‘White coat hypertension’ targeted

Treatment recommended when stress of seeing doctor spikes blood pressure

Doctors long have known that for certain patients, the stress of a doctor’s visit can cause a spike in blood pressure — a phenomenon known as “white coat hypertension,” after the doctor’s traditional garb. When those patients are tested at home, their blood pressure is just fine.

Traditionally, doctors have believed that patients with white coat hypertension didn’t need to be treated. But a study published online Monday by researchers at UT Southwestern Medical Center in Dallas found that those patients may have twice the risk of a heart attack, stroke or other cardiovascular event compared to people with normal blood pressure.

“Previous studies on white coat hypertension have shown conflicting results,” said Dr. Wanpen Vongpatanasin, professor of internal medicine at UT Southwestern and senior

author of the study. “Many in the medical community have viewed it as a benign condition. But our research suggests that white coat hypertension is associated with an increase in heart and vascular disease.”

Results of the study take on added significance with the release of another blood pressure study Monday suggesting patients would benefit if doctors used a lower target for ideal blood pressure. About 30 percent of Americans have high blood pressure, although many have never been diagnosed. It is the primary cause or a contributing factor in some 362,000 deaths in the U.S. each year.

Home monitoring

The UT researchers tracked some 3,000 people who had their blood pressure taken both at home and in a doctor’s office from 2000 to 2002 as part of the Dallas Heart Study, following up with them between 2007 and 2009. The study also considered the reverse effect, known as masked hypertension, when patients had normal blood pressure at the doctor’s office but high at home.

The researchers found about 12 percent of the patients had high blood pressure in both settings, 3.3 percent had white coat hypertension and 18 percent had masked hypertension.

Seven years later, about one in 300 patients with normal blood pressure had experienced a cardiovascular event such as a heart attack or stroke. Those events were more frequent among those with any high blood pressure readings — about 1 in 100 for those with white coat or masked hypertension, and 1 in 50 for people with sustained high blood pressure.

After accounting for other risk factors, having either white coat or masked hypertension doubled a patient’s risk of an adverse cardiac event.

“Actually more surprising was that the prevalence of masked hypertension is 18 percent,” Vongpatanasin said. “That’s almost one out of five adults in the community, and they would not know it unless they tested their blood pressure at home.”

Someone might have higher blood pressure at home than in a clinical setting, Vongpatanasin said, due to changes in behaviors in the days leading up to a doctor’s appointment.

“Before you go to the dentist, you brush your teeth a little more,” Vongpatanasin said. “With high blood pressure, it might not be well-controlled because they don’t always eat healthfully or exercise, or take the medicine consistently. But right before the doctor’s appointment, they do (all the right things) and take the medicine regularly so that the doctor thinks everything is fine.”

While white coat hypertension is well-known, it’s unclear why such patients might be at higher risk even when their blood pressures at home seem normal.

“It may tell us something about the reaction of their body to stress, and conceivably, people who have more stress in their lives could sustain higher blood pressures than others,” said Dr. William Zoghbi, director of cardiovascular imaging at the Houston Methodist DeBakey Heart & Vascular Center. “I think the message is clear that home blood pressure monitoring is definitely a worthwhile investment.”

People can lower blood pressure through lifestyle changes such as diet or exercise, reducing alcohol and tobacco use, or taking blood pressure medications. But after lifestyle changes, Zoghbi’s number one recommendation for patients with suspected or diagnosed high blood pressure is to get a blood pressure monitor at home.

“If we don’t measure blood pressure in different situations, at home and otherwise, we’re really completely in the dark as to whether blood pressure control is good ... and what you need to do about it.”

‘Really tricky’

Doctors at Kelsey-Seybold Clinic in Houston started using 24-hour blood pressure monitoring devices in 2012 to get a better idea of which patients needed treatment.

“High blood pressure is a really tricky disease to treat,” said Dr. Jonathan Aliota, a cardiologist with the clinic. “It’s up and down moment to moment during the day. It’s up with salt. It’s up with stress. It’s down with caffeine. It’s down with sleep. … What does that one point in time really mean to you?”

“I think it’s a very strong study, and it does suggest that when you see white coat hypertension, you do need to look one step further,” Aliota said. “You’re getting a signal; the signal is saying the blood pressure is abnormally high. Sure, it may be anxiety, or it could be anxiety on top of an underlying condition that needs to be evaluated.”