A case of Brugada syndrome in which diurnal ECG changes were associated with circadian rhythms of sex hormones.

We describe a thought-provoking case of Brugada syndrome in which a relationship between the diurnal electrocardiogram (ECG) changes and sex hormone levels was observed. A 36-year-old man who experienced cardiac arrest was referred to our hospital. He had a family history of sudden cardiac death. The 12-lead ECG exhibited a mild coved type ST-segment elevation in leads V1 and V2, which was enhanced by intravenous pilsicainide injection. Hence, this case was diagnosed as Brugada syndrome. The circadian rhythm of the serum testosterone level revealed low levels in the daytime (1.66-1.99 ng/mL) and high levels (2.52-3.42 ng/mL) in the nighttime. Interestingly, augmentation of the ST segment elevation and widening of the P wave were observed at around 2:00 AM, when the serum testosterone was recorded at its highest. Our report discusses the influence of the circadian rhythms of sex hormones on the ECG changes in Brugada syndrome.