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f you’re at high risk for heart disease and have high blood pressure, you may need to lower your blood pressure even more than your doctor has previously advised to protect yourself from stroke and heart attack.

That’s the key finding from a major trial called SPRINT, funded by the National Institutes of Health. The results were presented today at the annual American Heart Association meeting in Orlando, Fla., and published simultaneously in the New England Journal of Medicine.

There are two measures of blood pressure. Systolic blood pressure is the pressure in the arteries when the heart is contracting; diastolic is the pressure when the heart is relaxing. A healthy blood pressure is under 120 systolic and 80 diastolic, usually written as 120/80 millimeters of mercury (mm Hg). Around 80 million Americans have high blood pressure, also known as hypertension.

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SPRINT found that lowering systolic pressure to 120 cut the risk of dying by 27 percent and the risk of serious cardiovascular disease by 25 percent, compared to lowering systolic pressure to 140. The trial included more than 9,000 men and women age 50 and older with high blood pressure. It was stopped early when the benefits of the lower target became clear.

I talked with Dr. Gail K. Adler, chief of the cardiovascular endocrinology section at Brigham and Women’s Hospital and associate professor of medicine at Harvard Medical School, about her take on the study:

Are the findings from this trial important?

This was a very carefully designed and conducted trial. It will help all physicians better treat high blood pressure and save lives. I think it offers a valuable lesson for patients, too: know your blood pressure, perhaps by checking it at home, and not just learning it once a year at your annual checkup.

How do the SPRINT findings fit in with what’s already known about treating high blood pressure?

We have known for a long time that high blood pressure is bad, and that bringing it down can prevent strokes, heart attacks, and more. Fifty years ago, though, many doctors thought it was it was OK to let older individuals’ blood pressure float on the high side. As more studies included people over 70 and 80, we’ve learned it’s important to lower blood pressure in them, too. SPRINT is adding more nuance to what we know, defining 120 mm Hg as a good target for people over age 50 with cardiovascular disease or at high risk for it.

Does everyone with high blood pressure need to aim for a systolic target of 120?

SPRINT did not include stroke survivors or people with diabetes, so we don’t know if a target blood pressure of 120 is good for them. Also, we do not know if a target of 120 mm Hg is right for frail individuals who are at risk of falls and fainting.

The trial was stopped early. Would we have learned more if it had been allowed to run its course?

The trial was stopped early because the study had answered the question for which it was designed. It wouldn’t have been fair or ethical to keep the better treatment — lowering blood pressure to 120 mm Hg — from the people in the control group. Now that we know the results of the SPRINT trial, we can design new trials to answer new questions.

All medications have unwanted side effects. Does aggressively lowering blood pressure cause problems?

Fainting, which can occur when blood pressure falls too low, was more common in the group of participants aiming for the lower blood pressure. However, falls that led to injury were the same in both groups.

Medications aren’t the only way to lower blood pressure. What role do non-medication strategies play?

There are several ways to help lower blood pressure. Losing weight if needed, cutting back on dietary salt, exercising more, easing stress, and treating sleep apnea will decrease blood pressure in many individuals. Lifestyle changes should accompany medication because they benefit health in more ways than just lowering blood pressure. They can also be useful for preventing blood pressure from climbing in the first place.

Beyond setting the best blood pressure target, what are other areas in which advances need to be made?

There are several different classes of blood pressure medicines, and numerous options in each class. We don’t currently know how to predict which medication works best for an individual. Patients get frustrated that a medicine isn’t working, and may lose confidence in their doctors. Doctors also get frustrated because they cannot predict which medication will work best. Results from SPRINT and other studies underscore the need to better understand which medications work best in which people. We are working to identify gene variations in individuals that nudge them to resist or respond to certain medications. Using genetics to pick the most effective medicine for an individual will let us better treat high blood pressure.

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