Even high-normal blood pressure is too high
By Ben Harder
High blood pressure is a major risk factor for heart disease, and doctors routinely recommend medication to reduce it. A new finding raises the possibility that people with blood pressure at the high end of what is considered the normal range should receive similar treatment.
Individuals with systolic pressure at or above 140 millimeters of mercury (mmHg) or diastolic blood pressure at or above 90 mmHg are considered to have high blood pressure, also called hypertension. Systolic is the maximum pressure reached with each pulse of blood, and diastolic is the minimum pressure between pulses.
A study published in the Nov. 1 New England Journal of Medicine finds an elevated risk of strokes, heart attacks, and heart failure among patients without hypertension but with systolic blood pressure between 130 and 139 mmHg or diastolic pressure between 85 and 89 mmHg.
The researchers used data from the Framingham (Mass.) Heart Study, which began in 1948 and includes thousands of participants. During initial screening for the Framingham study, researchers had recorded each subject’s blood pressure and other data related to risk of heart disease. They didn’t measure several factors now known to influence heart disease, such as physical activity and blood concentrations of different cholesterols.
A team led by Ramachandran S. Vasan of the Boston University School of Medicine recently analyzed data from 6,859 participants who were free of hypertension and heart disease at the initial screening. Over a follow-up period averaging more than 11 years, the researchers tallied how many subjects had suffered a serious cardiovascular problem. All such events had been recorded for the study, even if they weren’t fatal.
Subjects who initially had high-normal blood pressure were more likely to experience a cardiovascular event during the follow-up than those with blood pressure below 130 mmHg systolic and 85 mmHg diastolic were. For example, women with high-normal blood pressure had more than twice the risk of those with initial pressures below 120 mmHg systolic and 80 mmHg diastolic.
The researchers then analyzed the data using a second statistical method to account for changes in a given individual’s blood pressure over time. Some people in the high-normal category had developed hypertension during the study. Even removing this group from the high-normal category in this analysis, the researchers found that having high-normal blood pressure put people at increased risk for heart disease.
In a commentary accompanying the study, Julio A. Panza of Washington (D.C.) Hospital Center hails the finding as “an important advance in our understanding of the magnitude of the problem” of high blood pressure. He agrees with the researchers that it is now important to determine whether physicians should lower the threshold blood pressures for prescribing antihypertensive medication or recommending lifestyle changes.
