Role of ambulatory blood pressure monitoring in the assessment and prognosis of patients with borderline hypertension

The role of ambulatory blood pressure (ABP) monitoring in the assessment of mild/borderline hypertension (BHT) is unclear. The aim of this study was to test the hypothesis that measurement of ABP in borderline hypertensives differentiates patients with true mild hypertension from those with isolated clinic hypertension (raised office BP but normal ABP) and that a raised ABP identifies a subgroup who are more likely to progress to and require treatment over 1 year. Consecutive untreated patients with BHT (n = 127, 44 +/- 13 years, 45% male) were divided into two groups according to awake ABP: Group 1 (normal ABP < or = 136/86, n = 48), and Group 2 (abnormal ABP > 136/86, n = 79). Left ventricular mass index (LVMI) was greater (116 +/- 30 vs 101 +/- 25 g/m2, p < 0.01) and the proportion of patients with an increased LVMI was significantly higher (34% vs 17%, p = 0.05) in Group 2. During 1 year of follow-up, significantly more patients in Group 2 (34%) required antihypertensive treatment compared with Group 1 (8%, p = 0.01). ABP monitoring usefully discriminates between patients with true BHT and those with isolated clinic hypertension. An elevated awake ABP on initial assessment is associated with a higher LVMI and a greater likelihood of progression to moderate hypertension requiring pharmacological treatment.