High blood pressure and high CRP escalate cardiovascular risk

American Heart Association
Tuesday, 25 November 2003

High blood pressure and elevated levels of the inflammation marker C-reactive protein (CRP) may work together to increase cardiovascular risk in women, according to a study in today's rapid access issue of Circulation: Journal of the American Heart Association. When levels of both were elevated, the risk of heart attack and stroke increased as much as eight times, researchers found.

"This study provides the first evidence that CRP and blood pressure interact to increase the risk of adverse cardiovascular outcomes," said senior author Paul M. Ridker, M.D., MPH.

The new findings strengthen the evidence that inflammation plays a key role in the development of cardiovascular disease.
"At all levels of blood pressure, the patients with higher CRP readings were at substantially greater risk of future cardiovascular events than patients with lower CRP," said Ridker, professor of medicine at Harvard Medical School and director of the Center for Cardiovascular Disease Prevention at Brigham and Women's Hospital in Boston.

However, the research team could not conclude from its study "whether blood pressure is stimulating heightened inflammation or whether inflammation is occurring before the development of hypertension," he said.

Ridker and his colleagues evaluated data obtained from 15,215 participants in the Women's Health Study (WHS), an ongoing trial of 28,345 women that is testing the efficacy of aspirin and vitamin E in preventing first-time cardiovascular problems. The women's average age was 54 at enrollment.

The WHS participants analyzed in this study had not received hormone replacement therapy. Researchers had records of their blood pressure, CRP levels and body mass index when they entered the WHS.

Among the 15,215 women, 24.9 percent had a history of hypertension at entry, 12.8 percent were receiving treatment for the disorder, 12.2 percent smoked and 3.3 percent had diabetes. High blood pressure, smoking and diabetes are major risk factors for heart disease.

During a median follow-up of 8.1 years, 321 of the women suffered their first cardiovascular event. Thirty-three women died from cardiovascular causes, 97 suffered a nonfatal heart attack, 85 experienced a stroke and 106 had a procedure to restore blood flow to their heart.

For their analysis, the researchers divided the women into five groups according to their blood pressure readings. They also separated them according to whether CRP levels were less than 3 milligrams per liter (mg/L) or 3 mg/L or greater.

The researchers found, as others have, that the higher the blood pressure level, the greater the risk of a cardiovascular event.

They also found that after adjusting for other risk factors, such as smoking and diabetes, CRP levels, on average, increased with each higher stage of blood pressure. For example, the average CRP count was 1.33 mg/L among women with blood pressures less than 120/75 mm Hg, compared to 1.84 mg/L for those with blood pressure readings of 160/95 mm Hg and above. Statistically, that difference was highly significant.

The risk of a heart attack, stroke, or other cardiovascular event was more than eight times greater for women with the highest blood pressure and CRP readings, compared to those in the lowest.

"This finding has particular interest for the prevention of stroke because we have known for a long time that high blood pressure predicts stroke risk," Ridker said. "These data raise the intriguing possibility that lowering blood pressure might also lower CRP levels. If so, we hope this will not only prevent heart attacks but the devastating consequences of stroke."

Co-authors are Gavin J. Blake, M.D., MPH; Nader Rifai, Ph.D. and Julie E. Buring, M.D.

The study was partly funded by the National Heart, Lung, and Blood Institute.

For more information, or to contact American Heart Association, see their website at: www.americanheart.org