Clinical impact of dipping and nocturnal blood pressure patterns in newly diagnosed, never-treated patients with essential hypertension

Abstract

The significance of nondipping and increased nighttime systolic blood pressure (SBP) in established hypertension is well defined. We investigated whether these factors alone or combined correlate with vascular damage in early-stage hypertension. Newly diagnosed, untreated hypertensives were classified as dippers and nondippers according to ambulatory blood pressure (BP). Twenty-four–hour urinary albumin excretion and markers of arterial stiffness (pulse wave velocity, augmentation index, central and peripheral pulse pressure, central BP) and atherosclerosis (carotid intima-media thickness) were assessed. Serum asymmetric dimethylarginine, an index of endothelial dysfunction, was measured in a study subgroup; 10-year cardiovascular risk was calculated. Among 222 hypertensives, only urinary albumin excretion was increased in nondippers, compared to dippers (P = .026). When dippers were further stratified according to nighttime SBP (<120 or ≥120 mm Hg), the first group demonstrated the lowest levels of office, aortic, 24-hour, daytime and nighttime BP, compared to dippers with elevated nighttime SBP and nondippers. Although vascular measurements and asymmetric dimethylarginine were comparable between these groups, dippers with normal nighttime SBP exhibited the lowest cardiovascular risk score (P = .050). In early-stage hypertension, nondipping was accompanied by microvascular, yet not macrovascular and endothelial dysfunction. Dippers with elevated nighttime SBP appear as a distinct group with increased hemodynamic pressure load and cardiovascular risk.