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What You Should Know About High Blood Pressure
Despite a new understanding of the largely preventable disease, deaths from the ‘silent killer’ are steadily climbing
High blood pressure is often called the “silent killer” because its first symptoms are typically serious: a heart attack or stroke. Deaths related to the disease, also called hypertension, are on the rise in the United States at a time when the scientific understanding of the condition — and the very definition of it — is changing dramatically.
Hypertension’s death rate, adjusted for age, increased by 45% from 1999 to 2017, a new study in the Journal of the American Medical Association (JAMA) finds. And total deaths from heart disease, stroke, and diabetes — for which hypertension is a significant risk factor — are rising as the population grows and ages. Collectively, these four so-called cardiometabolic diseases make up the single leading cause of preventable death in this country.
Between 1999 and 2011, advances in diagnosis and treatment contributed to a decline in death rates for cardiometabolic diseases. But they are no longer enough to combat the rise, the researchers say in the new study — arguing that the focus must now shift more to prevention. “Our findings make it clear that we are losing ground in the battle against cardiovascular disease,” says study leader Sadiya Khan, a cardiologist at Northwestern Medicine and assistant professor at Northwestern University Feinberg School of Medicine.
The root causes of high blood pressure, Khan says, are physical inactivity, poor diet, and the obesity epidemic — factors that feed off each other and which have become part of life as we know it in a world of desk jobs, extensive screen time, and junk food diets.
Redefining “high blood pressure”
With hypertension, blood pushes too hard against vessel walls. There are two measures:
Systolic pressure, the upper number, is the peak of blood pressure reached when the heart muscle contracts. It’s a measure of how hard the heart works. As arteries become hardened or constricted, the pressure increases and the heart struggles to nourish the body.
Diastolic pressure, the lower number, is the lowest pressure reached in the arteries as the heart rests between beats. Similarly, a higher diastolic reading indicates less efficient arteries.
In 2017, the American College of Cardiology and the American Heart Association announced new, lower numbers for the hypertension threshold: 130/80 versus the previous minimum of 140/90. In other words, the new guidelines put you in the high blood pressure category if your numbers are 130/80 and higher. The shift, based on a review of hundreds of studies and clinical trials, was profound, resulting in nearly half the country being put on watch. The number of U.S. adults with high blood pressure instantly jumped from 32% to 46%.
Another important shift in thinking occurred last year.
Health experts had long thought that it was normal for blood pressure to rise as a person ages. But a study in JAMA, drawing from data on 1,252 people who’d had their blood pressure checked every two years from 1948 to 2005, found that regardless of age, blood pressure tends to be stable, unless the top number creeps up to around 120 to 125. At that apparent threshold, some sort of “vascular remodeling” seems to happen, says the study’s senior author, Susan Cheng, a physician in the division of cardiovascular medicine at Brigham and Women’s Hospital.
The arteries adapt until they “may eventually reach a point at which they give way to the pressures, the arterial walls stiffen in their efforts to compensate, a tipping point is reached, and blood pressure starts to rise,” Cheng explains. The rise can then be rapid, the study found, to 140/90 and beyond. And the rate of rise is the same for everyone, regardless of how old they are when they reach the tipping point.
Cheng attributes the rapid rise to the same old things: poor diet, lack of physical activity, and the everyday stresses of modern life. She notes that in remote tribes in the Amazon, where people live without any of these risk factors, blood pressures remain mostly low and stable as people age.
The earlier a person’s rising blood pressure is noticed and addressed, “the more reversible it may be,” Cheng says, stressing however that this possibility hasn’t been proven yet by research.
Both numbers matter now
Meanwhile, health care professionals have long told people to be concerned mostly with the upper blood-pressure number. You can now worry about both.
In what’s billed as the largest study of its kind, researchers recently examined more than 36 million blood-pressure readings from 1.3 million people, along with their health outcomes over time, detailing the results in July in the New England Journal of Medicine. Each measurement, when higher, predicts an increased risk of heart attack or stroke, the researchers say.
Lead author Alexander Flint, a stroke specialist and adjunct researcher at Kaiser Permanente, gives this example from the results: A modestly elevated systolic measurement of 136 conveys an additional 1.9% risk of heart attack or stroke. A similarly modest elevated diastolic reading of 81 also conveys an additional 1.9% risk. A blood pressure of 160/96 packs increased risks of 4.8% and 3.6%, respectively.
These risks might seem small, but that’s because they were calculated only for the general adult population. Among older people or people who smoke or have diabetes along with high blood pressure, “the risks caused by hypertension are much higher,” the study found. Broadly, other research reveals that for every 20 points of systolic pressure increase or 10 points of diastolic pressure increase, the risk of death from heart disease and stroke doubles.
“The take-home message is that both blood pressure numbers — both the top [systolic] and bottom [diastolic] values — matter when it comes to diagnosing and treating hypertension,” Flint says.
What you can do
Experts at Harvard, the Mayo Clinic, and elsewhere offer much the same advice for preventing or treating high blood pressure: engage in moderate physical activity, eat lots of fruits and vegetables, maintain a healthy weight, cut down on salt and booze, avoid processed meat, and don’t smoke.
“We can’t feel high blood pressure, so we need to get our blood pressure measured periodically in order to determine our risks.”
Deep breathing and other relaxation techniques have been shown to lower blood pressure, too. A set of studies earlier this year suggests a daily cup (eight ounces) of blueberries can help lower blood pressure and improve heart health. Flint suggests something else:
“There are no valuable generalizations about which specific medications or interventions are best for managing hypertension,” he says. “The single most important thing that a person with high blood pressure can do is to have an ongoing therapeutic relationship with a primary care provider.”
Treatment must be individualized, Flint says.
“Of all of the factors assessed in general physical exam, particularly in a routine screening visit in an otherwise healthy person, blood pressure is one of the most important data points,” he says. “We can’t feel high blood pressure, so we need to get our blood pressure measured periodically in order to determine our risks.” And the risks of hypertension “can be managed over time with medications and other interventions,” he said.