How much can lower blood pressure reduce health risks?

October 5, 2015

PITTSBURGH ó A dramatically lower systolic blood pressure ó that big number after the blood-pressure cuff has deflated ó may be necessary to reduce risk of cardiovascular and kidney disease and even death.

Current guidelines to keep systolic blood pressure below 140 millimeters of mercury (mm Hg) might need to plummet below 120 to reduce the health risks of hypertension.

Donít panic and donít let your blood pressure spike. Just stay tuned.

"I would say to wait for more information," said Indu Poornima, the Allegheny General Hospital director of nuclear medicine and director of the hospitalís Womenís Heart Center. "But itís always worthwhile to have a discussion with your doctor to see if the patient would benefit with a more aggressive target."

On Sept. 11, the National Heart, Lung, and Blood Institute stopped its Systolic Blood Pressure Intervention Trial, or SPRINT, when results showed that patients maintaining systolic blood-pressure levels below 120 experienced 30 percent fewer cardiovascular events ó heart attacks, heart disease and strokes ó than those following current guidelines of below 140, reporting 25 percent fewer deaths.

The Data and Safety Monitoring Board that monitors such studies recommended the trial be halted. It would be unethical to deny all 9,300 study participants the option of seeking better blood pressure control to reduce health risks.

The NHLBI now is analyzing results before publishing them in a medical journal while continuing part of the study focused on whether elevated blood-pressure levels affect cognitive function in older adults.

"Weíre working hard to finish the paper and submit it to a journal. I donít want to specify a date, but it will be within a few months," said Lawrence Fine, NHLBIís SPRINT project officer. "Once a paper of this kind with these kinds of results is published, Iím sure that any future guideline group will look at it and integrate it with other research into their recommendations for new guidelines.

"Our job is to provide research information to the larger scientific community and health professionals, so when you have a trial like this one thatís completed successfully, we feel we accomplished our mission," he said.

During the study, participants were divided into two groups, one using medications to reach a targeted systolic rate of less than 140, which on average required two hypertension medications. The intensive-treatment group on average received three medications to keep levels below 120.

The trial involved 100 health centers in the United States and Puerto Rico, including a local University of Pittsburgh trial involving 140 patients. SPRINT didnít include patients with diabetes or those whoíve had strokes or polycystic kidney disease because other studies have focused on those populations, with a current blood-pressure target below 130/80.

According to the institute, "high blood pressure, or hypertension, is a leading risk factor for heart disease, stroke, kidney failure, and other health problems"; one in three adult Americans (about 78 million) having the condition. The World Health Organization and other medical organizations say high blood pressure poses the greatest risk for disease and death.

Blood pressure is measured as a ratio of systolic pressure ó the pressure in arteries when the heart beats (or heart muscle contracts) ó over diastolic pressure, which is arterial pressure between heart beats, according to

Thereís evidence, however, that the risk of cardiovascular disease begins rising at 115/80, said Jackson Wright, an Pittsburgh-area native who led one of five research networks in the SPRINT study at the University Hospitals Case Medical Center in Cleveland. He also directs the centerís clinical hypertension program.

"Itís very clear that relaxing treatment for blood pressure control over age 60 no longer is appropriate," Dr. Wright said, noting the average trial participant age was 68, with 28 percent older than 75.

If SPRINT findings hold up, guideline targets should be lowered, he said. "The question obviously is what to do with patients at 120, and at what point do you use aggressive control with medications rather than changes in lifestyle?"

While awaiting study results, Dr. Wright said, "the last thing I want to do is relax blood-pressure control."

SPRINT likewise begs the question of whether patients and doctors should take immediate action to reduce blood pressure or await study details.

"Itís hard to tell other health care providers how they should react, but this will prompt discussion for all patients over 50 with high blood pressure who donít only have hypertension, but a high risk of cardiovascular disease, chronic kidney disease or past cardiovascular events," said Molly B. Conroy, site principal investigator for SPRINT at Pitt, where sheís an associate professor of medicine and epidemiology. "What this will cause me to do with patients with high blood pressure is to make them aware of the new impact treatment can have and start a discussion of whether intensifying medication would be appropriate," she said.

Hypertension drugs ó including ace inhibitors, diuretics, calcium channel blockers and beta blockers ó especially for elderly patients can pose side effects including lightheadedness that boosts the risk of falling. They also can lead to fatigue and drain a person of stamina. Others might cause allergic reactions, while calcium channel blockers can cause ankles to swell, Dr. Conroy said.

The good news is that most of the drugs are available in generic form at reduced costs.

Dr. Poornima at Allegheny General Hospital said trial results donít surprise her. She already has witnessed better results among her own patients at levels below 120/80. While it may be too early to put trial results into action, "it calls attention to goals of blood pressure being lower, and if that is demonstrated in the study, then it would mean changes in blood-pressure management," she said.

Already, she said, sheís more aggressive in younger patients and those at higher risk for cardiovascular or kidney disease, with hopes that trial results will better explain the impacts of tighter control in different age groups and disease levels.

"I was expecting (SPRINT results) would be the case because I always believed you target levels closer to normal," Dr. Poornima said. "Thatís what we should aim for,"



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