Brachial ambulatory blood pressure monitoring (ABPM) provides greater predictive value for cardiovascular (CV) events than clinic blood pressure (BP). However, 24hour ambulatory central BP (central ABPM) may be more closely related to surrogate markers of CV risk than brachial ABPM. The aims of this study were to determine usual values of central ABPM in apparently healthy, unmedicated individuals and to determine whether these relate to two established markers of CV risk, left ventricular (LV) mass and carotid intima-media thickness (cIMT).

24hour brachial and central ABPM was undertaken in 730 healthy individuals aged 18–88 years, using the Mobil-O-Graph device, together with clinic-based measurements of BP. A sub-set of individuals underwent assessment of LV mass (n=356) and cIMT (n=483), by ultrasound.

Central pulse pressure (PP) increased and PP amplification decreased significantly at night (P<0.001 for both). Daytime central, but not brachial, ABPM was significantly and independently associated with cIMT (R²=0.37, P=0.01) and, in general, correlations between central or brachial ABPM parameters and cIMT were stronger in younger (≤50years) than older individuals. The association between 24hour central ABPM and LV mass was of borderline significance (R²=0.16, P=0.05). However, the associations between central or brachial ABPM parameters and LV mass were only significant in older individuals.

The variation in PP amplification within individuals over 24hours, indicates that brachial and central BPs are differentially affected by the activities of daily living. Moreover, central, rather than brachial ABPM is more strongly related to surrogate markers of CV risk.