SPRINT: Lower Blood Pressure Target May Reduce Mortality, Cardiovascular Events

ORLANDO, Fla. — A lower systolic blood pressure target of less than 120 mm Hg, as compared with the currently recommended 140 mm Hg, was associated with lower rates of mortality and adverse cardiovascular (CV) events in high-risk patients, according to results from the SPRINT trial.

“We’ve known for many years that there’s a strong observational relationship between blood pressure and cardiovascular risk. There’s no threshold to that relationship. High blood pressure is very common, and it’s thought to be the most important cause of death and disability adjusted life-years around the world,” Paul K. Whelton, MB, MD, MSc, of Tulane University School of Public Health and Tropical Medicine, said during a press conference at the American Heart Association Scientific Sessions.

However, more clarification is needed, according to Dr Whelton. He continued, “Any [anti]hypertensive therapy is known for a long time to reduce risk, and the big question that remains for us in practice is how low should we take that blood pressure?” he continued.

In SPRINT (Systolic Blood Pressure Intervention Trial), the results of which were simultaneously published in the New England Journal of Medicine, Dr Whelton and colleagues sought to evaluate the effect of more intensive treatment for hypertension than is currently recommended by most guidelines.

To qualify for inclusion, participants had to be at least 50 years old, have a treated or untreated systolic blood pressure of 130 mm Hg to 180 mm Hg, and at least one other CV risk factor. These included clinical or subclinical cardiovascular disease (CVD), chronic kidney disease (CKD), a Framingham Risk Score of at least 15% for 10-year CVD risk, or age of at least 75 years or older. Patients who had diabetes or a previous stroke were excluded.

A total of 9361 participants were randomly assigned to intensive treatment with a target systolic blood pressure of less than 120 mm Hg or standard treatment with a target of less than 140 mm Hg.

A composite of myocardial infarction, acute coronary syndromes, stroke, heart failure, or CV death served as the primary outcome. Secondary outcomes included individual components of the primary outcome, all-cause mortality, and the composite of primary outcome or all-cause mortality.

The trial was stopped after a median follow-up of 3.26 years, which fell short of the anticipated 4- to 6-year duration, due to the significant benefits observed with intensive treatment, reported Dr Whelton.

After 1 year, systolic blood pressure was about 15 mm Hg lower in the intensive treatment arm vs the standard treatment arm (121.4 mm Hg vs 136.2 mm Hg). At this time, the researchers noted that difference between the intensive and standard treatment arms became progressively more dramatic over time.

About 1 additional antihypertensive drug was required in the intensive treatment arm, noted Dr Whelton.

Results revealed a significantly lower rate of the primary composite outcome in the intensive treatment arm vs the standard treatment arm (1.65% vs 2.19%), with a hazard ratio (HR) of 0.75 with standard treatment (95% CI, 0.64-0.89). Number needed to treat (NNT) to prevent a primary outcome was 61.

The researchers also noted a “very impressive effect” for reduction in all-cause mortality with intensive treatment (HR=0.73; 95% CI, 0.60-0.90; NNT=90), Dr Whelton said.

When looking at prespecified subgroups, including those  older than 75 years, those with CKD, and those with and without CVD, there did not seem to be any statistically significant treatment effect, according to the study data.

In terms of adverse outcomes, the researchers did not observe any significant between-group difference in the composite outcome of a decreased estimated glomerular filtration rate (eGFR) of at least 50% or the development of end-stage renal disease in participants with CKD.

In participants without CKD, however, the threshold was lower, defined as a decrease in eGFR of at least 30% to a value of 60 mL/min/1.73 m², and incidence was higher in the intensive treatment vs the standard treatment arm (1.21% vs 0.35% per year; HR=3.49; 95% CI, 2.44-5.10). The reasons for this finding remains unclear and requires further follow-up, noted Dr Whelton.

Serious adverse event rates, including hypotension, syncope, electrolyte abnormalities, acute kidney injury or failure, but not injurious falls, were higher in the intensive treatment group than in the standard treatment group.

In summary, Dr Whelton highlighted the significant benefits observed with intensive treatment vs standard treatment.

“We saw a rapid reduction and separation in blood pressure between the 2 treatment arms. The trial was stopped early due to benefit. The incidence of the primary outcome was reduced 25% and all-cause mortality, 27%. We did see some adverse events that were more common in the intensively treated group, and we need to follow those. Overall, we deem that the benefits far outweighed the potential for risk,” Dr Whelton concluded.

Look for an upcoming feature on the SPRINT trial on Endocrinology Advisor.

Disclosure: Dr Whelton reports non-financial support from Takeda Pharmaceuticals International Inc, and Arbor Pharmaceuticals LLC, during the conduct of the study. Please see the study for a full list of the researchers’ financial disclosures.

References

1. Whelton PK. LBCT.05 – SPRINT Trial Results: Latest News in Hypertension Management. Presented at the American Heart Association Scientific Sessions; November 7-11, 2015; Orlando, FL.
2. The SPRINT Research Group. A Randomized Trial of Intensive versus Standard Blood-Pressure Control. N Engl J Med. 2015;doi:10.1056/NEJMoa1511939.