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• ABOUT BRUGADA SYNDROME
  Raquel Fuentes Manso
  Published on: 17 January 2002

• Published on: 17 January 2002

  ABOUT BRUGADA SYNDROME

  • Raquel Fuentes Manso, MD
  • Other Contributors:
    • Peter Geelen, Maximo Rivero Ayerza, Pedro Brugada.

  Dear Editor

  The question about how we should manage an asymptomatic individual with Brugada syndrome (BS) is not easy to answer. In the case reported, the patient has remained asymptomatic for years (first ECG in 1987) but despite of this, he is carrier of a disease with demonstrated association with arrhythmic death, sometimes the first manifestation in this population. Also, sudden death (SD) related to the syn...

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  Dear Editor

  The question about how we should manage an asymptomatic individual with Brugada syndrome (BS) is not easy to answer. In the case reported, the patient has remained asymptomatic for years (first ECG in 1987) but despite of this, he is carrier of a disease with demonstrated association with arrhythmic death, sometimes the first manifestation in this population. Also, sudden death (SD) related to the syndrome is higher in symptomatic families. In other genetically determined diseases, a family history of SD is a predictive risk factor of SD. This has not been proven in BS.[1]

  There is no doubt that symptomatic patients must be protected with an implantable cardioverter defibrillator (ICD). Asymptomatic individuals, either with spontaneously abnormal ECG as the case discussed, or with abnormal ECG after administration of drugs, should undergo an electrophysiologic study (EPS). If inducible, then an ICD should be recommended. HV measurement is of interest as up to 50% of BS have a prolonged HV reflecting conduction disturbances.[2] Pharmacologic testing with an intravenous sodium channel blocker should be performed in patient's relatives for screening of possible carriers of the disease. There is a 100% correlation between the results of the test and the genotype.[3]

  New data on asymptomatic individuals with a follow up of 3 years have been recently presented.[4] A total of 16 SDs occurred in 190 asymptomatic patients with BS (111 had spontaneously abnormal ECG and 79 had abnormal ECG after administration of an antiarrhythmic drug). All SDs occurred in the group with spontaneously abnormal ECG. EPS was performed in 136 subjects, of these, 45 were inducible and 91 were not. Six SDs occurred in inducible patients (6/45, 13.33%) and 1 SD in those not inducible (1/91, 1.09%). In 9 patients with SD no EPS was performed. Therefore, inducible patients with spontaneously abnormal ECG have an increased risk of SD (13.33%) compared to those not inducible (1%). But still risk does exist in this latter group. There is also the limitation of the 9 SDs in individuals in whom EPS was not performed.

  It is a fact that asymptomatic individuals may become symptomatic during follow up and at present we don't know how to identify them. Actually all symptomatic patients were carriers of the disease and asymptomatic until the moment they developed the first symptoms. Efforts should be made to find out predictive markers of SD in this subgroup. But, no matter the result of the EPS, the threshold for ICD implantation should be low in asymptomatic patients with a malignant family history. No deaths have occurred in patients implanted with an ICD. Some questions still remain. Is previous syncope predictive of SD? Being the peak incidence of symptoms around the fourth decade of life, is there a higher risk in younger patients as compared to the older ones? Is the magnitude of the ST segment elevation related to the occurrence of arrhythmias? Also, taking into account the data presented before, it seems that individuals with spontaneously abnormal ECG are at higher risk than those with abnormal ECG only after drug challenge. Does the fact that up to 40% of symptomatic patients normalise the ECG during follow up have any predictive value?

  Finally, we would like to discuss the study carried out by Hermida et al.,[5] pointed in the article as showing 0% cardiovascular mortality of asymptomatic patients with BS over a follow up of 49 months. In this study, diagnosis of BS was made on the basis of the ECG pattern (ST segment elevation of at least 0.1 mm in leads V1-V3). Prevalence was found to be 6.1% (61 of 1000 subjects analysed) much higher than the prevalence reported by other studies. Only 1 of the 61 individuals exhibited a coved- type ST segment elevation (shown in the publication), characteristic of BS and similar to the first cases reported in 1992. This subject had a history of unexplained syncopes and resulted inducible in the EPS. The other 60 individuals had an ECG with a saddle back-type ST segment elevation (one of these is also shown in the article, and looks only "suspicious" of BS). As the authors say, probably not all the subjects with saddle back-type ST segment elevation had BS (early repolarization may show a similar pattern). These individuals should have been exposed to pharmacological testing to confirm or exclude the diagnosis. It seems reasonable to think that an overestimation of BS occurred in the study population, so the lack of mortality can be related to the fact that only a small number of the subjects really had BS.

  References
  (1) Brugada P, Brugada R, Brugada J. Sudden death in high risk family members: Brugada syndrome. Am J Cardiol 2000;86(suppl):40K-43K.
  (2) Brugada P, Brugada J. Right bundle branch block, persistent ST elevation and sudden cardiac death: a distinct clinical and electrocardiographic syndrome. J Am Coll Cardiol 1992;20:1391-6.
  (3) Brugada J, Brugada R, Wang Q, et al. Unmasking of genotype and phenotype abnormalities by administration of class I antiarrhythmic drugs in patients with sudden death (abstract). Eur Heart J 1998;19:557.
  (4) Brugada J, Brugada R, Antzelevitch C, et al. Arrhythmic events in patients with right bundle branch block and ST segment elevation in right precordial leads (abstract). Eur Heart J 2001;22:17.
  (5) Hermida J, Lemoine J, Bou Aoun F, et al. Prevalence of the Brugada syndrome in an apparently healthy population. Am J Cardiol 2000;86:91-4.

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  Conflict of Interest:
  None declared.

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