Nighttime blood pressure was associated with a risk of adverse clinical outcomes.
For every 10-mm-Hg increase in nighttime systolic blood pressure, the risk of cardiovascular outcomes was increased 25%.
There has been some suggestion that nighttime blood pressure is the most predictive of cardiovascular events and maybe the best target for antihypertensive therapy.
Nighttime Hypertension at the Risk of MI and Stroke.
Individually, each 10-mm-Hg increase in blood pressure assessed during nighttime, daytime, and clinic was associated with a 25%, 20%, and 11% increased risk of MI and stroke, respectively. However, after adjustment for multiple confounding variables, including age, gender, diabetes, smoking status, and drug treatment, among others, only the nighttime measurement of blood pressure was predictive of MI and stroke.
Future Research
At present, there are ongoing clinical trials testing whether treating nighttime blood pressure reduces cardiovascular events when compared with treating daytime or clinic blood pressure, but as yet the answer to that question is unknown.
It is not yet known why nighttime blood pressure is more predictive of clinical outcomes compared with the other two measurements.
One of the possibilities is that nighttime hypertension is a marker for something else. "For example, usually the blood pressure drops because the sympathetic tone declines at night. But we know that too much sympathetic tone increases stroke and heart-attack risks. So maybe elevated nighttime blood pressure is just a marker for elevated sympathetic tone? Another possibility is that when the vessels dilate at night and patients maintain high blood pressure in the face of dilated nighttime arterioles, it could be they are exposing their brain and heart to an increased blood-pressure load. These are just some of things that might be going on.
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