Impact of prehypertension on carotid artery intima-media thickening: actual or masked?

BACKGROUND: Recent studies have reported that prehypertension is associated with increased values of common carotid artery intima-media thickness (CCA-IMT). The aim of this study was to assess the impact of daytime ambulatory blood pressure (BP) levels on the association of prehypertension with CCA intima-media thickening in prehypertensive subjects.

METHODS: A total of 807 subjects with office systolic BP<140 and diastolic BP<90mmHg, underwent 24h ambulatory BP (ABP) monitoring and carotid artery ultrasonographic measurements. The study population was divided into 3 groups according to office and daytime ABP levels: (1) normotensives: subjects with office BP<120/80mmHg and daytime ambulatory BP values within the normal range, (2) actual prehypertensives: individuals with office SBP (120-139mmHg) and/or DBP (80-89mmHg) and daytime ambulatory BP values within the normal range and (3) prehypertensives with masked hypertension (MH): patients with office SBP (120-139mmHg) and/or DBP (80-89mmHg) and elevated daytime ambulatory BP values.

RESULTS: Prehypertensive patients with MH had higher (p<0.01) CCA-IMT values (0.712mm; 95%CI: 0.698-0.725) than actual prehypertensives (0.649mm; 95%CI: 0.641-0.656) and normotensives (0.655mm; 95%CI: 0.641-0.670) even after adjustment for baseline characteristics. Normotensives and actual prehypertensives did not differ significantly regarding CCA-IMT values (p>0.05). After adjusting for potential confounders, (including demographic characteristics, vascular risk factors, and office BP) prehypertension with MH was independently (p<0.01) associated with a 0.06mm increment in CCA-IMT (95%CI: 0.03-0.09).

CONCLUSIONS: Patients with office BP levels in the prehypertensive range, who also have elevated daytime ABP levels, had higher CCA-IMT values than patients with prehypertension with normal daytime ABP values and normotensive individuals.