Cardiac arrhythmias in hypertensive outpatients on various diuretics. Correlation between incidence and serum potassium and magnesium levels.

Twenty-four hypertensive out-patients (WHO I) underwent an ambulatory 24-hour electrocardiogram-monitoring both before and after 8 weeks treatment with either hydrochlorothiazide (20-50 mg/day, N = 6), indacrinone (50-100 mg/day, N = 6) or indacrinone plus amiloride (50-100 mg and 5-10 mg/day, N = 12) in a double-blind fashion in 3 parallel groups. A 4-weeks placebo run-in period preceded the active treatment. Serum potassium fell significantly in the hydrochlorothiazide group (p less than 0.001) and in the indacrinone group (p less than 0.005). Serum magnesium values remained unchanged. In 4 out of the 24 patients ventricular ectopic activity increased but there was no correlation with changes in serum potassium or magnesium values in these patients. Treatment with different diuretics had a similar influence on the occurrence of ventricular extrasystoles.