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[Influence of digoxin upon the exercise ECG of healthy men (author's transl)]
Insights
Cardiac glycosides like digoxin can cause false positives in exercise ECG tests for coronary insufficiency. However, only a third of healthy individuals show these effects, suggesting ECGs can proceed without stopping digitalis therapy.
Area of Science:
- Cardiology
- Pharmacology
Context:
- Exercise electrocardiograms (ECG) are crucial for diagnosing coronary heart disease.
- Cardiac glycoside therapy, including digitalis, can induce S-T segment changes on ECGs.
- These changes may mimic symptoms of coronary insufficiency, leading to potential misdiagnosis.
Purpose:
- To investigate the impact of digoxin on exercise ECG results in healthy individuals.
- To determine the frequency of false-positive S-T segment depressions induced by digoxin.
- To assess the necessity of discontinuing digitalis therapy before exercise ECG examinations.
Summary:
- Digoxin administration to 23 healthy men resulted in heart rate changes and S-T segment depressions in some individuals during exercise ECGs.
- Only 8 out of 23 participants showed S-T depressions that met criteria for coronary insufficiency.
- Plasma digoxin concentrations averaged 1.03 ng/ml in a subset of participants.
Impact:
- The findings suggest that exercise ECGs can be performed without interrupting digitalis therapy in many cases.
- A false-positive result due to digoxin occurs in approximately one-third of healthy individuals.
- If significant S-T depressions arise, the ECG should be repeated after a digitalis-free interval.
Abstract:
Cardiac glycosides may cause in the exercise ECG of healthy persons S-T segment depressions, which imitate a coronary insufficiency. If this method of examination is to be carried out in diagnosing coronary heart disease, it is - therefore - recommended in many cases to discontinue, at all events, an eventual digitals therapy before the examination in order to avoid falsely positive results. 23 healthy men (average age 30.2 years) were applied digoxin of medially quick saturation over seven days. Exertion electrocardiograms at the bicycle ergometer were registered before and after digoxin application. In five further cases, plasma glycoside concentrations were evaluated by 86Rb erythrocyte assay; upon the degree of saturation used, these concentrations - on the sixth and seventh day - amounted to x = 1.03 ng/ml. The following items manifested after digoxin administration, under stress and after resting: Retardation of heart rate, declination of T amplitude, and individually to a very different extent - depression of the S-T segment. After application of digoxin, only 8 of the 23 test persons demonstrated S-T depressions that would have corresponded entirely to the conditions of a "coronary insufficiency". Thus, it appears to be justified to carry out - first of all and in order to exclude the possibility of a coronary insufficiency - an exertion electrocardiogram, without interruption of the glycoside therapy, also in patients who are undergoing a digitalis therapy. The reason for this measure is the fact that in healthy persons only one third of the cases must be expected to show a falsely positive result. If, however, significant S-T depressions occur, the examination has to be repeated after a sufficiently long-lasting glycoside-free interval.