About one out of every three Americans has high blood pressure. Over time and without treatment, it can tax the heart and weaken arteries, increasing the risk of heart disease, heart attack, stroke, kidney disease, and blindness.
Following current guidelines, many people with high blood pressure have been aiming for a systolic blood pressure of 140 millimeters of mercury or mm Hg (the top number in a blood pressure reading). For those with risk factors such as diabetes and chronic kidney disease, the target is 130 mm Hg. But early results from a new study sponsored by the National Institutes of Health showed that lowering the target to 120 mm Hg significantly reduced rates of heart disease and the risk of death among people age fifty and older. The trial is known as the Systolic Blood Pressure Intervention Trial (SPRINT) and preliminary results were released in September.
"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 Gary H. Gibbons, M.D., director of the National Heart, Lung, and Blood Institute (NHLBI), a division of the National Institutes of Health and the major funder for the SPRINT trial.
Measuring blood pressure takes into account two pressures and is expressed as systolic over diastolic (e.g., 120/80 mm Hg). Systolic pressure, the one studied in the SPRINT trial, is the force exerted on the blood vessel walls when the heart is pumping blood. Diastolic pressure reflects the force present when the heart relaxes between beats and refills with blood. Multiple readings may be taken on different days and if measurements are consistently high, a diagnosis of high blood pressure (hypertension) is made.
Several classes of drugs are available to treat hypertension and each works differently, targeting a specific aspect of blood pressure regulation. Frequently, people need to take more than one medication to achieve blood pressure control.
The SPRINT trial began six years ago and recruited people over age 50 with systolic blood pressures of 130 to 180 mm Hg and at least one other risk factor for heart disease. Over 9,000 patients from 100 medical centers and clinical practices in the U.S. and Puerto Rico were enrolled, including men and women, members of racial and ethnic minorities, and the elderly (people aged 75 and older).
Participants were divided into two groups. The control group received an average of two different blood pressure medications to achieve a target of less than 140 mm Hg. The second treatment group received an average of three blood pressure medications. Researchers adjusted the amount or type of medications for the second group in order to reach a systolic pressure of 120 mm Hg.
The researchers found that achieving the lower blood pressure level reduced rates of cardiovascular events, such as heart attack, heart failure and stroke, by almost a third and reduced the risk of death by almost 25% among trial participants.
Though these findings from the study are significant, they do not mean that everyone with high blood pressure should adopt the more stringent target. "Our results provide important evidence that treating blood pressure to a lower goal in older or high-risk patients can be beneficial and yield better health results overall," said Lawrence Fine, M.D., chief, Clinical Applications and Prevention Branch at NHLBI. "But patients should talk to their doctor to determine whether this lower goal is best for their individual care."