High blood pressure in the doctor's office may not predict heart risks

November 24, 2008

Continuously measuring blood pressure may help predict heart disease and related deaths among individuals 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 November 24 issue of Archives of Internal Medicine.

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 antihypertensive drugs, always including a diuretic (medication that increases urine output). Ambulatory blood pressure monitoring, or measuring blood pressure at regular intervals throughout the day, is increasingly important in managing patients with 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, whereas higher average ambulatory blood pressures (both systolic or top-number and diastolic or bottom-number) were associated with the occurrence of fatal and non-fatal heart events. This association remained after controlling for office blood pressure and other risk factors for heart disease. When considered separately, nighttime blood pressure was superior to daytime blood pressure in predicting heart events. If nighttime systolic blood pressure increased by 22 millimeters of mercury, risk for future heart events increased by 38 percent, whereas an increase of 14 millimeters of mercury in diastolic blood pressure increased heart risks by 36 percent.

"This study has important clinical implications," the authors write. "First, it reinforces the importance of ambulatory 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."

Source: JAMA and Archives Journals

Explore further: Breeding a better peanut butter

Related Stories

Breeding a better peanut butter

July 30, 2015

Peanuts are big - big business that is. According to the National Peanut Board, Americans spend about $800 million a year on peanut butter, and peanuts contribute more than $4 billion a year to the US economy.

Aquariums deliver health and wellbeing benefits

July 29, 2015

People who spend time watching aquariums and fish tanks could see improvements in their physical and mental wellbeing, according to new research published in the journal Environment & Behavior.

A Wi-Fi reflector chip to speed up wearables

July 23, 2015

Whether you're tracking your steps, monitoring your health or sending photos from a smart watch, you want the battery life of your wearable device to last as long as possible. If the power necessary to transmit and receive ...

Crushing snakes kill by blood constriction, not suffocation

July 22, 2015

Death by suffocation seems like an awfully protracted way to go and death by suffocation in the grip of a boa constrictor's coils is the stuff of nightmares. Yet Scott Boback from Dickinson College, USA, wasn't so sure that ...

Working out in artificial gravity

July 2, 2015

Astronauts on the International Space Station (ISS) have a number of exercise options, including a mechanical bicycle bolted to the floor, a weightlifting machine strapped to the wall, and a strap-down treadmill. They spend ...

Recommended for you

Machine Translates Thoughts into Speech in Real Time

December 21, 2009

(PhysOrg.com) -- By implanting an electrode into the brain of a person with locked-in syndrome, scientists have demonstrated how to wirelessly transmit neural signals to a speech synthesizer. The "thought-to-speech" process ...

Quantum Theory May Explain Wishful Thinking

April 14, 2009

(PhysOrg.com) -- Humans don’t always make the most rational decisions. As studies have shown, even when logic and reasoning point in one direction, sometimes we chose the opposite route, motivated by personal bias or simply ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.