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Experts say the top and bottom numbers on blood pressure are indicators of heart health as well as heart attack and stroke risk. Getty Images
  • Researchers say the top and bottom number are important in blood pressure readings.
  • Both the systolic and diastolic are indicators when it comes to the risk of heart attack and stroke.
  • The new findings don’t significantly change how high blood pressure is treated as medication currently works on lowering both numbers.
  • Experts say the research is a reminder to people to eat healthy, exercise, and limit alcohol as ways to maintain a healthy blood pressure.

If you’ve been told you only have to worry about getting the top number of your blood pressure down, you may want to get a second opinion.

That’s what researchers in a new study are saying.

“The take home message here is that when you’re getting your blood pressure checked, we need to pay attention to both numbers, the systolic and the diastolic,” Dr. Alexander Flint, a stroke specialist at Kaiser Permanente in Northern California and lead author of the study, told Healthline.

The top number, or systolic, reflects how hard your heart is working to pump blood into your arteries. The bottom number, or diastolic, indicates the pressure as your heart relaxes between beats.

Researchers concluded that both numbers were independent predictors of heart attacks and strokes.

“Both the top and the bottom number are strongly linked to outcomes of ischemic stroke, the type of stroke where a blood clot blocks an artery in the brain, as well as hemorrhagic stroke, bleeding in the substance of the brain, and heart attacks,” Flint said.

“This study goes against previous data which shows systolic blood pressure is generally more important,” Ramin Oskoui, a Washington, D.C., cardiologist, told Healthline.

Oskoui is also chief executive officer of Foxhall Cardiology and is affiliated with Sibley Memorial Hospital, Suburban Hospital, and Washington Hospital Center.

In fact, Flint says the findings turn upside down decades of commonly held beliefs about blood pressure readings.

“There had been quite a lot of discussion in the medical literature about this idea that systolic blood pressure was so much more important than diastolic blood pressure, based on previous studies. That perhaps we don’t have to pay attention to diastolic blood pressure. And if that were true, it might present an opportunity to simplify therapy. Let’s only talk about the one number,” Flint explained.

“Here the data are telling us that if we were to ignore the diastolic blood pressure, that would be to the detriment of our patient’s care,” he added.

This study is being called the largest of its kind.

Between 2007 and 2016, the research team analyzed 36 million outpatient blood pressure readings from more than 1 million adult members of Kaiser Permanente in Northern California.

They concluded that while systolic blood pressure had a greater impact, both systolic and diastolic pressures influenced your risk factors.

That was true whether measured against the older threshold of 140/90 or the newer guideline of 130/80.

Flint said the findings won’t change much when it comes to treating your blood pressure with medications.

“It turns out that the medications do both, so we don’t have to make things more complicated in terms of picking and choosing medications,” Flint said.

“Everybody reacts to the medications in different ways. Really, it’s just a matter of working with your physician to find the right medication, the right dose to achieve both of those numbers. All the classes of anti-hypertensive medications work for both numbers,” he said.

“While these findings may not make much difference in the medications I give my patients, it is an opportunity to reinforce with the lay public that the lower your blood pressure, the lower your risk of heart attack, heart failure, stroke, and kidney disease,” Oskoui said.

“We can remind our patients to cut out alcohol, exercise in moderation, and lose weight. Even a 10 to 15 pound weight loss can mean the difference between medication or not,” Oskoui added.

That advice echoes what the American Heart Association recommends:

  • Eat a well-balanced diet low in salt.
  • Limit your alcohol.
  • Get regular physical activity.
  • Manage your stress.
  • Maintain a healthy weight.
  • Quit smoking.
  • Take your medications as prescribed.
  • Work with your doctor.

“We can look at mortality, we can look at different predictors related to blood pressure, specifically the ‘pulse pressure,’ which is a mathematical subtraction of the systolic and diastolic numbers,” Flint said. “In certain circumstances, it may be an independent predictor that is important, so we’re exploring that.”

Flint says this study was carried out using a big data approach with information from the Kaiser healthcare system.

“We have many, many clinics and all those clinics are putting data into electronic medical records, so we are really able to do analytics like this at a close to population-level,” Flint said.

In the not-too-distant future, he said, researchers may be gathering blood pressure data from noninvasive wearable sensors.

“This is sort of a stepping stone toward that even bigger data approach to learning more about the relationship between blood pressure and other factors and the risk of cardiovascular events. We could hopefully identify people at much finer level who are at risk and tailor medical therapy for them,” Flint added.