Transient loss of consciousness in a patient with a Brugada like ECG.

Syncope in a patient with a Brugada syndrome channelopathy carries significant prognostic implications and warrants consideration of implantable cardioverter defibrillator (ICD) implantation. We report a case of a 62-year-old gentleman who presented with a transient loss of consciousness and an electrocardiogram (ECG) suggestive of type 1 Brugada syndrome. Further investigation revealed evidence of a silent myocardial infarction and negative ventricular tachycardia stimulation and Ajmaline testing. Careful review of the ECG's subsequently showed the type 1 pattern was present in only V1.

Case Report

A 62-year-old man had a transient loss of consciousness (TLOC) whilst driving. He had no prior symptoms and had been in excellent health. The initial electrocardiogram (ECG) (Figure 1A) was felt to be suggestive of a type 1 Brugada and he was admitted for consideration of implantable cardioverter defibrillator (ICD) implantation. Serial troponins were negative. Echocardiography revealed a posterolateral wall motion abnormality. Invasive coronary angiography showed angiographically normal coronary arteries but left ventriculography revealed inferolateral hypokinesis. Cardiac MR imaging (CMR) confirmed the wall motion abnormality and showed a significant area of late subendocardial gadolinium enhancement (LGE) consistent with an infarct. The patient was a non-smoker with favourable lipid profile. A cardiac computed tomography (CT) showed a zero calcium score and again confirmed normal coronary arteries and an area of hypo enhancement (Figure 1B) consistent with infarction similar to the LGE on CMR. Transesophageal echocardiography excluded any valvular abnormality such as a papillary fibroelastoma. An electrophysiology and ventricular tachycardia stimulation test showed no inducibility. An Ajmaline test was carried out and was felt to be negative (Figure 1C). ECG's three years earlier revealed a similar pattern. It is assumed he suffered a previous silent myocardial infarction in the presence of normal coronary arteries and this resulted in a Brugada pattern ECG. Careful subsequent review revealed that the type 1 pattern was actually only present in V1, thus not fulfilling the consensus conference criteria. The cause of the TLOC is unknown but he has remained asymptomatic for over 12 months and has resumed driving.

Figure 1

A) Initial electrocardiogram, suggestive of a type 1 Brugada; B) Cardiac computed tomography, showing an area of hypo enhancement consistent with infarction; C) A negative Ajmaline test.

Discussion

Brugada syndrome is a familial autosomal dominant disease, which has an increased risk of sudden cardiac death and may present with a history of syncope.[1] The diagnosis is made on the ECG showing characteristic cove-shaped ST elevation in leads V(1) to V(3) in the absence of structural heart disease, electrolyte disturbance or ischaemia.[2] There are three different types, which can be identified by the ECG pattern. Type 1 is characterised by a prominent coved ST elevation (> 2 mm above baseline) followed by a negative T wave in lead V1-V3 and this pattern must be in more than 1 lead. Type 2 has a high take off pattern, but has a gradually descending ST segment elevation (> 1 mm above baseline) with either a positive or biphasic T wave in leads V1-V3. Type 3 has right precordial ST segment elevation (> 1 mm above baseline), which is either coved, or saddle back shaped.[3] However, both type 2 and 3 electrocardiogram patterns are no longer considered to be a true Brugada syndrome.

The ECG pattern is important to identify as the first manifestation of the disease maybe sudden death and this is usually due to either ventricular tachycardia of ventricular fibrillation.[4] It is important to identify which type of Brugada pattern is present: type 1 carries a high probability for the disease.[5]

The diagnosis of suspected Brugada syndrome can be difficult and a type 2 or 3 pattern may only manifest after administration of a sodium channel blocker such as Ajmaline.[6] A negative ajmaline tests does however exclude a diagnosis of Brugada syndrome. Syncope in a patient with a Brugada syndrome channelopathy carries significant prognostic implications and warrants consideration of ICD implantation. Brugada pattern ECG's have been described with exposure to various chemical agents including certain antibiotics, cocaine and may also be unmasked by respiration or fever.[7] There are multiple causes other than cardiac ischaemia for acquired ST elevation in the right precordial leads. In some healthy young people, particularly black men, the ST segment can be elevated by 1–4 mm and this is a normal variant. In addition, left bundle branch block, early repolarisation and ventricular hypertrophy can cause ST segment elevation in the right precordial leads.[8]

In our case the patient had an ECG pattern, which was suggestive of a type 1 Brugada Syndrome, and a history of syncope. He was thoroughly investigated with ajmaline testing and ventricular stimulation, which were all normal. The ajmaline test was undertaken to try and confirm the diagnosis, as there was only a suspicion of type 1 Brugada syndrome, as it did not fully fit the diagnostic criteria. His echocardiogram, coronary CT and MR scan were all suggestive of myocardial infarction. Brugada syndrome can only be diagnosed after elimination of both cardiac and extra cardiac causes. We excluded both ischaemia and right ventricular infarction.

This case highlights the possibility that an underlying structural abnormality may be responsible for a Brugada like ECG in the absence of a channelopathy. It is rare for myocardial infarction to cause chronically raised ST segments without an aneurysm, but this can occur. Having excluded coronary ischaemia with a normal coronary angiogram and CT calcium score, the patient was further investigated with a Cardiac MR, which confirmed a wall motion abnormality and showed a significant area of late subendocardial gadolinium enhancement (LGE) consistent with an infarct. Generally an acute anteroseptal or isolated right ventricular myocardial infarction will lead to the electrocardiogram changes seen in our case. We concluded that the patient suffered a previous silent myocardial infarction in the presence of normal coronary arteries and this resulted in a Brugada pattern ECG.

In addition, if a patient presents with a suspicious ECG and a history of transient loss of consciousness they should be investigated fully so Brugada syndrome is not missed. However, great care in ECG interpretation with careful reference to the consensus conference criteria is essential.