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Goals of antihypertensive therapy. Is there a point beyond which pressure reduction is dangerous?
1Department of Medicine, University of Lund, Malmö General Hospital, Sweden.
Insights
Lowering blood pressure (BP) too much with antihypertensive treatment may increase coronary heart disease risk. Recent trials suggest a J-shaped relationship, necessitating caution to avoid diastolic BP below 85 mm Hg.
Area of Science:
- Cardiology
- Hypertension Research
- Clinical Trials
Background:
- Antihypertensive treatment is assumed to reduce cardiovascular events with lower blood pressure (BP).
- Hypertension involves long-term vascular changes (hypertrophic, atherosclerotic) affecting coronary and peripheral vessels.
- Rapid BP reduction may theoretically compromise diastolic coronary blood flow, potentially leading to myocardial infarction or arrhythmia.
Purpose of the Study:
- To review recent trial results indicating a J-shaped relationship between achieved BP and coronary heart disease (CHD) incidence.
- To discuss interpretational challenges in these findings, including bias and statistical methods.
- To provide guidance on safe BP targets in antihypertensive treatment.
Main Methods:
- Review of recently presented clinical trial results.
- Analysis of potential biases in trial interpretation (e.g., baseline risk, follow-up duration, statistical methods).
- Discussion of the theoretical link between low diastolic BP and adverse cardiac events.
Main Results:
- Several trials suggest a J-shaped relationship between achieved BP and CHD event incidence.
- Evidence supports the hypothesis that low attained BPs are linked to increased CHD risk.
- Interpretational issues in current data require further investigation.
Conclusions:
- While evidence suggests low achieved BP may increase CHD risk, interpretation challenges persist.
- Further analysis of large hypertension trials is needed to clarify this relationship.
- Caution is advised to avoid decreasing diastolic BP below 85 mm Hg until further results are available.
Abstract:
It has been widely assumed that the preventive effect of antihypertensive treatment on cardiovascular events is increased as lower blood pressure (BP) is achieved. This assumption seemed logical in light of the well-known relationship between BP level and future cardiovascular events. Hypertension, however, develops over many years and is associated with both hypertrophic and atherosclerotic changes within the coronary and peripheral vessels. Antihypertensive drugs when instituted will bring down BP and often arterial blood flow within weeks. Coronary blood flow is limited to diastole. Theoretically then, very low diastolic BPs in coronary arteries with hypertrophic and/or atherosclerotic changes might precipitate a chain of events leading to a myocardial infarction and/or a lethal arrhythmia. Recently, results from several trials have been presented indicating a J-shaped relationship between achieved BP level and incidence of coronary heart disease. These trials are reviewed and problems in the interpretation of the findings such as biaz from varying risk at entry, varying follow-up time, and choice of statistical method, are discussed. Although, the burden of evidence strongly supports the hypothesis that low attained BPs are associated with an increased risk of a coronary heart disease event, problems in the interpretation of this evidence call for further analyses of the relationship within the large hypertension trials. Until such results are at hand caution should be to avoid decreasing BP below 85 mm Hg diastolic.