A 62-year-old woman known with a depressive disorder but unremarkable cardiovascular history was admitted to our emergency department in a state of unconsciousness. Her husband had found her unconscious at home and called an ambulance. She had no history of syncope or suicidality. Physical examination demonstrated a Glasgow Coma Scale of E₁M₅V₁ without any lateralising neurological symptoms. She was haemodynamically stable, but was intubated because of failure to maintain airway tone due to unconsciousness. She had no fever. Laboratory results showed: sodium 150 mmol/l, potassium 3.2 mmol/l, a normal glomerular filtration rate, haemoglobin 7.6 mmol/l; normal thrombocytes and leucocytes. The ECG on admission is shown in Fig. 1.