A thorough look at the medical evidence suggests people who’ve had a stroke or a heart attack might benefit from taking blood pressure medications, even if they don’t have high blood pressure.

Researchers found that for every 1,000 people taking the drugs in clinical trials, on average 15 fewer died from heart disease than when the patients got dummy treatment.

But the new study, published in the Journal of the American Medical Association, can’t tease out why that is, and experts say it’s too soon to change treatment recommendations.

“We are not advocating putting everybody on these drugs,” said Dr. Lydia Bazzano of Tulane University in New Orleans, who led the work.

“There are plenty of well-known side effects,” she added. “That’s why it’s important to go to your doctor and talk about whether the benefits would outweigh the risks for you.”

About a third of adult Americans have high blood pressure, which is a risk factor for heart disease. Heart disease, in turn, is the leading killer worldwide and causes about a third of all deaths in the U.S.

Guidelines currently advise lifestyle changes such as losing weight and cutting back on salt for people with high blood pressure. If that doesn’t work, doctors may try drugs such as diuretics ("water pills"), beta blockers or ACE inhibitors.

What is still a matter of debate, however, is whether these drugs also benefit people whose blood pressure hasn’t reached the cut-off point of 140 over 90.

Bazzano’s team pooled 25 earlier studies which included more than 64,000 patients with a history of stroke, heart attack or heart failure, but without high blood pressure.

Study participants were in their 50s or 60s and were followed for about five years at the most. They received either a blood pressure medication—for instance, beta blockers, ACE inhibitors, or calcium channel blockers—or a dummy pill.

Across the board, the drugs were linked to drops in heart disease and death. For every 1,000 people who took them, for example, there were eight fewer strokes, 13 fewer heart attacks 44 fewer heart failures and 14 fewer deaths overall.

Angela Thompson of Tulane, who also worked on the study, said the new findings show people with heart disease might benefit from blood pressure medications regardless of their blood pressure.

But she stopped short of recommending the drugs before more studies have been done.

“It’s a launching point for further discussion,” she told Reuters Health. “It’s possible that if we are missing a study or two it could change the results.”

The Tulane researchers said blood pressure treatment could cost anywhere between $50 and thousands of dollars annually, depending on the drugs used.

Dr. Franz Messerli, who heads the high blood pressure program at St. Luke’s-Roosevelt Hospital in New York, was critical of the new study.

He said beta blockers and ACE inhibitors are already recommended for people who’ve survived a heart attack or have heart failure—not because they lower blood pressure, but because they protect the heart.

An example of a beta blocker is AstraZeneca’s Tenormin; Pfizer’s Accupril is an ACE inhibitor.

“It seems to me that the authors missed the boat to some extent,” Messerli said. “We don’t need to get the blood pressure involved at all.”

Because the new analysis pools earlier studies of different drugs, it’s unclear what role specific drugs play. Assuming they all work is not warranted, according to Messerli.

“That is speculation that is not substantiated by the data,” he said, adding that the drugs might also cause side effects—a problem the new work did not address.

“Beta blockers are not well tolerated, they cause nightmares, depression, fatigue and sexual dysfunction,” said Messerli. “If you lower blood pressure too much, you risk a substantial increase in heart attacks.”

An editorial in the journal also strikes a cautious note.

“Because many patients could potentially begin taking medications at young ages and for many years to prevent cardiovascular events, even modest costs and adverse effects need to be considered,” write researchers from the Ochsner Institute in New Orleans and the University of Queensland School of Medicine in Brisbane, Australia.

SOURCE: Journal of the American Medical Association/JAMA, online March 1, 2011.