A startling new study shows that lowering blood pressure more — with a target of 120 instead of 140 — can cut deaths by 25 percent.
A third of U.S. adults have high blood pressure so millions could be affected by the findings. But government-funded researchers who ran the study say it's too soon for anyone to change what they are doing just yet.
Nonetheless, the results were so clear they stopped the main part of the study early to announce what they'd found.
"This study provides potentially lifesaving information that will be useful to health care providers as they consider the best treatment options for some of their patients, particularly those over the age of 50," said Dr. Gary Gibbons, director of the National Heart, Lung, and Blood Institute (NHLBI), which sponsored the study.
Right now, people are told to get their blood pressure to 140 or lower. That's the top number in a blood pressure reading, known as systolic blood pressure.
But there's been confusion over whether that's the best level. Starting in 2009, the team studied more than 9,300 men and women 50 and older, of various races, keeping some at the target of 140 and taking the rest lower, to a blood pressure level of 120.
The study's not quite finished but the effects on the heart were strong and clear, they announced. Getting blood pressure to 120 or lower reduced rates of cardiovascular events, such as heart attack, stroke and heart failure by a third. It reduced the deaths from any cause by 25 percent.
"This is huge — I mean, 25 percent less deaths and a third — 33 percent — less heart attacks, strokes and heart failure — that's huge," said Dr. Julia Lewis, a kidney specialist at Vanderbilt University who took part in the study.
"You don't get that (by) lowering cholesterol. You don't get that treating people to prevent heart attacks. This is a big impact," Lewis told NBC News.
"If you had 15 minutes to be with a patient, and you had to pick one thing to do — choosing a target blood pressure in the appropriate patient of 120 mm of mercury systolic would be the thing to do."
The team is still studying the effects of lower blood pressure on dementia, memory loss and kidney function. Other studies have suggested lower blood pressure can help reduce or delay dementia symptoms and boost kidney function.
It took, on average, three drugs to get a patient's blood pressure down to 120 — usually a diuretic, the first-line choice for lowering blood pressure, plus a drug called a calcium channel blocker and one called an ACE inhibitor. There are many choices within these classes of drugs. Each lowers blood pressure by a different mechanism.
Diuretics lower blood pressure by ridding the body of excess water, often making patients urinate more often. Calcium channel blockers such as amlodipine or diltiazem lower blood pressure by relaxing blood vessel walls. Angiotensin-converting enzyme (ACE) inhibitors such as lisinopril open blood vessels by blocking a compound called angiotensin.
Normal blood pressure for adults is defined as a systolic pressure below 120 mmHg and a diastolic (bottom) pressure below 80 mmHg.
People are in the "pre-hypertension" stage with a blood pressure of 120/80. It's considered high blood pressure at 140/90 and stage 2 hypertension at 160/100. Both numbers are important and if either number is in the range of hypertension, even if the other number is lower, doctors get concerned.
"Prehypertension can progress to high blood pressure and should be taken seriously. Over time, consistently high blood pressure weakens and damages your blood vessels, which can lead to complications," NHLBI says.
High blood pressure strains the blood vessels and especially small capillaries, in turn damaging organs including the kidneys, heart and the brain. It causes heart attacks, strokes and heart failure as well as kidney failure and dementia.
Despite their enthusiasm, organizers of the trial say they have no message for the general public yet.
"These findings should not make any patients change their medications without talking to their doctor," said NHLBI's Dr. George Mensah.
Some doctors worry about getting blood pressure too low because there had been worries that too much blood pressure medication can cause memory and balance problems in the elderly. The findings have been mixed on this, however.
Dr. Jackson Wright of Case Western Reserve University, who helped lead the study, said a quarter of the patients were 75 or older. The team is still teasing out adverse events. "A first look indicates that the treatment is extremely well tolerated, but that will be looked at much more closely," Wright told reporters.
The American Heart Association says most people should try to lower blood pressure with lifestyle changes before they try drugs. Just losing weight can do it. So can a diet heavy on the fruits and vegetables and lower in salt.
Exercise helps and at least one study suggests a little sunshine can help, too.
"Very few things we do in medicine have such a large benefit to patients. This study's results are going to affect doctors' care of patients with hypertension — not only in our country, but throughout the world," Lewis said.