Patients who reduce their blood pressure well below the recommended level can significantly cut their risk of heart disease and death, says a major US study.

Doctors have long debated how low blood-pressure patients need to go, especially as they get older, so the US National Institutes of Health (NIH) sponsored a nationwide study to test if that’s the best goal, or if aiming lower would either help or harm.

Starting in 2010 more than 9,300 high blood pressure patients were enrolled in the Sprint study, the Systolic Blood Pressure Intervention Trial.

The average age of participants was 68 and a quarter of them were over 75. Half received an average of about two medications with the goal of lowering their systolic pressure below 140. The other half received an average of three medications with the goal of getting below 120.

The more aggressively treated patients saw their risk of death drop by almost 25% compared with the less controlled patients, researchers said. And rates of cardiovascular problems dropped by almost 30% in the better-controlled group.

The benefit was strong enough that the NIH stopped the study a year early.

“This study provides potentially life-saving information,” declared Dr Gary Gibbons, director of National Heart, Lung and Blood Institute (NHLBI).

Normal blood pressure is less than a measurement of 120 over 80. High blood pressure is diagnosed once that measurement reaches or passes 140 over 90. Only about half of diagnosed patients have their blood pressure under control.

Last year an expert panel sparked debate by recommending that the treatment target for patients over 60 be a systolic pressure of 150.

The current treatment guidelines are mixed but generally recommend getting that top number – called the systolic pressure – down to about 140 in generally healthy adults, and to 130 in patients who also have kidney disease or diabetes.

One question is whether older patients need to get their blood pressure as low as middle-aged patients do, or if doing so increases the seniors’ risk of side effects including falls.

Researchers will continue tracking Sprint participants to see if kidney disease, brain function and dementia were affected by more aggressive care.

High blood pressure raises the risk of heart attacks, stroke, kidney failure and other health problems.

Good diets, physical activity and keeping a healthy weight help avoid high blood pressure, and can help to lower it before medications are required or along with them.

Researchers stressed that the results were preliminary they should not alter patient care just yet. But the study may eventually change current treatment guidelines.

“This study certainly supports that lower is better,” said Dr Mark Creager, president of the American Heart Association, who was not involved with the new study.

He called the research a possible roadmap to treatment strategies “that will save a significant amount of lives”.