San Francisco, CA - Mildly elevated blood pressure in young adults may increase their risk of developing coronary atherosclerosis decades later, a new study suggests [1]. Writing in the July 15, 2008 issue of the Annals of Internal Medicine, Dr Mark J Pletcher (University of California, San Francisco) and colleagues report that prehypertension is, in fact, not uncommon among men and women in their early 30s or younger and correlates with increased coronary calcium later in life.

Drawing on data collected for the Coronary Artery Risk Development in Young Adults (CARDIA) study, Pletcher et al found that 18% of men and women had prehypertension, defined as systolic BP 120 to 139 mm Hg or diastolic BP 80 to 89 mm Hg. They then calculated cumulative exposure to blood pressure in the prehypertension range from age 20 to 35 in units of mm-Hg-years—a method similar to the way that smoking studies calculate pack-years of tobacco exposure. They found that increasing blood-pressure levels in young adulthood paralleled increasing coronary calcium by the time the men and women were in their 40s and 50s. Whereas people with no cumulative prehypertension exposure (0 mm-Hg-years) before age 35 had low coronary calcium prevalence at the time of their last examination (mean age 44), people with the highest cumulative exposure (>30 mm-Hg-years) had a coronary calcium prevalence of 38%. The association was strongest in people with systolic prehypertension in young adulthood.

"There have been other papers looking at prehypertension in other settings, mostly in older adults, so one thing that's new here is that we're looking at prehypertension in younger adults," Pletcher told heartwire. "Perhaps the more important and subtler issue is that we also adjusted for blood-pressure elevation later in life. The reason that the American Heart Association and the national guidelines say that you are supposed to try to lower your blood pressure is to prevent hypertension. But what we have shown here is that prehypertension itself appears to be potentially harmful. Regardless of what happens after age 35, it's important what your blood pressure is before age 35, too."

Subgroup analyses showed that risk factors for prehypertension in young adulthood included male sex, black race, higher body-mass index, and lower socioeconomic status. "This might explain part of the puzzle as to why people of low socioeconomic status are more likely to have heart disease," Pletcher commented.

While the authors did not specifically look at whether interventions to normalize blood pressure in early adulthood would translate into lower calcium scores or fewer cardiovascular events later on, they argue that their findings clearly link early blood-pressure elevations with later atherosclerotic burden.

According to Pletcher, the study results may be particularly germane for internists and general practitioners, since younger adults may not yet be in contact with cardiologists. But the broader message—to maintain a healthy blood pressure, regardless of age—is something that everyone should be aware of, including writers of national guidelines.

"This adds another reason, and more urgency, to our national guidelines, which do say that people with prehypertension should work on diet, exercise, and lifestyle modifications in order to prevent hypertension," Pletcher observed. "And that statement should probably say, 'in order to optimize blood pressure and prevent heart disease later in life.' "