For those in the ages 50-75 at a higher than usual risk of cardiovascular disease
without diabetes or history of stroke, it’s probably no longer defencible to be
satisfied with a systolic BP reading just under 140.
By Melissa Healy
Two months ago, US officials crowed that a federally funded study gauging the impact of stricter blood pressure control had produced such dramatic results that they were bringing the clinical trial to an early close.
Last Monday, those dramatic results got medicine’s version of a ticker-tape parade: a research article and not one but three editorials in the New England Journal of Medicine detailed and dissected just how steeply heart disease, strokes and deaths from any cause declined in patients who aimed to get their systolic blood pressure reading to 120 mm of mercury.
The upshot: For people between 50 and 75 who are at higher than usual risk of cardiovascular disease but don’t have diabetes and have not already had a stroke, it’s probably no longer defencible to be satisfied with a systolic blood pressure reading just under 140. (Earlier this year, the American Heart Association and American College of Cardiology set a 140/90 mm reading as the correct goal for most patients under 80 years of age with coronary artery disease.)
But getting all such patients’ systolic blood pressure readings to 120 may not be entirely realistic either, said experts assessing the significance of the study, called SPRINT (Systolic Blood Pressure Intervention Trial).
Many of the 4,678 subjects assigned to shoot for a systolic reading of 120 couldn’t quite make it to that goal, despite an escalation in the number of medications they took and an average increase in such side effects as dizziness, electrolyte abnormalities, and injury to or failure of the kidneys.
Still, the trial’s results suggest the benefits of trying were undeniable.
In a follow-up period of just over three years, people between 50 and 75 who make efforts to get that top reading 20 points below 140 mm of mercury reaped a welter of benefits, researchers revealed: Their likelihood of dying of any cause dropped by 27 percent, and they reduced by roughly 25 percent their likelihood of suffering one of a range of cardiovascular outcomes, including heart attack, stroke, heart failure and acute coronary syndrome.
On average, study physicians had to prescribe 2.8 medications to get a study subject’s systolic blood pressure reading to 121.4. Subjects who were assigned to get their systolic blood pressure reading under 140 took, on average, 1.8 different prescription medications, and their systolic blood pressure reading settled at an average of 136.2.
By a key measure — the “number needed to treat” — of those outcomes made it a pretty easy call to shoot for the lower systolic reading in treating a patient over 50 with high blood pressure.
Study authors reckoned that for every 61 patients medicated to achieve the lower systolic number for just over three years, there would be one less cardiovascular event (a heart attack, stroke, heart failure, acute coronary syndrome or death). For every 90 patients who got the more aggressive treatment, one death from any cause would be averted. To avert a death from cardiovascular causes, 172 patients would need to get the more aggressive treatment for a little over three years.
(To put that number in perspective, it took 83 patients treated with a statin medication for five years to prevent a single death, 39 patients treated with a statin to prevent a single non-fatal heart attack and 125 to prevent a single stroke. Treating 50 people at high risk of cardiovascular disease for a year with clopidogrel, known also as Plavix, has been found to prevent one cardiovascular event. But 333 would have to be treated with Plavix to prevent a single death.)
“This clinical trial will change practice,” wrote four senior NEJM editors, led by Editor in Chief
Dr Jeffrey M Drazen.
But whether physicians should accept a systolic reading of 120 as a rigid and immediate requirement was not so clear.
“In my opinion, the results from SPRINT warrant reducing the treatment goal for systolic blood pressure to less than 130 mm HG” in most hypertensives over 50 with no history of stroke and no diabetes, wrote Dr Aram V Chobanian, a cardiologist, blood pressure researcher and former dean of the Boston University School of Medicine.
Even if the systolic target were reduced to that interim level, wrote Chobanian, a majority of Americans with hypertension would be considered to have “uncontrolled” high blood pressure. And physicians, he added, know all too well that when they must prescribe more than two medications to bring blood pressure under control, patients are less likely to stick to their medication regimen.
The SPRINT study, wrote Vlado Perkovic and Anthony Rodgers in an invited editorial, “redefines blood-pressure target goals and challenges us to improve blood-pressure management.” Despite its name, however, the SPRINT study cannot change treatment overnight, they added.
“Success,” noted Perkovic and Rodgers, both at Australia’s University of Sydney’s George Institute for Global Health, “will require a marathon effort.”
Still to come from the SPRINT trial are findings that will look at the impact of aggressively treating high blood pressure on cognitive outcomes such as dementia. And specialty medical organisations will continue to chew on the SPRINT findings to see how and whether they should amend their targets.
“Certainly there will be more to come from guidelines committees,” said Dr Jackson T Wright, one of the study’s lead investigators and a hypertension researcher and clinician at Case Western Reserve’s Medical Center. In the meantime, he added, “I would have no difficulty based on this data to urge my patients to have their blood pressure lowered to as close as 120 as possible.” — Los Angeles Times
