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The heart in hypertension and arrhythmias
1Institute for Postgraduate Medical Education, Department of Cardiology, Prague, Czechoslovakia.
Insights
Antihypertensive drugs may not reduce ischemic heart disease events due to potential negative metabolic effects like hypokalemia. Left ventricular hypertrophy in hypertensive patients is linked to increased ventricular arrhythmias.
Area of Science:
- Cardiology
- Pharmacology
- Clinical Medicine
Background:
- Antihypertensive therapy effectively reduces stroke and heart failure incidence.
- However, its impact on ischemic heart disease events remains unclear.
- Potential adverse metabolic effects of antihypertensive drugs may explain this discrepancy.
Purpose of the Study:
- To investigate the potential negative metabolic effects of antihypertensive drugs on ischemic heart disease.
- To explore the association between hypokalemia, thiazide diuretics, and cardiac arrhythmias.
- To examine the relationship between left ventricular hypertrophy and ventricular arrhythmias in hypertensive patients.
Main Methods:
- Review of existing literature on antihypertensive treatment and ischemic heart disease.
- Analysis of studies investigating hypokalemia induced by thiazide diuretics and its link to arrhythmias.
- Evaluation of electrocardiographic data from hypertensive patients with and without left ventricular hypertrophy.
Main Results:
- Thiazide diuretics can cause hypokalemia in 20-50% of patients.
- Hypokalemia has been associated with malignant arrhythmias during acute myocardial infarction.
- Hypertensive patients with left ventricular hypertrophy showed significantly more premature ventricular contractions.
Conclusions:
- Negative metabolic effects, such as hypokalemia from thiazide diuretics, may counteract benefits of antihypertensive treatment regarding ischemic heart disease.
- Left ventricular hypertrophy presents an electrophysiologic substrate for increased cardiac morbidity and mortality in hypertensive individuals.
Abstract:
Antihypertensive management reduces the incidence of congestive heart failure, malignant hypertension and stroke; however, the overall incidence of events due to ischemic heart disease was not influenced by antihypertensive treatment. One of the possible explanations might be some negative metabolic effects of antihypertensive drugs. Hypokalemia develops in 20 to 50% patients who receive a thiazide diuretic. An association between hypokalemia and malignant arrhythmias (including ventricular fibrillation), in acute myocardial infarction, has been observed. 24-hour ambulatory electrocardiographic monitoring demonstrated a higher frequency of ventricular ectopic beats in hypertensive patients taking thiazides. There is, however, no convincing evidence of a simple causative relation between ventricular extrasystoles and low concentrations of serum potassium. Hypertensives with left ventricular hypertrophy (ECG criteria) had significantly more premature ventricular contractions than patients with established hypertension without left ventricular hypertrophy or normotensive subjects. These data could provide an electrophysiologic substrate for the epidemiologic findings of increased morbidity and mortality in patients with left ventricular hypertrophy.