WASHINGTON — The nation’s heart experts tightened the guidelines for high blood pressure Monday, a change that will sharply increase the number of US adults considered hypertensive in the hope that they, and their doctors, will address the deadly condition sooner.
Acting for the first time in 14 years, the American Heart Association and the American College of Cardiology redefined high blood pressure as a reading of 130 over 80, down from 140 over 90.
The change means that 46 percent of US adults, many of them under the age of 45, now will be considered hypertensive. Under the previous guideline, 32 percent of US adults had high blood pressure.
‘‘We’re recognizing that blood pressures that we in the past thought were normal or so-called ‘pre-hypertensive’ actually placed the patient at significant risk for heart disease and death and disability,’’ said Robert M. Carey, cochairman of the group that produced the new report. ‘‘The risk hasn’t changed. What’s changed is our recognition of the risk.’’
But the report’s authors predicted that relatively few of those who fall into the new hypertensive category will need medication.
Rather, they hope, that many found with the early stages of the condition will be able to address it through lifestyle changes such as improving their diet, getting more exercise, consuming less alcohol and sodium, and lowering stress.
The new guidelines will be influential in clinical practice, with most health care providers expected to follow the research-based recommendations from leading voices in cardiovascular medicine.
In addition to tightening the definition of high blood pressure, the new report does away with the old category of ‘‘pre-hypertension,’’ which was defined as a top (systolic) reading of 120 to 139 or a bottom (diastolic) number between 80 and 89.
‘‘An important cornerstone of these new guidelines is a strong emphasis on lifestyle changes as the first line of therapy. There is an opportunity to reduce risk without necessarily imposing medications,’’ said Richard Chazal, the immediate past president of the American College of Cardiology.
Instead, the guidelines create new categories of blood pressure, including ‘‘elevated,’’ ‘‘Stage 1 and 2 hypertension,’’ and ‘‘hypertensive crisis,’’ each characterized by various blood pressure readings. Normal blood pressure still will be considered 120 over 80.
The systolic reading refers to the pressure when the heart contracts and sends blood through the arteries. Diastolic pressure is measured when the heart relaxes between beats.
In 2010, high blood pressure was the leading cause of death worldwide and the second-leading cause of preventable death in the United States, after cigarette smoking. Hypertension leads to cardiovascular disease, strokes, kidney disease, and other maladies that kill millions of Americans every year.
Blood pressure is affected by a wide variety of factors including genetics, age, diet, exercise, stress, and other diseases such as diabetes. Men are more likely to have high blood pressure than women and blacks are more likely than whites. Many people are unaware that they have the condition because there are no symptoms.
Much of the data to support the update came from Systolic Blood Pressure Intervention Trial, a large-scale study of more than 9,000 people sponsored by the National Heart, Lung, and Blood Institute. When the results were first presented in 2015, they shook many assumptions about blood pressure management.
The study showed that bringing blood pressure below 120 versus the recommended 140 to 150 could reduce the risk of heart attack and stroke.
While that research only included people 50 and older and at high risk for heart problems, subsequent studies have shown this benefit appears to extend to younger people as well, said Chazal, who is medical director at the Lee Memorial Health System in Fort Myers, Fla.