A 40 year old man presented to the emergency department after losing consciousness while driving his car. He had felt nauseous and light headed before managing to slow down and stop. A witness who stopped to help found him slumped unconscious over the steering wheel, and he regained consciousness a few seconds later. On arrival in hospital he was fully alert although he felt light headed and had mild chest discomfort.

He had been investigated previously for episodes of dyspnoea. Lung function tests, exercise tolerance tests, and 24 hour Holter monitoring had been unremarkable though ST segment elevation had been noted on his electrocardiogram (ECG). In the emergency department, physical examination was unremarkable though his resting ECG again showed ST segment elevation in the anterior precordial leads (fig 1). These changes were identical to those seen in the ECGs performed three years previously which had been faxed to the emergency department.

A provisional diagnosis of vasovagal syncope or syncope secondary to an arrhythmia was made and he was admitted for further investigation. ECGs performed over the following 24 hours …