High blood pressure is one of the most common health problems worldwide.
It often causes no obvious symptoms, but over time it can damage blood vessels and raise the risk of heart attack, stroke, kidney disease and other serious conditions.
A blood pressure reading contains two numbers.
The top number, called systolic pressure, measures the pressure in the arteries when the heart contracts, while the bottom number, called diastolic pressure, measures the pressure between heartbeats.
Doctors have traditionally considered both numbers when deciding how aggressively to treat high blood pressure. One concern has been that lowering the bottom number too far might reduce blood flow to important organs, particularly the heart.
Research led by Dr. Bill McEvoy and scientists from NUI Galway and other institutions challenged that concern. The study, published in the journal Circulation, analyzed information from more than 47,000 patients around the world.
The researchers wanted to know whether very low diastolic blood pressure becomes dangerous when treatment successfully lowers systolic pressure. Earlier studies had raised concerns about a possible “J-shaped” relationship, in which cardiovascular risk seemed to rise again when diastolic pressure became very low.
However, the researchers found no evidence that lowering diastolic pressure itself caused additional harm. Their results suggested that the systolic number may be the more important target when doctors are treating high blood pressure.
Based on their analysis, the team suggested that systolic blood pressure could be safely lowered into a range of about 100 to 130 mmHg for many patients, even when the diastolic number also falls. This could make treatment decisions simpler in some situations.
The findings are important because systolic blood pressure often rises as people get older. Arteries naturally become stiffer with age, which can push the top number higher even when the bottom number remains normal or becomes relatively low.
Keeping systolic pressure under control can reduce strain on the heart and blood vessels. Large clinical studies have shown that treating high blood pressure can lower the risk of major cardiovascular problems, especially in people who already have a higher risk of heart disease.
The new findings do not mean that the diastolic number should be ignored completely. Blood pressure treatment still needs to be individualized, particularly for older or frail people and for patients who develop dizziness, weakness, fainting or other symptoms when their pressure falls.
People should also not change their blood pressure medicines based on a single reading. Blood pressure naturally changes throughout the day, and doctors often rely on repeated measurements, home monitoring and a person’s overall health when deciding whether treatment should be adjusted.
Lifestyle habits remain an important part of preventing and controlling hypertension. Maintaining a healthy weight, staying physically active and eating a diet rich in vegetables, fruits and whole grains can all support healthier blood pressure.
Reducing excess salt can also help because sodium causes the body to retain water and can increase pressure inside blood vessels. Avoiding smoking and limiting excessive alcohol use can further reduce cardiovascular risk.
Regular blood pressure checks are especially important because hypertension is often called a silent condition. A person may feel perfectly well while high pressure is gradually damaging the heart, brain, kidneys and arteries.
The study adds to a changing understanding of how blood pressure should be treated. Rather than becoming overly concerned when the bottom number falls during treatment, doctors may be able to focus more strongly on achieving a healthy systolic pressure.
For patients, the main message is not to chase a particular number without medical advice. Instead, blood pressure goals should be discussed with a healthcare professional who can consider age, symptoms, medications and the person’s overall risk of heart disease and stroke.
If you care about high blood pressure, please read studies about what to eat and to avoid for high blood pressure, and 12 foods that lower blood pressure.
For more health information, please see recent studies about the connection between potato and high blood pressure, and how to eat your way to healthy blood pressure.
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