High Night Blood Pressure in Treated Hypertensive Patients: Not Harmless

UNLABELLED: The left ventricular mass index (LVMI) is better related to activity than resting systolic blood pressure (BP) in treated hypertensive patients. Many recommend ambulatory BP monitoring only during the day. However, 24-hour BP monitoring may be useful in treated patients to check adequate control of BP during the entire 24-hour period. We tested the influence of night BP on LVMI in treated versus nontreated patients. We compared two groups of hypertensive patients: A: 40 patients who had discontinued therapy at least 8 days prior to the study; B: 24 patients treated for more than 3 months with the same drugs (beta-blockers in 14 cases). Ambulatory BP was recorded every 30 minutes during night and every 15 minutes during day (Spacelabs 5200). The LVMI was calculated from M mode echo blind reading (Devereux's formula). Correlation coefficients between LVMI and casual, systolic BP were calculated for both day (7:00 AM to 10:59 PM) and night time (11:00 PM to 6:59 AM). Day systolic BP is better related to LVMI than casual and night systolic BP in group A. In contrast, a significantly higher correlation existed between night BP and LVMI in B, though average night BP level was lower. CONCLUSION: 24-hour BP monitoring may be useful in treated hypertensive patients. Inadequate lowering of night BP may partially account for persistent LVH in treated hypertensive patients.