Testing both arms for blood pressure instead of just one could save lives. Researchers from Great Britain's University of Exeter found that checking pressure in both arms could spot people at risk of heart disease, even in those who appear healthy.

Researchers analyzed the medical records of more than 3,000 people between the ages of 50 and 70, who had a greater risk of cardiovascular disease, but were otherwise healthy. They found that a difference of only 5 points (5mm Hg) in systolic blood pressure measurements between the two arms doubled the risk of dying from heart-related disease during the eight-year follow-up.

A discrepancy of at least five points was found in 60 percent of the people in the study. The difference can indicate artery-clogging plaque in the artery on the side of the body with the higher reading.

The plaque indicates peripheral artery disease and boosts the chances that arteries in the heart and brain are also clogged, which increases the risk of heart attack and stroke.

"Current guidelines state that blood pressure should be measured in both arms when assessing patients for hypertension, but often this advice is not followed due to time constraints or lack of awareness amongst clinicians," said Dr. Chris Clark of the University of Exeter Medical School.

"For accuracy, to overcome natural blood pressure fluctuations, it is important to test both arms simultaneously to confirm any difference," he said.

Once diagnosed, people at risk could be advised on lifestyle changes that could lower their risk.

Dr. Christopher O'Donnell of Harvard Medical School says that while most cardiologists routinely measure blood pressure in both arms when a patient is initially evaluated, most primary care doctors don't. "A baseline blood pressure measurement in both arms by primary care clinicians may provide additional information about cardiovascular risk prediction," he said.

The study was published in the British Journal of General Practice.