Ambulatory blood pressure (BP) monitoring has become useful in the diagnosis and management of hypertensive individuals. In addition to 24-hour values, the circadian variation of BP adds prognostic significance in predicting cardiovascular outcome. However, the magnitude of circadian BP patterns in large studies has hardly been noticed. Our aims were to determine the prevalence of circadian BP patterns and to assess clinical conditions associated with the nondipping status in groups of both treated and untreated hypertensive subjects, studied separately. Clinical data and 24-hour ambulatory BP monitoring were obtained from 42 947 hypertensive patients included in the Spanish Society of Hypertension Ambulatory Blood Pressure Monitoring Registry. They were 8384 previously untreated and 34 563 treated hypertensives. Twenty-four-hour ambulatory BP monitoring was performed with an oscillometric device (SpaceLabs 90207). A nondipping pattern was defined when nocturnal systolic BP dip was <10% of daytime systolic BP. The prevalence of nondipping was 41% in the untreated group and 53% in treated patients. In both groups, advanced age, obesity, diabetes mellitus, and overt cardiovascular or renal disease were associated with a blunted nocturnal BP decline ( P <0.001). In treated patients, nondipping was associated with the use of a higher number of antihypertensive drugs but not with the time of the day at which antihypertensive drugs were administered. In conclusion, a blunted nocturnal BP dip (the nondipping pattern) is common in hypertensive patients. A clinical pattern of high cardiovascular risk is associated with nondipping, suggesting that the blunted nocturnal BP dip may be merely a marker of high cardiovascular risk.

We used ambulatory blood pressure monitoring (ABPM) in the assessment of salt sensitivity in 40 essential hypertensive patients, comparing 24-h mean blood pressure during 7 days of low salt (20 mmol NaCl/day) and high salt (260 mmol NaCl/day) intake. Salt sensitivity was diagnosed in 18 essential hypertensive patients (45%), each of them showing a significant increase in mean blood pressure (P < .05) from low to high salt diet. Salt-sensitive patients exhibited a high-salt-dependent increase in all blood pressure parameters including 24-h systolic, mean, diastolic blood pressure, blood pressure load, area under the curve, and awake and asleep blood pressure values. These patients exhibited a nondipper profile on both low-salt and high-salt diets. Salt-resistant patients (55%) showed a decrease in awake, and an increase in asleep blood pressure values after high salt intake, thus tending to flatten the circadian blood pressure profile. We conclude that ABPM is a useful method to assess salt sensitivity. In salt-resistant patients high salt intake induces a significant increase in asleep blood pressure with no significant changes in 24-h blood pressure, promoting a flattened blood pressure curve and tending to transform a dipper into a nondipper profile, which could have important implications in end-organ damage. Am J Hypertens 1995;8: 970–977

The recently released American College of Cardiology (ACC)/American Heart Association (AHA) hypertension guidelines proposed new values for defining hypertension: office blood pressure (BP) ≥130 systolic or ≥80 mm Hg diastolic. Furthermore, BP goals for hypertensive patients under pharmacological treatment have been recommended <130/80 mm Hg. New BP limits for office BP have been extended to define corresponding normal values for ambulatory BP monitoring (ABPM). Values of 125/75 mm Hg, 130/80 mm Hg, and 110/65 mm Hg have been proposed for 24-hour, daytime, and nighttime periods corresponding to the office cut-off of 130/80 mm Hg..