MONDAY, Oct. 31, 2016 (HealthDay News) -- So-called "white coat hypertension" is mostly harmless, but in some older people it may indicate a risk for heart disease, a new study suggests.

White coat hypertension refers to high blood pressure readings in a doctor's office or other medical setting in people who typically have normal blood pressure.

This study included 653 people with white coat hypertension and 653 with normal blood pressure. All of the study volunteers were followed for more than 10 years. During that time, there was no difference in the number of new heart problems in either group for people younger than 60.

However, among 92 people aged 60 and older, there were 18 more new heart problem cases among those with white coat hypertension than in those without, according to researchers, led by Dr. Stanley Franklin from University of California, Irvine.

Franklin's team said the findings support the theory that a small number of patients with white coat hypertension actually have a common condition called isolated systolic hypertension, where the top number in the blood pressure reading (systolic blood pressure) is too high, but the bottom number (the diastolic blood pressure) is normal.

Isolated systolic hypertension can be an indicator of risk for heart disease or stroke, the researchers said.

Multiple blood pressure readings, including readings outside a medical setting, are necessary to accurately identify heart risk, especially in older high-risk patients, the researchers concluded.

The study was published online Oct. 31 in the Journal of the American College of Cardiology.

The study may not have been large or long enough to identify risk in younger patients. So, its conclusions about younger patients may not be accurate, Dr. Giuseppe Mancia and Dr. Guido Grassi wrote in an accompanying editorial in the same issue of the journal. They're professors of medicine at the University of Milano-Bicocca in Milan, Italy.

The editorialists said further research is needed to fully understand white coat hypertension.

More information

Blood Pressure UK has more on white coat hypertension.