White-coat hypertension: not guilty when correctly defined

Abstract

The coexistence of persistently high office blood pressure with normal blood pressujre outside the medical setting is often referred to as 'white-coat', 'office' or 'isolated clinic' hypertension. The definition of normal blood pressure outside the medical setting is controversial. In our experience, not only the prevalence of white-coat hypertension, but also left ventricular mass measured echocardiographically and the prevalence of left ventricular hypertrophy in this condition markedly vary on going from more restrictive (lower) to more liberal (higher) limits of ambulatory blood pressure normalcy over quite a narrow range. In a prospective study, cardiovascular morbidities of healthy normotensive controls and subjects with white-coat hypertension did not differ. A more recent analysis of our database supports the use of qujite a restrictive definition of white-coat hypertension (average daytime blood pressure < 130/80 mmHg) in order to identify the minority of subjects who have a low risk of cardiovascular morbid events during the subsequent years. A recent document published by the American Society of Hypertension suggests that slightly higher upper limits of ambulatory blood pressure normalcy (i.e. average daytime blood pressure < 135 mmHg systolic and 85 mmHg diastolic) should be used. In a follow-up study by our group, 37% of subjects with white-coat hypertension spontaneously evolved into cases of ambulatory hypertension, with accompanying increases in left ventricular mass. In that study, the probability of a subject developing ambulatory hypertension increased with the baseline values of ambulatory blood pressure and it was quite low (20%) for those with daytime blood pressures below 130/80 mmHg. In two recent controlled studies, the rate of development of ambulatory hypertension over time for untreated subjects did not differ between the normotensive control group and the group with white-coat hypertension. A final answer regarding the clinical significance of white-coat hypertension will come from very large surveys of the natural history of this condition in the long term. For now, we suggest a verdict of innocence for white-coat hypertension when low values of daytime ambulatory blood pressure (i.e. < 130/80 mmHg) and absence of organ lesions and other risk factors coexist.