Case study - Unexplained syncope may be dangerous

A 31-year-old man ignored faints, writes Dr Keith Barnard.

Mrs Harris brought her husband of six months along to see me. The problem, according to Mrs Harris, was that he had fainted last weekend, and although he didn't want to make a fuss, she was worried about him.

ST segment elevation is characteristic of Brugada syndrome

They had been out for a meal the night before and had enjoyed two bottles of wine. When Mr Harris came down to breakfast the next morning, he said he felt dizzy and nauseous. He then slipped to the floor, banging his head on the table.

Mrs Harris gave a good description of what happened. She had some first aid experience and had checked his pulse and noticed that he was very pale. She had started to panic, she said, because he was unconscious for about two minutes.

She was quite sure there was no fitting or tongue-biting, and no incontinence. When her husband came round, he was not confused, and was talking normally straight away.

Vaso-vagal episode
I examined Mr Harris and found his pulse regular at 74 beats per minute and his BP normal. I thought this was probably a vaso-vagal episode after a night out, and explained this to Mrs Harris. Mr Harris put on an 'I told you so' expression, but his wife was unconvinced.

He had never done anything like this since they had been together, she told me, but said that her husband had confessed in the aftermath that it had happened several times before.

There were never any ill effects, and he had never been to see a doctor about them because they were 'just faints'.

I still was not sure this warranted further investigation, until Mrs Harris accusingly said to her husband, 'What about your Uncle Jim?'

Mr Harris then reluctantly admitted that his father's brother had died suddenly in his thirties, but no-one knew why.

Puzzling ECG
This made me think a little harder - an unexplained, possible cardiac death in a young relative made me start to consider such diagnoses as hypertrophic cardiomyopathy or fatal dysrhythmias. I decided to do an ECG, and the result puzzled me.

It was clearly abnormal, with ST segment elevation in leads V1-V3, and I suspected a possible right bundle branch block. I am no ECG expert, so I referred Mr Harris to our local cardiologist.

I received an enthusiastic letter back from the cardiologist. He explained the ECG findings in detail, pointing out that the ST-elevation was 'downsloping' and the QRS morphology was characteristic of Brugada syndrome.

A history of multiple unexplained episodes of syncope and sudden death in a close family member fitted the pattern exactly. Other situations where sudden cardiac death may occur in a structurally normal heart include long-QT syndrome, and the pre-excitation syndromes.

Some 5 per cent of survivors of cardiac arrest have no clinically identified cardiac abnormality, and roughly half of these are thought to be caused by Brugada syndrome.

Cardiac syndrome
Brugada syndrome was originally described in 1992.1 It consists of the Brugada pattern on an ECG and one or more associated clinical features, including syncopal episodes, documented ventricular fibrillation, self-limiting ventricular tachycardia, a history of sudden cardiac death in a relative less than 45 years of age and evidence of ST-segment elevation in family members.

The cause is an autosomal-dominant genetic defect that results in dysfunction or loss of function of the sodium channel.2 The dysfunction of the cardiac sodium ion channels reduces the sodium current available during the upstroke phase and the early repolarisation of the cardiac action potential.

The average age of presentation is 30 years.

Patients with Brugada syndrome are liable to have malignant ventricular tachyarrhythmias, and these can lead to syncope, cardiac arrest or sudden death. The prevalence of Brugada syndrome is difficult to state with any accuracy, but the current estimate is about 1-5 per 10,000 population in Western countries.

In South East Asia, nearly half of all cases of idiopathic ventricular fibrillation are due to Brugada syndrome.

Some situations may unmask or exacerbate the ECG pattern of Brugada syndrome, such as sodium-channel blockers, alpha-adrenergic agonists, beta-blockers, and some antidepressants. A fever, cocaine use and alcohol abuse may exacerbate it, and electrolyte disturbances such as hyperkalaemia, hypokalaemia, and hypercalcaemia have also been implicated.

Effective management
This is a rare syndrome, and does not mean GPs should refer all cases of syncope. This should be reserved for patients who have had repeated syncopal episodes with ECG abnormalities and/or a family history of sudden death in a young relative.

The only effective treatment is an automatic implantable cardioverter defibrillator (AICD). Drug treatment is ineffective. The circumstances in which such an AICD should be used are not always clear.3

Family members of known cases should be investigated, and some specialists recommend restricted physical activity to reduce the risk of ventricular fibrillation.

Mr Harris was referred to Papworth Hospital, Cambridge, to be assessed for an AICD.

  • Dr Barnard is a former GP in Fareham, Hampshire

References

1. Brugada P, Brugada J. Right bundle branch block, persistent ST segment elevation and sudden cardiac death: a distinct clinical and electrocardiographic syndrome. A multicenter report. J Am Coll Cardiol 1992; 20: 1,391-96.

2. Chen Q, Kirsch G E, Zhang D, et al. Genetic basis and molecular mechanisms for idiopathic ventricular fibrillation. Nature 1998; 392: 293-6.

3. Babuty D, Robin I, Fauchier L et al. Indications for automatic implantable defibrillators in patients with the Brugada syndrome. Ann Cardiol Angeiol 2005; 54: 17-20.

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