevalencias ponderadas fueron: QTc corto (< 340 ms) 0,18%, QTc borderline (441-469 ms) 8,33%, QTc largo (criterio ≥ 470 ms) 1,01% y QTc largo (criterio ≥ 480 ms) 0,42%.

El 0,6-1,1% de la población española de edad ≥ 40 años presenta un patrón electrocardiográfico de riesgo de muerte súbita (síndrome de Brugada, QT largo o QT corto).

Some electrocardiographic patterns are associated with an increased risk of sudden cardiac death due to ventricular arrhythmias. There is no information on the prevalence of these patterns in the general population in Spain. The objective of this study was to analyze the prevalence of these patterns and associated clinical and epidemiological factors.

This subanalysis of the OFRECE study selected a representative sample of the Spanish population aged ≥ 40 years. We studied the presence or absence of electrocardiographic patterns of Brugada syndrome and QT interval abnormalities. Clinical data and electrocardiograms were available in all participants. Electrocardiograms were evaluated by 2 cardiologists and a third cardiologist was consulted if there was disagreement in the diagnosis. We calculated the weighted prevalence and clinical factors associated with the presence of Brugada-type patterns or QT segment abnormalities.

Overall, 8343 individuals were evaluated (59.2 years, 52.4% female). There were 12 Brugada cases (type 1, 2 cases; type 2, 10 cases; weighted prevalence, 0.13%). For corrected QT (QTc) analysis, we excluded participants with left bundle branch block or without sinus rhythm. Weighted prevalences were as follows: short QTc (< 340 ms) 0.18%, borderline QTc (441-469 ms) 8.33%, long QTc (≥ 470 ms criterion) 1.01% and long QTc (≥ 480 criterion) 0.42%.

A total of 0.6% to 1.1% of the Spanish population aged ≥ 40 years has an electrocardiographic pattern associated with a higher risk of sudden death (Brugada syndrome, long QT, or short QT).

Full English text available from: www.revespcardiol.org/en

El síndrome de Brugada es una canalopatía caracterizada por alteraciones basales en la repolarización en el electrocardiograma y la aparición de muerte súbita en algunos pacientes que lo padecen.

El diagnóstico se hace en base a los hallazgos electrocardiográficos y/o de estudio genético. Dado que las alteraciones electrocardiográficas son dinámicas y pueden variar en función del momento y de las circunstancias en el mismo paciente, puede ser necesaria la realización de pruebas farmacológicas para desenmascarar esas alteraciones y establecer el diagnóstico. El estudio electrofisiológico para la estratificación del riesgo tiene un papel controvertido. Las pruebas genéticas pueden tener un papel importante, aunque también muestran limitaciones significativas.

El tratamiento para pacientes sintomáticos que han presentado síncopes no explicados por otras causas o muerte súbita es el implante de un desfibrilador. En algunos casos puede ser necesario el uso de tratamiento médico adyuvante para disminuir los episodios de arritmias ventriculares o durante una tormenta arrítmica. Recientemente se ha propuesto la ablación del sustrato proarrítmico como otra opción de tratamiento.

Brugada syndrome is a channelopathy characterized by baseline alterations in repolarization on the electrocardiogram and the occurrence of sudden death in some patients suffering from it.

The diagnosis is made based on electrocardiographic and/or genetic studies. Since electrocardiographic alterations are dynamic and may vary according to the moment and the circumstances in the same patient, it may be necessary to perform pharmacological tests to unmask these alterations and establish the diagnosis. The electrophysiological study for risk stratification has a controversial role. Genetic tests may play an important role, but they also show significant limitations.

The treatment for symptomatic patients who have presented syncope not explained by other causes or sudden death is the implantation of a defibrillator. In some cases the use of adjuvant medical treatment may be necessary to reduce ventricular arrhythmia episodes or during an arrhythmic storm. Recently, pro-arrhythmic substrate ablation has been proposed as another treatment option.