Get to the Bottom of Blood Pressure Numbers

Which blood pressure number is more important? Both systolic and diastolic pressures can indicate risk for heart disease. Virtua Cardiologist Troy Randle, DO, explains more.

Updated July 07, 2025

By Troy Randle, DO, Virtua Cardiology

Quick quiz: Which of your blood pressure numbers is more important? If you said the top one, you’d be only partially right.

For years, health care providers placed greater emphasis on the top number, or your systolic blood pressure. But recent studies have confirmed that the bottom number, your diastolic blood pressure, also plays an important role in determining your risk of heart attack and stroke.

Systolic and diastolic pressures are actually independent risk factors for cardiovascular disease. You can still be at risk if your systolic reading is normal but your diastolic is elevated, and vice versa.

What Is Your Blood Pressure?

When the heart beats, it creates pressure that pushes blood through your arteries, veins, and capillaries. This pressure is the result of two forces: the blood pumping out of the heart and into the arteries (systolic pressure), and the heart resting between beats (diastolic pressure).

Your blood pressure fluctuates throughout the day. It is affected by many things, including physical activity, foods, stress, and sleep.

When everything is working well, your blood vessels are constantly adapting to the body’s changing demands. They can become wider or narrower as needed.

This helps keep blood flowing freely, so any increases in blood pressure aren’t too large or long-lasting.

Why Does Your Blood Pressure Increase?

According to American Heart Association guidelines, normal blood pressure is less than 120/80 mmHg. You have hypertension if your systolic pressure is 130 and above, your diastolic pressure is 80 and above, or both.

Causes of high blood pressure include:

Obesity or being overweight
Eating a high-salt, high-fat diet
Lack of physical activity
Tobacco use
Age
Stress
Family history
Excessive alcohol use
Having a condition like diabetes

How Do High Blood Pressure Levels Impact Your Health?

Chronic high systolic and/or diastolic blood pressure increases your risk of having a cardiovascular event such as a heart attack or stroke.

A study of 1.3 million people published in the New England Journal of Medicine found that systolic pressure above 140 increased the risk for heart attack and stroke by 18%. Diastolic pressure over 90 showed a 6% higher risk.

Diastolic blood pressure is an especially important measure in younger people, as their blood vessels should be more flexible. If diastolic blood pressure is elevated during the “relaxed phase” of the cardiac cycle— in between beats—it will go even higher as the heart is pushing blood through the arteries. In addition to heart attack and stroke, high diastolic blood pressure increases your risk for atrial fibrillation and heart failure.

It’s important to closely monitor your systolic and diastolic pressures and to take action when appropriate.