Lowering blood pressure with medications can significantly reduce heart-related risks. However, both excessively high and low diastolic blood pressure (DBP) levels can present challenges.
The Importance of Controlling Blood Pressure:
Lowering blood pressure, particularly systolic blood pressure (SBP), has been shown to reduce the risks of heart attacks, strokes, and death. Lowering both SBP and DBP can provide benefits, but the relationship between DBP and health outcomes is more complex.
Understanding Diastolic Blood Pressure (DBP):
Studies from the late 1970s revealed that while reducing SBP continually improves health outcomes, the same might not hold true for DBP. Lowering high DBP (above 90 mm Hg) can decrease health risks. However, if DBP falls too low (below 60 mm Hg), the risk of heart complications rises. There are several potential reasons for this phenomenon:
- Health Conditions: Low DBP might be more common in people with serious health issues like cardiomyopathy or cancer, or for people of advanced age
- Arterial Stiffness: Low DBP may be a marker of increased arterial stiffness and atherosclerosis, indicating worse overall cardiovascular health.
- Coronary Filling Pressures: Very low DBP can reduce the pressure that fills the coronary arteries, potentially leading to inadequate blood flow to the heart.
Challenges in Elderly Patients:
Elderly patients often exhibit isolated systolic hypertension (ISH), characterized by high SBP and normal or low DBP. Treating ISH properly can lower DBP, which may actually increase risk of cardiovascular events when DBP drops below 55 mm Hg. Studies like the Systolic Hypertension in the Elderly Program (SHEP) have highlighted these risks, showing a higher incidence of cardiovascular events when DBP is consistently too low.
Practical Implications:
In practice, while diastolic hypotension (low DBP) is relatively uncommon as a result of antihypertensive therapy, it can still be a concern, particularly in inadequately treated patients or those with specific conditions like ISH in the elderly.
Recommendations:
- Aim to lower SBP to less than 140 mm Hg as recommended by guidelines such as the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.
- Exercise caution if DBP approaches 55-60 mm Hg. This level may be where the risk of adverse events increases.
- Control other heart disease factors like cholesterol, sodium, and dietary fat or atherosclerosis if you have a low DBP
Takeaways
Achieving the right balance in blood pressure management is crucial. While lowering SBP is generally beneficial, excessively low DBP can pose risks, especially in elderly patients. Careful monitoring and comprehensive management are essential to ensure safe and effective blood pressure control.