Article

Long-term prognosis of individuals with right predordial ST-elevation - Brugada syndrome

Westfälische Wilhelms University Hospital, Department of Cardiology and Angiology, Münster, Germany.
Circulation (Impact Factor: 14.95). 05/2005; 111(3):257-63. DOI: 10.1161/01.CIR.0000153267.21278.8D
Source: PubMed

ABSTRACT Brugada syndrome is an arrhythmogenic disease characterized by an ECG pattern of ST-segment elevation in the right precordial leads and an increased risk of sudden cardiac death as a result of ventricular fibrillation. Controversy exists with regard to risk stratification and therapeutic management, particularly in asymptomatic individuals.
A total of 212 individuals (mean age, 45+/-6 years) with a type 1 Brugada ECG pattern were studied. Of these, 123 (58%) were asymptomatic, 65 (31%) had > or =1 syncope of unknown origin, and 24 (11%) had to be resuscitated because of ventricular fibrillation. In 125 individuals (59%), a spontaneous type 1 ECG was recorded. In the remaining, drug challenge with a class I antiarrhythmic agent unmasked a Brugada ECG. The mean ST elevation was 2.3+/-1.2 mm in symptomatic patients and 1.9+/-1.5 mm in asymptomatic individuals (P=0.04). During a mean follow-up of 40+/-50 months, 4 of the 24 patients (17%) with aborted sudden cardiac death and 4 of 65 (6%) with a prior syncope had a recurrent arrhythmic event, whereas only 1 of 123 asymptomatic individuals (0.8%) had a first arrhythmic event. Four of 9 patients with arrhythmic events during follow-up were not inducible during programmed electrical stimulation. A previous history of aborted sudden death or syncope and the presence of a spontaneous type 1 ECG were predictors of adverse outcome.
The present study reports data on a large population of individuals with a type 1 Brugada ECG pattern with the longest follow-up reported so far. A very low incidence of severe arrhythmic events, particularly in asymptomatic individuals, was found during follow-up. In the presence of very few arrhythmic events on follow-up, programmed electrical stimulation showed very little accuracy in predicting outcome.

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    ABSTRACT: Brugada syndrome (BrS) is a condition characterized by a distinct ST-segment elevation in the right precordial leads of the electrocardiogram and, clinically, by an increased risk of cardiac arrhythmia and sudden death. The condition predominantly exhibits an autosomal dominant pattern of inheritance with an average prevalence of 5:10,000 worldwide. Currently, more than 100 mutations in seven genes have been associated with BrS. Loss-of-function mutations in SCN5A, which encodes the alpha-subunit of the Na(v)1.5 sodium ion channel conducting the depolarizing I(Na) current, causes 15-20% of BrS cases. A few mutations have been described in GPD1L, which encodes glycerol-3-phosphate dehydrogenase-1 like protein; CACNA1C, which encodes the alpha-subunit of the Ca(v)1.2 ion channel conducting the depolarizing I(L,Ca) current; CACNB2, which encodes the stimulating beta2-subunit of the Ca(v)1.2 ion channel; SCN1B and SCN3B, which, in the heart, encodes beta-subunits of the Na(v)1.5 sodium ion channel, and KCNE3, which encodes the ancillary inhibitory beta-subunit of several potassium channels including the Kv4.3 ion channel conducting the repolarizing potassium I(to) current. BrS exhibits variable expressivity, reduced penetrance, and "mixed phenotypes," where families contain members with BrS as well as long QT syndrome, atrial fibrillation, short QT syndrome, conduction disease, or structural heart disease, have also been described.
    Human Mutation 07/2009; 30(9):1256-66. DOI:10.1002/humu.21066 · 5.05 Impact Factor
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    Journal of Cardiovascular Electrophysiology 05/2006; 17(6):577 - 583. DOI:10.1111/j.1540-8167.2006.00455.x · 2.88 Impact Factor
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    ABSTRACT: The Brugada syndrome (BrS) is a malignant genetically-determined arrhythmic syndrome manifesting as syncope or sudden cardiac death (SCD) in individuals with structurally normal hearts. The diagnosis of the BrS is mainly based on the presence of a spontaneous or Na+-channel blocker induced characteristic electrocardiographic (ECG) pattern (“type 1” or “coved” Brugada ECG pattern) typically seen in leads V1 and V2 recorded from the 4th to 2nd intercostal (i.c.) spaces. This pattern needs to be distinguished from similar ECG changes due to other causes (“Brugada ECG phenocopies”). This review focuses mainly on the ECG-based methods for diagnosis and arrhythmia risk assessment in the BrS. Presently the main unresolved clinical problem is the identification of those patients at high risk of SCD who need implantable cardioverter-defibrillator (ICD) which is the only therapy with proven efficacy. Current guidelines recommend ICD implantation only in patients with spontaneous type 1 ECG pattern and either history of aborted cardiac arrest or documented sustained VT (class I) or syncope of arrhythmic origin (class IIa) because they are at high risk of recurrent arrhythmic events (up to 10% or more annually for those with aborted cardiac arrest). The majority of BrS patients are asymptomatic when diagnosed and considered to have low risk (around 0.5% annually) and therefore not indicated for ICD. The majority of SCD victims in the BrS, however, have had no symptoms prior to the fatal event and therefore were not protected with an ICD. While some ECG markers such as QRS fragmentation, infero-lateral early repolarisation, abnormal late potentials on signal-averaged ECG are known to be linked to increased arrhythmic risk they are not sufficiently sensitive or specific. Potential novel ECG-based strategies for risk stratification are discussed based on computerised methods for depolarisation and repolarisation analysis, a composite approach targeting several major components of ventricular arrhythmogenesis and the collection of large digital ECG databases in genotyped BrS patients and their relatives.
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