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DIURETICS, HYPOKALEMIA, AND ARRHYTHMIA.

Millions of Americans use thiazide diuretics for hypertension, but some data suggest that these drugs are associated with an increased risk of sudden death. These investigators performed a double-blind trial in 233 hypertensive men (ages 35 to 70) to determine whether diuretics might cause electrolyte disturbances leading to ventricular arrhythmias.

Patients were randomized to receive one of six regimens: 50 mg/d of hydrochlorothiazide (HCTZ); HCTZ with potassium supplements; HCTZ with potassium and magnesium supplements; HCTZ and triamterene; chlorthalidone (50 mg/d); or placebo. After two months, serum potassium levels were significantly lower (by 0.4 to 0.88 mmol/l) in patients taking HCTZ than in those taking placebo, even when HCTZ was supplemented. The drop in potassium was even greater with chlorthalidone than with HCTZ. Severe hypokalemia (3.0 mmol/l or less) occurred in 30 of 90 subjects taking chlorthalidone or HCTZ alone; these patients were nearly twice as likely as those with higher potassium levels to have frequent or complex ventricular arrhythmias on ambulatory monitoring. The various regimens had no effect on magnesium levels, and hypomagnesemia was not a risk factor for arrhythmias.

These findings suggest that severe hypokalemia and associated arrhythmias can develop some patients receiving diuretics. While many patients do not require potassium supplementation, careful monitoring of potassium levels is indicated during the initiation of diuretic therapy.

— THL

Published in Journal Watch General Medicine March 3, 1992

Citation(s):

Siegel D et al. Diuretics, serum and intracellular electrolyte levels, and ventricular arrhythmias in hypertensive men. JAMA 1992 Feb 26 267 1083-1089.

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• HCTZ arrhythmia
  MB Carney, 1 Oct 2009 2:34 PM EST
  I am a 48-year-old female who last year started a low-dose (12.5) a day of HCTZ and within a month... [more]