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Unexpected effects of treating hypertension in men with electrocardiographic abnormalities: a critical analysis
Insights
Diuretic therapy may increase coronary heart disease (CHD) risk, particularly sudden death, in hypertensive men with specific ECG abnormalities. This risk might stem from hypokalemia and left ventricular hypertrophy, warranting further investigation.
Area of Science:
- Cardiology
- Pharmacology
- Hypertension Research
Background:
- The link between diuretic use and coronary heart disease (CHD) mortality, especially sudden death, remains controversial.
- Initial findings from the Multiple Risk Factor Intervention Trial (MRFIT) suggested a potential adverse effect of diuretic therapy in hypertensive men with specific electrocardiographic abnormalities.
Purpose of the Study:
- To investigate the controversial relationship between diuretic therapy and increased risk of coronary heart disease (CHD) mortality.
- To explore potential mechanisms linking diuretic use, electrocardiographic abnormalities, and sudden cardiac death in hypertensive patients.
Main Methods:
- Analysis of data from the Multiple Risk Factor Intervention Trial (MRFIT) and supporting evidence from other hypertension trials.
- Examination of associations between specific diuretics (hydrochlorothiazide vs. chlorthalidone), CHD mortality, serum potassium levels, and ventricular premature beats.
- Review of clinical studies on left ventricular hypertrophy, ventricular premature beats, and diuretic-induced hypokalemia.
Main Results:
- MRFIT data showed a stronger association between CHD mortality and hydrochlorothiazide compared to chlorthalidone.
- No consistent relationship was found between CHD mortality and diuretic dose, serum potassium, or ventricular premature beats.
- Hypertensive men with left ventricular hypertrophy exhibit increased CHD death risk and ventricular premature beats, irrespective of diuretic therapy.
Conclusions:
- The excess CHD mortality in MRFIT participants with ECG abnormalities may be multifactorial, potentially involving left ventricular hypertrophy, coronary atherosclerosis, and diuretic-induced hypokalemia.
- Hypokalemia, exacerbated by stress and catecholamines, could lower the threshold for ventricular fibrillation in susceptible individuals.
- Further research is crucial to evaluate this potential risk in the large population using diuretic therapy.
Abstract:
The relationship between diuretic therapy and possible increased risk of coronary heart disease (CHD), especially sudden death, is controversial. The initial report from the Multiple Risk Factor Intervention Trial (MRFIT) raised the possibility that the increased CHD mortality observed in a subset of special intervention men with hypertension and certain electrocardiographic abnormalities on their baseline examination might be an unexpected adverse effect of diuretic therapy. Subsequent reports from the MRFIT have revealed a stronger association of CHD mortality to hydrochlorothiazide than to chlorthalidone. There was no consistent relationship of CHD mortality to the dose of either drug, to the most recent serum potassium level, or to the presence of ventricular premature beats. Unfavorable trends of the same magnitude were also seen among similar white men in the Hypertension Detection and Follow-up Program and in the Oslo hypertension trial, although the sample sizes in these two studies were too small to yield clearcut conclusions. Clinical studies have shown an increased risk of CHD death among hypertensive men with left ventricular hypertrophy. Such men are also noted to have a higher frequency of ventricular premature beats, even in the absence of diuretic therapy. Other studies have shown that diuretic-induced hypokalemia is accentuated in the presence of epinephrine and that low potassium levels decrease the threshold for ventricular fibrillation. Thus, although the evidence is still incomplete, it is possible that the excess CHD mortality among MRFIT special intervention men with electrocardiographic abnormalities may have been caused by a combination of increased left ventricular mass in the presence of coronary atherosclerosis, and hypokalemia caused by good compliance with diuretic therapy and accentuated by stress-induced increases in circulating catecholamines. Given the very large population of patients receiving diuretic therapy, further evaluation of this possibility is important.