PS 05-10 THE CLINICAL CHARACTERISTICS OF MASKED HYPERTENSION

Abstract

Objective: Background: Masked hypertension, defined as a normal blood pressure (BP) in the clinic or office (<140/90 mmHg) but an elevated BP out of the clinic (ambulatory daytime BP or home BP > 135/85 mmHg), is associated with poor cardiovascular prognosis. Aims: We investigated the clinical characteristics of masked hypertension in patients who were treated with anti-hypertensive drugs. Design and Method: We enrolled 347 patients with essential hypertension and divided them into 2 groups on the basis of the difference between their weekly averaged home BP measured in morning right before hospital visit and office BP: (Group M: home BP > office BP, n = 135, and Group O: home BP Results: There were no differences in age, gender, duration of hypertension, number of BP-lowering medications and comorbidities between the two groups. Home BP was higher and office BP was lower in Group M compared with those in Group O (Home BP: 135.4 ± 11.5 / 75.0 ± 10.1 mmHg in Group M and 125.2 ± 9.2 / 71.3 ± 9.1 mmHg in Group O, p < 0.01, and Office BP: 126.0 ± 10.0 / 72.4 ± 9.6 mmHg in Group M and 136.0 ± 10.3 / 77.0 ± 8.6 mmHg in Group O, p < 0.01). Estimated salt intake assessed by urinary sodium excretion from spot samples was greater in Group M than in Group O (9.1 ± 2.9 g/day and 8.3 ± 2.3 g/day, p < 0.01). While plasma aldosterone concentration (PAC) was greater in Group M than in Group O (11.5 ± 4.9 ng/dl and 10.1 ± 4.6 ng/dl, p < 0.05), plasma renin activity (PRA) and PAC/PRA ratio was similar in the two groups. Conclusions: High salt intake and high PAC are associated with elevated home BP in patients with hypertension despite being well-controlled office BP on medications.