"If we were to eliminate prehypertension, we could potentially prevent about 47 percent of all heart attacks," said the study's lead author Adnan I. Qureshi, M.D., professor and director of the Cerebrovascular Program in the Zeenat Qureshi Stroke Research Center at the University of Medicine and Dentistry of New Jersey in Newark.
Normal blood pressure is lower than 120/80 millimeters of mercury (mm Hg). Prehypertension is systolic blood pressure between 120 and 139 and/or diastolic pressure between 80 and 89 mm Hg. (Systolic pressure is the force in the arteries when the heart beats and diastolic pressure is the force when the heart is at rest.) Hypertension is blood pressure 140/90 mm Hg or higher.
"There is a gray zone, where you are not hypertensive but your blood pressure is not normal either," he said.
More than a year ago, a national committee coined the term "prehypertension" for this gray area. But until this study, Qureshi said, physicians and the public knew little about what this term meant. About 59 million people in the United States are prehypertensive.
Researchers examined existing data from the Framingham Study and found that a prehypertensive person is more than three times more likely to have a heart attack and 1.7 times more likely to have heart disease than a person with normal blood pressure.
They did not find a significantly increased risk of stroke among those with prehypertension. "This is somewhat surprising, but it may be related to the small number of stroke events in the study," Qureshi said. "The differential effect in this gray zone may be mediated through factors other than blood pressure, such as insulin resistance."
Researchers also investigated the population's attributable risk, which determines how a disease will be impacted if that risk factor were eliminated.
"While we classically recommend lifestyle modifications such as weight control, regular physical activity and changes in diet for people with prehypertension, these findings raise the question of whether we should treat prehypertensive patients more aggressively."
Co-authors are M. Fareed K. Suri, M.D.; Jawad F. Kirmani, M.D.; Afshin A. Divani, Ph.D.; and Yousef Mohammad, M.D. Editor's note: For more information on stroke, visit the American Stroke Association Web site: strokeassociation.org.
Statements and conclusions of study authors that are published in the American Heart Association scientific journals are solely those of the study authors and do not necessarily reflect association policy or position. The American Heart Association makes no representation or warranty as to their accuracy or reliability.