Researchers say people whose systolic blood pressure, the upper number in the reading, is different in their left and right arm may be suffering from a vascular disease that could increase their risk of death.
Experts say the arteries under the collarbone supply blood to the arms, legs, and brain.
Blockage can lead to stroke and other problems, and measuring blood pressure in both arms should be routine.
The study appears in the online edition of the Lancet journal.
