Preliminary research has found that simply having someone lie down to take their blood pressure could reveal more than expected about their heart health.
Using data from a large, long-term study, researchers found that, compared to readings taken while someone was sitting , readings showing high blood pressure in people who were lying down were better predictors of stroke, serious heart problems, and death. death.
The results were presented at the American Heart Association Hypertension Scientific Sessions in Boston. The work is considered preliminary until full results are published in a peer-reviewed journal.
Dr. Stephen Juraschek, lead researcher on the work, said the findings were surprising and suggest that having people lie down to measure their blood pressure could help identify people who need treatment despite seemingly normal readings taken while lying down. They are sitting.
It has long been understood that controlling high blood pressure or hypertension is an essential part of heart health. But getting an accurate reading while sitting can be tricky, said Juraschek, a general internist at Beth Israel Deaconess Medical Center in Boston and an associate professor at Harvard Medical School.
As defined by the AHA and the American College of Cardiology, normal blood pressure for adults measured in the sitting position is a systolic reading of less than 120 mmHg and a diastolic reading of less than 80 mmHg. However, the readings fluctuate throughout the day.
Juraschek said the "gold standard" for accuracy is ambulatory blood pressure, which takes readings throughout the day. But that requires wearing a monitor for 24 hours.
Over the years, he said, research has shown "time and time again" that nighttime blood pressure measurements are one of the best predictors of cardiovascular disease. But it is difficult to obtain such readings. "It’s not comfortable to have your arm compressed repeatedly throughout the night," she said. "It can affect your sleep."
Juraschek and his colleagues wanted to lay the groundwork for determining whether simply having people lie down in the clinic during the day could identify those at higher risk for cardiovascular disease, similar to blood pressure measurements taken during sleep. They began by comparing readings taken while he was sitting with those taken while he was lying down or supine.
Researchers used data from 11,369 participants in the Community Atherosclerosis Risk Study. Their blood pressure was measured while they were sitting and also when they were lying down.
The average age of the participants was 54 years and they had been followed for a median of 25 to 28 years . People with a history of heart disease, heart failure, or stroke were excluded. More than half of the participants were women and a quarter were black.
The participants were divided into four groups:
- One group had normal blood pressure readings both when sitting and lying down.
- One had high blood pressure only while sitting.
- The third, representing 16% of the participants, had high blood pressure only while lying down.
- The fourth had high blood pressure in both positions.
Over time, the group without high blood pressure in either position had the lowest risk. The group with consistently high blood pressure in both positions was at high risk.
But unexpectedly, Juraschek said, the group that had high blood pressure only while lying down had similar risk levels to those with high readings in both positions, even after taking into account other cardiovascular risk factors.
People with high blood pressure only in the supine position had a 53% increased risk of coronary heart disease, a 51% increased risk of heart failure, a 62% increased risk of stroke, a 78% increased risk of fatal coronary heart disease, and a 34% increased risk of fatal coronary heart disease. % increased risk of death from all causes compared to participants with normal blood pressure in both positions.
The risk of problems predicted by blood pressure in the supine position, "in all cases, was greater than the sitting position, and in many cases it was very close to having an elevation in both," Juraschek said.
The findings imply that checking blood pressure in the supine position could reveal hypertension that would otherwise go undetected in the doctor’s office, he said. But he added that much more research would need to be done first.
Dr. Wanpen Vongpatanasin, a professor of medicine at UT Southwestern Medical Center in Dallas, called the study important but agreed that more research is needed.
Previous work has shown that nighttime blood pressure independently predicts cardiovascular outcomes, but it’s not clear whether that was related to the timing of the readings or the position of the person being measured, said Vongpatanasin, director of the Blood Pressure Fellowship Program. UT Southwestern Hypertension. She was not involved in the new research.
"This study suggests that supine blood pressure may be one explanation, as it has as much impact on long-term cardiovascular outcome as safe sitting blood pressure," he said.
The findings highlight the importance of blood pressure control in all body positions , Vongpatanasin said. But she said it’s too early to make treatment decisions based on supine readings. There are also practical considerations when trying to find time to add such readings into a busy clinical practice, she said.
Juraschek acknowledged that one of the study’s limitations was that, at baseline, patients had been lying down for about 20 minutes , much longer than would happen in a typical doctor’s visit.
But, he said, "I think this is a simple enough assessment that people can be trained to verify it themselves, and they can also use it in screening."
The study was not designed to look for possible explanations for the different readings. Juraschek speculated that several factors could be responsible for these findings, ranging from the possibility that getting an accurate reading is easier when a patient is relaxed and lying down to the physics of how fluids move around the body when it is flat instead of lying flat. sitting.
With more study and more information, supine blood pressure could help detect hypertension in people whose treatment is delayed because they have been "flying under the radar ," he said. It could also identify people who may not need treatment.
But for now, Juraschek said, monitoring blood pressure while sitting will remain key. "There is a wealth of evidence on seated blood pressure treatment that we simply cannot ignore."
