Systolic blood pressure – the top number – has long been believed to predict a risk of heart attack or stroke. A new study shows that diastolic pressure – the bottom number – also contributes to this risk.
It will no longer be enough to worry only about high systolic blood pressure (the top number in the blood pressure reading). A high diastolic pressure (the bottom number in the blood pressure reading) is also, and independently, a marker of cardiovascular risk. This is revealed by a study conducted by Kaiser Permanente and published on July 18 in the New England Journal of Medicine.
36 million blood pressure readings
This very large study including more than 36 million blood pressure readings on more than one million people thus goes against decades of research that showed systolic high blood pressure was most likely to cause adverse effects. This has had the effect of focusing risk estimation tools and cardiology guidelines on the upper (systolic) number, with some experts even believing that the lower (diastolic) number could be “reasonably ignored”.
Kaiser Permanente researchers found that although systolic pressure had a greater impact, both systolic and diastolic pressures strongly influenced the risk of heart attack or stroke.
“In all cases, the systolic and diastolic pressures are important”
“This research brings a wealth of data to a fundamental question and provides such a clear answer: in all cases, systolic and diastolic pressures matter,” says lead author Alexander C. Flint.
Systolic pressure measures the force with which the heart pumps blood through the arteries while diastolic pressure indicates the pressure exerted on the arteries when the heart is at rest between beats.
A rationale for new guidelines
Dr. Flint says this finding of similar impacts of the two components of blood pressure on lower-threshold cardiovascular risk of 130/80 provides rationale for recent changes to the American College of Cardiology and American Hearth guidelines. Association that advocates tightening of controlled blood pressure in high-risk patients with hypertension.
.