Indapamide induced syncope in a patient with long QT syndrome

A 60-year-old woman who had been successfully treated with atenolol and cardiac pacing for hypertension and long QT syndrome developed recurrent episodes of palpitations and syncope. Several days prior to these episodes, indapamide 2.5 mg/day was taken for better control of hypertension. The episodes were associated with prolongation of QT interval and mild hypokalemia (3.1 MEQ/L). Indapamide was immediately stopped, but the QT remained prolonged 2 days later, although the potassium level was normalized. This case suggests that indapamide can cause potassium independent prolongation of the QT interval, resulting in arrhythmia induced syncope.