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Researchers analyzed blood pressure readings from more than 3,300 people ages 40 and older in Massachusetts. The study looked at only the systolic blood pressure, or the "top" number in a blood pressure reading.
People whose systolic blood pressure readings differed by 10 millimeters of mercury (mm Hg) or more between their right and left arms were 38 percent more likely to have a cardiovascular problem, such as a heart attack
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The findings held even after the researchers took into account factors that might increase a person's risk of heart problems, such as high blood pressure, high cholesterol and diabetes.
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"Blood pressure is easily obtained in an office setting, and our findings support recommendations for measurement of blood pressure in both arms," the researchers wrote in the March issue of the American Journal of Medicine.