'Normal' blood pressure might be too high

A new study of heart disease patients finds that "normal" blood pressure might not be low enough. By reducing their pressure well below the levels suggested by national guidelines, patients had fewer heart attacks, strokes, cardiac arrests, hospitalizations for chest pain, procedures to open blocked coronary arteries and deaths.

In addition, lower blood pressure appeared to slow or stop the growth of the fatty deposits called plaque in the coronary arteries, compared with patients taking a placebo, whose plaque growth continued over the two-year study.

The study, led by Dr. Steven Nissen of the Cleveland Clinic, is being published today in the Journal of the American Medical Association. It found that for every 16 heart disease patients with normal blood pressure given drugs to lower it, one adverse event could be prevented.

Although the study was modest in size, with 1,991 patients, all with normal blood pressure, experts said its surprising result reopened this longstanding question: How low should blood pressure go?

The question takes on urgency because millions of Americans have heart disease severe enough to cause the adverse symptoms.

The patients in the study were at high risk, but their blood pressure was considered so well controlled that researchers had not previously asked what would occur if it went lower. Their starting pressure, he said, "was 10 millimeters lower than anyone has studied." Blood pressure is measured in millimeters of mercury.

National guidelines for most people say systolic pressure, when the heart contracts, should be lower than 140 millimeters. Diastolic pressure, when the heart relaxes between beats, should be lower than 90. When the new study began, its participants averaged 129 over 78.

"If you walked in a doctor's office and your blood pressure was 129 over 78, your doctor would say you have normal blood pressure," Nissen said.

The research was sponsored by Pfizer, which makes a drug in the study, amlodipine, or Norvasc. But the investigators say they, not the company, controlled the data. While Pfizer saw the manuscript before it was submitted, they wrote, "the final decision on content was exclusively retained by the authors."

The investigators and other experts said more research was needed before changing national guidelines.

"It's a brick in the wall that is being built in terms of ever lower targets for blood pressure," said Dr. Jeffrey Cutler, a blood pressure researcher at the National Heart, Lung and Blood Institute.

The findings do not apply to healthy people, for whom the side effects of blood pressure drugs might outweigh any benefits of taking them.