If your doctor finds that the blood pressure readings between the two arms are different, you may be at an increased risk of chest pain, heart attack and stroke, a large new study concluded.
The study, which was a re-analysis of data from 24 international studies that included almost 54,000 patients, found that a difference of 10 mmHg or more between the two arms increased the risk of cardiovascular events and death in 10 years. For each grade above 10 mmHg, the risk of angina, heart attack and stroke in the next decade increased by 1%, according to the report published in Hypertension.
“Blood pressure should be measured in both arms during cardiovascular evaluation, not only to identify the arm with the highest reading, but also to identify the additional risk conferred by a difference between the arms,” said the study’s lead author, Dr Chris Clark, senior clinical lecturer in general practice at the Faculty of Medicine and Health, University of Exeter, England.
Based on the new findings, Clark and his colleagues say a difference of more than 10 mmHg between the two arms should be a cause for concern.
“We think the difference we are measuring is caused by changes that lead to hardening of the arteries,” Clark said in an email. “Rigid arteries are associated with cardiovascular events and death.”
While it may seem that lower blood pressure in one arm may be good news, the opposite is true.
“Significant differences in blood pressure between the left and right arms are likely to indicate a narrowing of the main arteries due to atherosclerosis (an accumulation of fats, cholesterol and more in the artery walls),” said study co-author Dr. Mary McDermott , professor at the Feinberg School of Medicine at Northwestern University in Chicago.
“Specifically, the arm with the lowest blood pressure is likely to have blockages in blood flow that cause lower blood pressure,” McDermott said in an email.
To take a closer look at the importance of different readings between the arms, the researchers sifted through the medical literature for studies that included blood pressure measurements from both arms and long-term health outcomes.
Ultimately, they focused on 24 studies that included data from 53,827 patients.
The new study is an “important article,” said Dr. Matthew Muldoon, professor of medicine at the University of Pittsburgh School of Medicine and director of the Hypertension Center at the UPMC Vascular and Heart Institute. “It is the most important article to address the issue of blood pressure arm difference,” said Muldoon, who was not affiliated with the new research.
A limitation of the study is that it did not address blood pressure variability from moment to moment, even in one arm, said Muldoon. “When you measure blood pressure repeatedly, it is not stable,” he added.
Despite this, the study shows that differences in blood pressure between the arms are related to an increased risk of cardiovascular events. And that increased risk may be enough to help doctors convince patients that it is necessary to work on lowering blood pressure.
Although the authors suggest that doctors routinely measure blood pressure in both arms, this is unlikely to happen, since there is already a lot to do with each visit.
One solution could be for patients to measure their blood pressure in both arms on their own.
“I love to involve patients in the treatment of hypertension,” said Muldoon. “Automated handcuffs are not expensive. In some ways, it is more practical to expect patients to do this ”.
The American Heart Association offers some tips on how to get the most accurate blood pressure readings at home:
- Clear your schedule and relax: Do not smoke, drink caffeinated drinks or exercise 30 minutes before measuring your blood pressure and empty your bladder to make sure you have at least five minutes of rest before measuring.
- Your body position is important: Sit with your back straight and supported (a dining room chair would be better than a sofa, for example). Place your feet flat on the floor and don’t cross your legs. Place your arm on a flat surface to support it with your arm at heart level. Make sure that the cuff is directly above the elbow fold.
- The cuff should be directly on your skin: Do not take measurements on your clothes.
- Take measurements at the same time every day: It is best to take readings at around the same time each day, morning or evening.
- Make several measurements and record all results: Each time you take your blood pressure, take two or three readings at one minute intervals. If your monitor has internal memory to store readings, take it with you to a doctor’s appointment.
If your numbers are worrying, talk to your doctor. It is useful to have a record of previous readings for an informed discussion of your risk and the next steps.
