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Hypokalaemia in hypertensive patients treated with diuretics: no increase in cardiac arrhythmias
Insights
Hypokalaemia, or low potassium levels, does not appear to increase cardiac arrhythmia risk in individuals with healthy hearts, even those with essential hypertension. This study found no changes in ectopic activity despite induced potassium fluctuations.
Area of Science:
- Cardiology
- Nephrology
- Pharmacology
Background:
- Hypokalaemia (low potassium) is a known risk factor for cardiac arrhythmias in patients with heart disease.
- The risk of hypokalaemia-induced arrhythmias in individuals with normal hearts is not well-established.
Purpose of the Study:
- To investigate whether hypokalaemia increases the risk of cardiac arrhythmias in young patients with essential hypertension and normal hearts.
- To assess the relationship between induced changes in intra- and extracellular potassium concentrations and cardiac electrical activity.
Main Methods:
- Eight young patients with essential hypertension were enrolled.
- A 12-week treatment with chlorthalidone was followed by a 6-week treatment with chlorthalidone and triamterene.
- Potassium levels (plasma and total body via 40K counting), 24-hour electrocardiogram, and ergometry were assessed.
Main Results:
- Chlorthalidone significantly decreased plasma and total body potassium.
- The addition of triamterene significantly increased potassium levels.
- No significant changes in ectopic activity were observed during either treatment phase on 24-hour ECG or ergometry.
Conclusions:
- Hypokalaemia does not appear to pose a similar risk for cardiac arrhythmias in subjects with normal hearts and uncomplicated essential hypertension as it does in patients with cardiac disease.
- Further studies are needed to determine if these findings apply to the general population with essential hypertension.
Abstract:
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.