Even normotensive people can reduce risks

Patients with heart disease or who are at risk of disease lower that chance if they are treated for high blood pressure — even if that blood pressure is lower than current guidelines, researchers suggested at the virtual meeting of the European Society of Cardiology.

In a meta-analysis of 48 clinical trials that represented more than 300,000 patients, researchers for the Blood Pressure Lowering Treatment Trialists Collaboration (BPLTTC) determined that, across the board of baseline systolic blood pressure measurements, pharmaceutical therapy:

  • Reduced the risk of major cardiovascular events by 10% for each 5 mmHg drop in blood pressure over about a 4-year follow-up period.
  • Reduced the risk of stroke by 13%.
  • Reduced the risk of heart failure by 14%.
  • Reduced the risk of ischemic heart disease by 7%.
  • Reduced the risk of cardiovascular death by 5%.

Overall, the researchers reported that for each 5 mmHg reduction in systolic blood pressure, there was an 11% relative risk reduction in the risk of experiencing the composite cardiovascular event endpoint [HR 0.89(95% CI 0.86-0.920] among individuals who did not have documented cardiovascular disease at baseline.

And, in patients with cardiovascular disease, for every 5 mmHg lowering of blood pressure achieved, the risk of an event decreased by 9% [HR 0.91 (95% CI 0.89-0.94), said Kazem Rahimi, MD, deputy director of the George Centre for Healthcare Innovation and associate professor of cardiovascular medicine at Oxford University in the U.K. Rahimi reported the findings at a Hot Line session on August 31, 2020.

At a virtual press conference, Rahimi said that the significant association between blood pressure reduction persisted across all subgroups that made up the composite endpoint — major cardiovascular events or non-fatal stroke; fatal or non-fatal myocardial infarction or ischemic heart disease; or heart failure causing death or requiring hospitalization.

The benefit of blood pressure lowering was also seen across all the different levels of blood pressure measured — including a reduction in events in those individuals with a systolic blood pressure less than 120 mmHg in patients with no known cardiovascular disease at baseline as well as those with cardiovascular disease whose blood pressure was controlled at less than 120 mmHg at the start of the trial.

“We think our findings have major implications for clinical practice,” he said. He suggested that relying on previous cardiovascular disease or blood pressure levels as the key points in making a decision about prescribing blood pressure medication should be reconsidered. He also suggested that the finding should result in simplification of guidelines.

“However,” he said, “we should not draw the conclusion that everyone with heart disease risk factors should be on blood pressure medication. There are other reasons why medication should or should not be prescribed, including the person’s age and risks. There are also economic decisions about when the threshold of treatment should be initiated. There also potential harms and inconveniences involved with therapy.”

In commenting on the study, Robert Carey, MD, professor of medicine at the University of Virginia School of Medicine, Charlottesville, said, “The cardiovascular disease benefit from progressive 5 mm Hg decrements in systolic blood pressure is similar to that reported in several meta-analyses of randomized clinical trials in hypertensive patients.

“Whether the results of the BPLTTC study will change clinical practice depends on further analysis, especially from randomized clinical trials specifically addressing the efficacy and safety of treating normotensive individuals at various levels of cardiovascular disease risk with antihypertensive medication,” Carey told BreakingMED.

“At this time, only adults with hypertension as defined by the 2017 ACC/AHA guideline should be treated with antihypertensive medication, as recommended in the guideline,” he said.

Carey was vice-chair of the 2017 ACC/AHA Clinical Practice Guideline on Hypertension Writing Committee.

Rahimi said the aim of the study was to investigate the impact of blood pressure lowering on various levels of baseline blood pressure among groups of people with known heart disease and among those who had risk factors for heart disease but had not been diagnosed with the disease.

“Pharmacological blood-pressure lowering is known to be an effective strategy for the prevention of cardiovascular disease among people with high or very high blood pressure,” he said. “There is uncertainty around the effects of blood pressure below the typical threshold of a hypertension diagnosis and whether effects differ between those with or without a prior diagnosis of cardiovascular disease.”

The research team combed the medical literature and identified 48 studies that met the inclusion criteria. The studies included 348,854 individuals. The individuals in the studies were stratified by their baseline levels of blood pressure. In the study, 188,583 individuals had no prior cardiovascular disease that had been documented and 160,271 had heart disease at baseline.

The patients were grouped by baseline blood pressure and included about 2% of people in each cohort who had systolic blood pressure below 120 mmHg, and also included a sizable percentage of patients with blood pressure greater than 170 mmHg, including 27% of the patients without documented heart disease and 12.5% of patients who had cardiovascular disease.

About 49% of the population of people without cardiovascular disease in the study were women, but in the group with cardiovascular disease 33% were women. At baseline, the mean systolic blood pressure of those without documented heart disease was 157 mmHg; the mean blood pressure of those with documented heart disease was 146 mmHg. The patients were about 65 years old at baseline and the mean follow-up was about 4 years.

“The study findings are based on a very diverse set of clinical trials,” Rahimi told BreakingMED. “Thus, we can assume the findings to be generalizable to patients similar to those included in those trials.

“The extent to which the findings can be extrapolated to some more underrepresented patient groups for example, very young individuals with low risk of cardiovascular disease or multimorbid patients with low blood pressure, remains uncertain and requires further research,” he said.

  1. Note that the findings in this report should be cautiously interpreted since they are based on a presentation from a scientific congress and have not yet been published in a peer-reviewed journal.

  2. Be aware that current hypertension guidelines recommend limiting the use of antihypertensive drugs to persons with confirmed hypertension.

Samuel Kailes, Contributing Writer, BreakingMED™

The study was funded by the British Heart Foundation, NIHR Oxford Biomedical Research Center, and Oxford Martin School.

Rahimi disclosed relationships with Sensyne Health.

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