THURSDAY, Dec. 29 (HealthDay News) -- Because hot weather increases nighttime systolic blood pressure in elderly hypertensives, high blood pressure treatment in such patients may need to be monitored more closely during the summer, according to a study published online Dec. 27 in Hypertension.
Pietro A. Modesti, M.D., Ph.D., of the University of Florence, Italy, and colleagues examined records of 6,404 hospital patients (average age 59) who underwent 24-hour ambulatory blood pressure monitoring (ABPM) between October 1999 and December 2003. They evaluated the impact of air temperature on blood pressure by looking at measurements recorded at weather stations in Florence and Milan.
In patients over age 65 under treatment for hypertension, the researchers found that nighttime systolic blood pressure was significantly higher (134 mm Hg) on hot days than on cold days (129 mm Hg), which may increase the risk of both target organ damage and acute cardiovascular events. They also found that hot and cold weather had no significant effect on nighttime systolic blood pressure in younger subjects or in elderly patients not under treatment for hypertension.
"Our results show for the first time that hot weather is associated with an increase in systolic pressure at night in treated elderly hypertensive subjects," the authors conclude. "This may be because of a nocturnal BP escape from the effects of a lighter summertime drug regimen and may have important implications for seasonal modulation of antihypertensive treatment."
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