VARIABILITY BETWEEN CURRENT DEFINITIONS OF NORMAL AMBULATORY BLOOD-PRESSURE - IMPLICATIONS IN THE ASSESSMENT OF WHITE COAT HYPERTENSION

The assessment of white coat hypertension is complicated by the lack of generally agreed-on normal limits of ambulatory blood pressure. To assess the influence of four of these limits on the prevalence of white coat hypertension and the corresponding distribution of left ventricular hypertrophy, we performed 24-hour ambulatory blood pressure monitoring and echocardiographic studies in 346 untreated patients with essential hypertension and 47 age-matched normotensive control subjects. The upper limits of normal daytime ambulatory blood pressure were lower using standards drawn from clinically normotensive populations than using standards drawn, partly or entirely, from general populations. The prevalence of white coat hypertension differed markedly using the different standards, being 12.1%, 16.5%, 28.9%, and 53.2% (chi2=346.0, p<0.0001). Left ventricular mass index averaged 77 g/m2 in the control group, 85 g/m2 in the two groups with white coat hypertension defined by using standards drawn from normotensive populations (both comparisons not significant versus control group), and 90 and 98 g/m2 in the two groups with white coat hypertension defined by using the other two standards (both p<0.01 versus control group). The prevalence of echocardiographic left ventricular hypertrophy was 0% in the control group, 2.4% and 3.5% in the two groups with white coat hypertension defined by using standards drawn from normotensive populations, and 9.0% and 14.7% in the other two groups with white coat hypertension (p<0.05 and p<0.01, respectively, versus control group). Late diastolic transmitral peak blood flow velocity and its ratio to early peak blood flow velocity were abnormally increased only in the group with white coat hypertension defined by using standards drawn from general populations. These data indicate that until generally agreed-on criteria or ambulatory blood pressure normalcy are available, it is advisable to rely on conservative values to avoid extending the definition of white coat hypertension to subjects at increased risk of left ventricular hypertrophy.