Hypokalaemia in hypertensive patients treated with diuretics: no increase in cardiac arrhythmias.

Hypokalaemia is a risk factor for the development of cardiac arrhythmias, at least in patients with a cardiac disease, but it is not known whether this applies to subjects with normal hearts. In the present study, 8 young patients with essential hypertension were treated with chlorthalidone for 12 wk followed by a combination of chlorthalidone (50 mg/day) and triamterene (100 mg/day) for 6 wk. This protocol was chosen in order to create different phases in the intra- and extracellular potassium concentrations. At the end of each 6-wk period, blood analyses were performed together with whole body counting for 40K, 24-h electrocardiogram registration, and ergometry. Although plasma potassium concentration and total body potassium decreased significantly in the chlorthalidone period and increased significantly in the period when triamterene was administered together with chlorthalidone, no changes in ectopic activity were seen during either 24-h registration or ergometry. It is concluded that, although hypokalaemia may be dangerous in patients with diseased hearts, a similar risk could not be established in subjects with a normal heart and uncomplicated essential hypertension. Whether the conclusion applies to the average patient with essential hypertension is still a subject of study.