Syncope and Brugada-like ECG pattern in a patient with syndrome of inappropriate antidiuretic hormone secretion (SIADH)

Abstract

Syncope is a brief loss of consciousness caused by reduced blood flow to the brain, characterised by sudden onset, short duration and full recovery without intervention. Anamnesis, physical examination and other diagnostic tests such as laboratory analysis and electrocardiogram (ECG) can be conducted to identify the underlying cause of syncope. A Brugada pattern on an ECG in individuals with syndrome of inappropriate antidiuretic hormone secretion (SIADH) who have syncope symptoms may indicate cardiac issues. A 69-year-old man with hypertension and a history of smoking presented with syncope. His vital signs were within normal limits, with no signs of a neurological deficit. The patient met the diagnostic criteria for SIADH, as evidenced by the presence of hyponatraemia (Na 118 mmol/l), a hyperosmolar condition and euvolemia. Upon arrival, a twelve-lead ECG showed ST-segment anomalies that reflected a Brugada ECG pattern. No ventricular arrhythmias were detected during the 24-hour Holter monitoring. Coronary angiography revealed no abnormalities in the coronary arteries. The ECG demonstrated the normalisation of ST elevations and the disappearance of the Brugada ECG pattern after the correction of hyponatraemia. After three months of follow-up the patient, with a normal sodium level, had no episodes of syncope.