The authors found that different blood pressure readings in the two arms were a sign of the narrowing or hardening of a person’s arteries, particularly on one side of the body.

It’s important to take blood pressure in both arms.

Although seemingly minor, a difference of 15 millimeters of mercury or more between systolic readings in the two arms meant the risk of peripheral vascular disease was two and a half times greater and the risk of cerebrovascular disease was 1.6 times higher. It was also associated with a 70 percent greater risk of dying from heart disease. The precise number of the higher or lower systolic reading was less important than the extent of the difference between them. A difference of even 10 millimeters was enough to raise the risk of peripheral vascular disease.