WHITE-COAT RESISTANT HYPERTENSION

The aim of this study was to evaluate whether sustained hypertensives with high clinic blood pressure, despite multiple drug treatment, show a true resistant hypertension or a ''white-coat effect,'' and whether the pretreatment white-coat effect is maintained despite pharmacologi cal therapy. The occurrence of resistant hypertension was determined i n 250 consecutive essential hypertensives who had had an ambulatory bl ood pressure monitoring before treatment assignment. Twenty-seven of 2 50 hypertensives with persistently high clinic blood pressure despite 3 months of adequate pharmacological therapy underwent further ambulat ory blood pressure monitoring. Using our internal standards, seven pat ients had a true resistant hypertension whereas 20 subjects showed a l arge white-coat effect (white-coat resistant hypertension), ie, high c linic blood pressure (>140/90) but ''normal'' ambulatory daytime (<139 /90 mm Hg) and 24 h (135/85 mm Hg) blood pressure. Using other cutoff points for ambulatory blood pressure, 134/90 and 135/85 mm Hg for dayt ime blood pressure, 10 and 13 patients, respectively, were reclassifie d as true resistant hypertensives and 17 and 14, respectively, were wh ite-coat resistant hypertensives. Interestingly, in white-coat resista nt hypertensives the large differences between clinic and ambulatory d aytime blood pressure (white-coat effect), recorded before treatment a ssignment, were not affected by drugs and remained constant over time. Left ventricular mass index in white-coat resistant hypertensives was significantly lower than in truly resistant hypertensives, suggesting that prognosis could differ between these groups. In this study, usin g either our internal standards or some other cutoffs report-ed in the literature, the white-coat phenomenon was an important cause of resis tant hypertension. The use of ambulatory blood pressure monitoring in these patients may avoid misdiagnosis of resistant hypertension, unnec essary overtreatment, and expensive procedures to look for possible se condary hypertension. (C) 1997 American Journal of Hypertension, Ltd.