Think you have ‘normal’ blood pressure? Ideal doesn't mean risk-free
Even levels of blood pressure that are generally considered "normal" may be high enough to foster the development of heart disease, new research shows.
So you think your blood pressure is normal? Think again.
The latest iteration of an “ideal” blood pressure – a level of 120 millimeters of mercury for systolic pressure, the top number – that Americans are urged to achieve and maintain has been called into question by a long-term multiethnic study of otherwise healthy adults.
The study, published in June in JAMA Cardiology, found that as systolic blood pressure rose above 90 mm, the risk of damage to coronary arteries rose along with it. Systolic blood pressure represents the pressure within arteries when the heart pumps (as opposed to diastolic blood pressure, the lower smaller number, when the heart rests).
The new findings suggest a need to look more carefully at why, despite considerable overall improvements in risk factors for heart disease in recent decades, it remains the nation’s leading killer.
Starting in the 1940s, cardiovascular researchers have unveiled evidence that Americans live in a society that all but guarantees a disproportionately high risk of developing and dying of heart disease. Since my first weeks writing for this newspaper in the early 1960s, I’ve publicised their advice urging people to curb preventable risks to their hearts and blood vessels.
Although significant progress has been made along several fronts, especially drastic cuts in cigarette smoking and lowered levels of artery-damaging cholesterol, atherosclerotic heart disease still kills far too many people in this country long before they reach their potential life span. If not for a plethora of therapeutic advances, like antihypertensive drugs, cholesterol-lowering statins and open-heart surgery to bypass clogged arteries, life expectancy would be a lot worse for many people.
But the overall picture suggests we’ve still got a long way to go. For example, as Americans get fatter and fatter, two major risk factors for heart disease – Type 2 diabetes and high blood pressure – rise along with readings on bathroom scales.
Yes, there are medications to treat both conditions. But why resort to pills, including drugs with unwanted side effects, to modify risks that are within the personal control of most people?
And as shown in the study, even levels of blood pressure that are generally considered “normal” may indeed be high enough to foster the development of atherosclerotic heart disease by more than fourfold above the risk faced by people with systolic blood pressures that are physiologically ideal.
Heart experts have long known that people in traditional nonindustrial societies typically maintain systolic blood pressures in the low 90s throughout life. Unlike typical Americans, their blood pressure does not rise with age.
Rather, it seems, the increase in blood pressure most common among Americans as they age into mid- and late adulthood is an artifact of our sedentary lifestyles and diets too rich in calories and high in sodium, all of which result in stiff, narrowed arteries that result in high blood pressure.
The study, directed by Dr Seamus P. Whelton, cardiologist and epidemiologist at the Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease in Baltimore, followed a cohort of 1,457 middle-aged men and women initially free of atherosclerotic vascular disease and known risk factors for 14.5 years.
As the participants aged, their risk factors for heart disease increased, along with calcium deposits in their coronary arteries and cardiovascular events like heart attacks and strokes.
The research team focused on increases in systolic blood pressure with age, adjusting the data for changes in other heart risks. They found that for every 10mm increase in systolic blood pressure, the risk of calcium deposits and cardiovascular events rose accordingly.
Compared with people with systolic pressures of 90mm to 99mm, those with pressures of 120mm to 129mm were 4.58 times more likely to have experienced a cardiovascular event.
Still, Whelton said in an interview that it would be wrong to focus preventive strategies on blood pressure alone. People with high blood pressure, he said, “are also more likely to have higher cholesterol and blood glucose levels.
The ideal strategy would focus on all risk factors – blood cholesterol, blood sugar and blood pressure. Maintaining a healthful diet, exercising, not smoking and consuming alcohol only in moderation would improve all the risk factors for cardiovascular disease.”
Levels of what doctors consider a healthy systolic blood pressure have been falling for about half a century. In August 1950, a report in JAMA suggested that labeling systolic blood pressures of 140mm, 150mm or 160mm as abnormally high is “arbitrary, particularly when age is concerned.”
The authors suggested that raising acceptable blood pressure levels for people over 40 “would result in a decrease in the reported incidence of hypertension and thus allay some of the widespread and unnecessary fear regarding high blood pressure.”
The latest blood pressure advisory, issued in 2017 by the American Heart Association and American College of Cardiology, considers a systolic blood pressure of 120mm the upper limit of normal, and defines 130mm and above as high blood pressure that warrants treatment with lifestyle measures or medication.
In an editorial accompanying the new study, Dr Daniel Jones, hypertension specialist at the University of Mississippi Medical Center, who helped formulate the current blood pressure guidelines, wrote, “the risk imposed by a blood pressure level below the currently defined hypertensive level is continuous beginning with a systolic blood pressure as low as 90mm mercury.”
Jones said in an interview, “Normal blood pressure can be in the 90s, which is what it is in young healthy women, before the vascular system is damaged by elevated blood pressure over the years. Prevention should start with children, with a healthy diet low in salt and regular exercise, and adults should avoid gaining weight with age, which I realise is very difficult to do in our toxic food society.”
In praising me for maintaining a systolic blood pressure of 100mm to 110mm throughout my adult life, he said, “It’s rare for Americans to reach your age of 79 and not have hypertension”.
When I asked why doctors don’t put more emphasis on maintaining youthful levels of blood pressure, Jones said that in the 1960s medical schools taught that blood pressure should rise with age to assure an adequate blood supply to the brain.
“Only in recent decades has it been accepted that it’s actually better for the brain, kidneys and heart to keep blood pressure down as people age,” he said.
By Jane Brody © The New York Times
This article originally appeared in The New York Times.