Masked hypertension is office normotension in the presence of ambulatory hypertension, which can be subdivided into isolated daytime, isolated nighttime or day-night hypertension. Up to now, no previous studies contrasted the subtypes of masked hypertension in their associations with target organ damage.Design and Method:
Consecutive untreated patients referred for ambulatory blood pressure (BP) monitoring to our Hypertension Clinic were recruited. Office and ambulatory BP were measured using the Omron 7051 and SpaceLabs 90217 monitors, respectively. The cutoff values for daytime and nighttime hypertension were a BP of ≥ 135/85 mmHg and ≥ 120/70 mmHg, respectively. Measures of target organ damage, including left ventricular mass index (LVMI) by echocardiography, carotid-femoral pulse wave velocity (cfPWV) and urinary albumin-to-creatinine ratio (ACR), were determined.Results:
The 1808 participants (mean age, 51 years; women, 52%) included 580 (30.4%) normotensive subjects, and 672 (37.2%) with masked hypertension, among whom 123 (18%) had isolated daytime hypertension, 78 (12%) isolated nighttime hypertension, and 471 (70%) day-night hypertension. After multivariate adjustment, patients with isolated daytime hypertension (7.9 vs 7.5 m/s, P = 0.003), but not those with isolated nighttime hypertension (7.6 vs 7.5 m/s, P = 0.62), had higher cfPWV than normotensive subjects. While on the contrary, patients with isolated nocturnal hypertension (0.79 vs 0.58 mg/mmol, P = 0.002), but not those with isolated daytime hypertension (0.65 vs 0.58 mg/mmol, P = 0.15), had higher urinary ACR than normotensive subjects. Patients with masked day-night hypertension had consistently higher cfPWV (7.8 vs 7.5 m/s, P < 0.001) and urinary ACR (0.74 vs. 0.58 mg/mmol, P < 0.001) than normotensives. For LVMI, no difference (P = 0.11) between any subtypes of masked hypertension and normotension was observed.Conclusions:
Masked hypertension was prevalent in this untreated outpatient cohort, 70% of which was day-night hypertension. Masked daytime hypertension was associated with arterial stiffness while nighttime hypertension was associated with kidney damage and day-night hypertension with both target organ measures.