[Torsade de pointes and use of phenothiazine and diuretic]

A 54-year-old woman with recurrent episodes of syncope fainted on admission. An episode of torsade de pointes was registered on electrocardiographic monitoring. We assume that the combined effects of phenothiazine and of hypokalemia (2.6 meq/l) caused by chlorthalidone provoked the condition. Diuretics should be used with caution in patients on phenothiazines.