"White-coat" hypertension, also known as isolated office hypertension (IOH), is a frequently diagnosed condition characterized by blood pressure readings that are elevated in the doctor's office but are normal during regular daytime activities. There is a general opinion in the medical literature that people with IOH are at lower cardiovascular risk than people with a more sustained elevated blood pressure. However, a recent study published in the Archives of Internal Medicine refutes that hypothesis.

About the study

Researchers from a large Italian medical center enrolled a total of 126 participants into a study with three groups: 42 people with sustained hypertension, 42 people with IOH, and 42 people with normal blood pressure. Group assignments were based on measurements of mean clinic blood pressure taken during two visits to the clinic one week apart. Mean daytime blood pressure was evaluated by a 24-hour portable heart rate monitor that took readings every 15 minutes throughout the 24 hours.

After the measurements had been assessed, the groups were defined as follows:

IO hypertensive: Clinic blood pressure greater than 140/90 with daytime blood pressure of 130/80 or lower

Sustained hypertensive: Clinic blood pressure greater than 140/90 and daytime blood pressure of 140/90 or higher

Normotensive: Clinic blood pressure less than 135/85 with daytime blood pressure of 130/80 or lower

Participants were men and women between 36 and 48 years of age with a body mass index (BMI) between 22.6 and 28, and hypertensive patients had clinic blood pressures repeatedly greater than 140/90. The three groups were matched by age, sex, and BMI and also by clinic blood pressure (IO and sustained hypertensives) and daytime blood pressure (IO hypertensives and normotensives).

None of the participants had ever been treated with medication to lower their blood pressure. They had no history of heart disease, heart failure, heart attack, angina, congenital or valvular heart disease, diabetes, or connective tissue disorders that might cause changes in the structure and function of the left ventricle of the heart. All three groups were of the same socioeconomic status.

After being assigned to a group, all participants underwent echocardiography of the left ventricle. The left ventricle is the largest chamber of the heart and pumps newly oxygenated blood through the aorta. Because enlargement of the left ventricle is an independent risk factor for heart disease, an echocardiogram was used to determine the size, thickness and function of the left ventricle.

The findings

The left ventricle in IO hypertensives was significantly thicker and larger and had a greater degree of dysfunction than measurements taken from normotensives; these characteristics were not as prominent as those seen in the sustained hypertensives. But even though the IO hypertensives had less left ventricular dysfunction than the sustained hypertensives, statistical analysis revealed left ventricular qualities more similar to sustained hypertensives than to normotensives. This could be a risk factor for heart disease. According to the researchers, this supports the hypothesis that "IOH should not be considered as simply a benign condition."

How does this affect you?

These findings are not necessarily consistent with previously published research in this area. In fact, this is thought to be the first study that compares normotensives and sustained hypertensives matched by mean clinic blood pressure and mean daytime blood pressure. Within the practice of cardiology, there is no consensus as to whether IOH should be treated. This study does not settle the argument, but does reinforce the concept of treating hypertension based on increased blood pressure that occurs only within the doctor's office, especially if there is a family history of cardiovascular disease.

An editorial accompanying this article reviews the "clinical dilemma" of whether or not to treat IOH. In the editorial, Dr. Marvin Moser calls for long-term clinical trials to provide a definitive answer. But in the meantime, he argues, if lifestyle interventions are not effective in reducing IOH, patients should be treated with medication because "treatment today is relatively simple, may not be expensive, need not involve frequent procedures, and can be undertaken at low risk to the patient. The possible benefit of long-term treatment seems to outweigh the maximal risk."