Nocturnal Nondipping and LV Hypertrophy in Hypertension
Nocturnal Nondipping and LV Hypertrophy in Hypertension
The classification of hypertensive subjects according to circadian blood pressure (BP) variations (i.e., dipping vs nondipping) is a useful means for reliable individual risk stratification and effective therapeutic decision-making. Increasing evidence, although not univocal, suggests that a reduced nocturnal BP fall relates to an excess of cardiovascular complications. The association between nondipping status with left ventricular hypertrophy (LVH) and its therapeutic implications are still debated; in this article we examined the studies published in the last decade on this controversial issue. The studies identified by a PubMed search were eligible for the analysis if they fulfilled the following criteria: full articles in English, published from 1 January 2000 to 31 December 2009, and inclusion of adult or elderly subjects. According to these criteria, 26 studies encompassing 3877 participants have been selected. A total of 17 studies for a total of 2497 subjects were positive for a link between nondipping and LVH, whereas the remaining nine studies were negative. Notably, three studies that accurately defined the nondipping status on the basis of two consistent ambulatory blood pressure monitoring sessions over a short time interval showed a significant association of this pattern with LVH; this suggests that a persisting nondipping pattern is associated with a more pronounced cardiac involvement. Preliminary data support the view that nondipping may be reverted to dipping by chronotherapy and by diuretics in salt-sensitive patients. Whether restoring the normal nocturnal BP dip in hypertensives with LVH regresses cardiac damage at present remains an untested hypothesis.
Ambulatory blood pressure monitoring (ABPM) provides varied information on blood pressure (BP) profiles during daily life, over and beyond 24-h average BP values. Increasing attention has been directed to define the components of clinical relevance in the 24-h profile; in particular, an impressive number of studies have been focused on the clinical implications of day–night BP variations. BP profile has been shown to follow a circadian rhythm, night-time BP values being 10–20% lower than daytime values owing to the reduction in sympathetic tone and the parallel increase in vagal activity accompanying the sleep period. In the large majority of normotensive and hypertensive subjects, the night-time decrease in BP is greater than 10% (so-called dippers), whereas in a minority of cases the BP decrease is blunted or even absent (nondippers). Based on this largely accepted classification, numerous studies have shown that hypertensive subjects with a nocturnal BP fall lower than 10% have more pronounced left ventricular hypertrophy (LVH), abnormalities in carotid structure, renal dysfunction, preclinical cerebrovascular disease and increased likelihood of cardiovascular (CV) events than their counterparts with preserved nocturnal BP fall.
The clinical and prognostic value of the nondipping pattern remains a source of debate as other studies did not report substantial differences in the extent of subclinical organ damage (OD) between dipper and nondipper hypertensives characterized by a similar BP load throughout the 24 h. Moreover, a similar incidence of CV events between dippers and nondippers has been reported in a population-based cohort of elderly men and in uncomplicated Type 2 diabetic patients.
Since a convergent body of evidence underlines the relevance of hypertensive OD as a determinant of CV morbidity and mortality, subclinical alterations in CV structure and function are currently regarded as an intermediate stage in the continuum of CV disease and as a strong predictor of CV risk. Quantitative markers of OD (i.e., increased left ventricular mass [LVM], carotid intima-media thickening, reduced glomerular filtration rate and urinary albumin excretion) have been associated with increased CV events independently from conventional risk factors including office BP.
As investigations assessing subclinical OD and outside clinic BP are increasingly available in the management of hypertensive patients, this article aims to update current knowledge on the relationship between nondipping status and cardiac OD in the setting of arterial hypertension. Available evidence on the prognostic and clinical correlates of the nondipping pattern will also be considered.
Abstract and Introduction
Abstract
The classification of hypertensive subjects according to circadian blood pressure (BP) variations (i.e., dipping vs nondipping) is a useful means for reliable individual risk stratification and effective therapeutic decision-making. Increasing evidence, although not univocal, suggests that a reduced nocturnal BP fall relates to an excess of cardiovascular complications. The association between nondipping status with left ventricular hypertrophy (LVH) and its therapeutic implications are still debated; in this article we examined the studies published in the last decade on this controversial issue. The studies identified by a PubMed search were eligible for the analysis if they fulfilled the following criteria: full articles in English, published from 1 January 2000 to 31 December 2009, and inclusion of adult or elderly subjects. According to these criteria, 26 studies encompassing 3877 participants have been selected. A total of 17 studies for a total of 2497 subjects were positive for a link between nondipping and LVH, whereas the remaining nine studies were negative. Notably, three studies that accurately defined the nondipping status on the basis of two consistent ambulatory blood pressure monitoring sessions over a short time interval showed a significant association of this pattern with LVH; this suggests that a persisting nondipping pattern is associated with a more pronounced cardiac involvement. Preliminary data support the view that nondipping may be reverted to dipping by chronotherapy and by diuretics in salt-sensitive patients. Whether restoring the normal nocturnal BP dip in hypertensives with LVH regresses cardiac damage at present remains an untested hypothesis.
Introduction
Ambulatory blood pressure monitoring (ABPM) provides varied information on blood pressure (BP) profiles during daily life, over and beyond 24-h average BP values. Increasing attention has been directed to define the components of clinical relevance in the 24-h profile; in particular, an impressive number of studies have been focused on the clinical implications of day–night BP variations. BP profile has been shown to follow a circadian rhythm, night-time BP values being 10–20% lower than daytime values owing to the reduction in sympathetic tone and the parallel increase in vagal activity accompanying the sleep period. In the large majority of normotensive and hypertensive subjects, the night-time decrease in BP is greater than 10% (so-called dippers), whereas in a minority of cases the BP decrease is blunted or even absent (nondippers). Based on this largely accepted classification, numerous studies have shown that hypertensive subjects with a nocturnal BP fall lower than 10% have more pronounced left ventricular hypertrophy (LVH), abnormalities in carotid structure, renal dysfunction, preclinical cerebrovascular disease and increased likelihood of cardiovascular (CV) events than their counterparts with preserved nocturnal BP fall.
The clinical and prognostic value of the nondipping pattern remains a source of debate as other studies did not report substantial differences in the extent of subclinical organ damage (OD) between dipper and nondipper hypertensives characterized by a similar BP load throughout the 24 h. Moreover, a similar incidence of CV events between dippers and nondippers has been reported in a population-based cohort of elderly men and in uncomplicated Type 2 diabetic patients.
Since a convergent body of evidence underlines the relevance of hypertensive OD as a determinant of CV morbidity and mortality, subclinical alterations in CV structure and function are currently regarded as an intermediate stage in the continuum of CV disease and as a strong predictor of CV risk. Quantitative markers of OD (i.e., increased left ventricular mass [LVM], carotid intima-media thickening, reduced glomerular filtration rate and urinary albumin excretion) have been associated with increased CV events independently from conventional risk factors including office BP.
As investigations assessing subclinical OD and outside clinic BP are increasingly available in the management of hypertensive patients, this article aims to update current knowledge on the relationship between nondipping status and cardiac OD in the setting of arterial hypertension. Available evidence on the prognostic and clinical correlates of the nondipping pattern will also be considered.
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