High Blood Pressure in the Doctor's Office May Not Predict Heart Risks

CHICAGO -- Do you test your blood pressure at home? Maybe you should. Continuously measuring blood pressure may help predict heart disease among those with treatment-resistant hypertension, while blood pressure readings taken in a medical office do not appear to predict future heart risks, according to a report in Archives of Internal Medicine, one of the JAMA/Archives journals.

About 10 percent to 30 percent of individuals with high blood pressure have a condition known as resistant hypertension, according to background information in the article. For these patients, blood pressure remains high despite treatment with at least three blood pressure medications. Measuring blood pressure at regular intervals throughout the day is increasingly important in managing this condition because of the possibility of a white-coat effect (when an individual only has high blood pressure at the physician's office).

Gil F. Salles, M.D., Ph.D., studied 556 patients with resistant hypertension who attended an outpatient clinic between 1999 and 2004. Participants underwent a clinical examination and had their blood pressure monitored continuously during a 24-hour period (every 15 minutes throughout the day and every 30 minutes at night). They were followed up at least three to four times a year until December 2007.

After a median (midpoint) follow-up period of 4.8 years, 109 (19.6 percent) of participants had a cardiovascular event or died of cardiovascular disease. This included 44 strokes, 21 heart attacks, 10 new cases of heart failure and five sudden deaths. Seventy patients (12.6 percent) died, including 46 (8.3 percent) of cardiovascular causes. Blood pressure measured in the office did not predict any of these events. z"This study has important clinical implications," the authors write. "First, it reinforces the importance of ambulatory [home] blood pressure monitoring performance in resistant hypertensive patients. Furthermore, ambulatory blood pressure monitoring should be performed during the whole 24 hours, with separate analyses of the daytime and nighttime periods, because it seems that nighttime blood pressures are better cardiovascular risk factors than are daytime blood pressures.""Second, it raises the question of whether therapeutic interventions directed specifically at controlling nighttime hypertension will be able to improve cardiovascular prognosis compared with the traditional approach of controlling daytime blood pressure levels," they conclude. "This important clinical question should be addressed in future prospective interventional studies."
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