A difference in systolic blood pressure between arms may indicate an increased risk for cardiovascular events in the future, even if the difference is modest, researchers found in a study published in the March issue of the American Journal of Medicine.

Using data from Framingham Heart Study cohorts, Ido Weinberg, MD, of Massachusetts General Hospital in Boston, and colleagues evaluated interarm systolic blood pressures of 3,390 patients aged 40 years and older who had no history of cardiovascular disease and examined as part of the original study cohort (between 1991 and 1994) and an offspring cohort (between 1995 and 1998). They defined increased interarm pressure difference as 10 mm Hg and followed participants through 2010.

During the follow-up period, a first cardiovascular event occurred in 598 participants (17.6 percent). Of these participants, 26.2 percent had an interarm systolic blood pressure difference.

Compared with participants who had a normal interarm pressure difference, those with elevated differences had higher rates of diabetes mellitus (13.3 percent vs. 7.5 percent), higher systolic blood pressure (136.3 mm Hg vs. 129.3 mm Hg) and higher total cholesterol (212.1 mg/dL vs. 206.5 mg/dL).

After adjusting for cardiovascular risk factors, an interarm blood pressure difference was associated with a significantly higher risk of first-time cardiovascular events (hazard ratio [HR] 1.38). For every standard deviation increase in pressure difference, HR was 1.07. The investigators did not find an association between interarm pressure difference and mortality risk.

While they did not examine the mechanism behind the association, they noted that their findings were consistent with other studies that found a relationship between interarm systolic blood pressure difference and subclavian artery stenosis, which has been linked to an increased risk of cardiovascular events.   

Weinberg and colleagues argued that this measurement could potentially have considerable clinical value as a risk predictor, given that it is easily obtainable and inexpensive.

“[O]ur findings support recommendations for measurement of blood pressure in both arms, both for accurate blood pressure detection and for detection of ISBPD [interarm systolic blood pressure difference].”