Using data from a large, long-term study, researchers have found that measuring blood pressure while lying down could reveal more about heart health than expected.
As reported in a post by the American Heart Association (AHA) on the heart.org portal, the researchers found that, compared to measurements taken while sitting, measurements that showed high blood pressure in people lying down were more likely to have a stroke , serious heart problems and death could be better predicted.
Identify treatment needs
The research director Dr. Stephen Juraschek said the results are surprising and suggest that measuring blood pressure while lying down could potentially help identify people who need treatment despite seemingly normal readings taken while sitting.
One of the best predictors of heart disease
It has long been known that treating high blood pressure is an essential part of maintaining heart health. But getting an accurate measurement from a sitting position can be complicated, said Juraschek, an internist at Beth Israel Deaconess Medical Center in Boston and an associate professor at Harvard Medical School.
According to the doctor, the “gold standard” for accuracy is ambulatory blood pressure, which is measured throughout the day. However, this requires wearing a monitor for 24 hours.
Over the years, research has shown “again and again” that nighttime blood pressure measurements are one of the best predictors of cardiovascular disease. But it is difficult to obtain such measurements.
“It is not pleasant to have your arm repeatedly squeezed overnight,” says Juraschek. “It can affect sleep.”
Data from over 11,000 people
Dr. Juraschek and his colleagues wanted to lay the foundation to find out whether people with a higher risk of cardiovascular disease can be identified when they lie in the clinic during the day, similar to blood pressure measurements while they sleep.
They began by comparing the measurements taken while sitting with those taken while lying down.
The scientists used data from 11,369 participants in the Atherosclerosis Risk in Communities study. Their blood pressure was measured both while sitting and lying down.
The average age of the participants was 54 years and they were followed for an average of 25 to 28 years. Individuals with a history of heart disease, heart failure, or stroke were excluded.
Higher risk of illness and death
The participants were divided into four groups: One group had normal blood pressure values both while sitting and lying down. One had high blood pressure only while sitting. The third – 16% of the participants – only had high blood pressure when lying down. And the fourth had high blood pressure in both positions.
Over time, the group without high blood pressure had the lowest risk of cardiovascular disease in both positions. The group with high blood pressure in both positions was consistently at high risk.
But unexpectedly, Juraschek said, the group that had high blood pressure only while lying down had a similar risk to the group with high levels in both positions, even after accounting for other cardiovascular risk factors.
People whose high blood pressure was only measured in the supine position had a 53% higher risk of coronary heart disease, a 51% higher risk of heart failure, a 62% higher risk of a stroke, and a 78% higher risk of fatal coronary artery disease and a 34% higher risk of death from any cause compared to participants with normal blood pressure in both positions.
More research needed
The results suggest that measuring blood pressure in the supine position could reveal high blood pressure that would otherwise be missed in the doctor’s office, the internist explained. However, much more research still needs to be done.
Dr. Wanpen Vongpatanasin, a professor of medicine at the University of Texas Southwestern Medical Center, called the study important but agreed that more research is needed.
Previous work has shown that nocturnal blood pressure independently predicts cardiovascular outcomes. However, it is unclear whether this is related to the timing of the measurements or the position of the person being measured, said Vongpatanasin, who was not involved in the new research.
“This study suggests that supine blood pressure may be an explanation, as it has as great an impact on long-term cardiovascular outcome as sitting blood pressure.”
More time than with doctor’s visits
The results underscore the importance of controlling blood pressure in all body positions, Vongpatanasin said. However, it is too early to make treatment decisions based on the measurements in the supine position.
There are also practical considerations when trying to find time to add such metrics in a busy clinical practice.
Juraschek admits that one of the limitations of the study is that the patients were lying for about 20 minutes during the first measurement, which is much longer than a typical doctor’s visit.
With further studies and more information, measuring blood pressure in the supine position could help detect high blood pressure in people whose treatment is delayed because they have “flown under the radar,” he said. It could also identify people who may not need treatment.
But for now, monitoring blood pressure while sitting will continue to be crucial, Juraschek said. (ad)