Ambulatory blood pressure and urinary albumin excretion in clinically healthy subjects

Average daily blood pressure, not office blood pressure, is associated with progression of cerebrovascular disease and cognitive decline in older people

BACKGROUND

High blood pressure (BP) is a risk factor for cerebrovascular disease, including stroke. Little is known about the importance of BP on the progression of microvascular disease of the brain, which has been associated with functional decline in mobility and cognition in older people.

METHODS AND RESULTS

This was a prospective cohort of subjects 75 to 89 years of age to determine relations among vascular risk factors, white matter hyperintensity volume, and functional status. Ninety-nine subjects were enrolled through the use of a balanced 3×3 matrix stratified by age and mobility performance, and 72 subjects completed all sets of baseline and follow-up studies at 2 years. Subjects were excluded if there were medications or systemic or neurological diseases that could compromise mobility. Ambulatory and clinic BP monitoring, magnetic resonance imaging, gait studies, and neuropsychological testing were performed at baseline and after 24 months. Brain classification into normal white matter and T2-hyperintense white matter hyperintensity volume was performed with semiautomated segmentation. Quantitative measures of mobility and cognitive function were obtained longitudinally. Increased ambulatory systolic BP, but not clinic systolic BP, from baseline to 24 month follow-up was associated with increased white matter hyperintensity volume over that same period, as well as measures of executive function/processing speed. Similar associations were observed for 24-hour BP, awake BP, and sleep BP but not for the surge between the sleep and awake time at the 24-month time point.

CONCLUSIONS

These data demonstrate for the first time the importance of 24-hour systolic BP in the progression of brain white matter hyperintensity volume burden associated with impairment of cognitive function in older people. The 24-hour systolic BP may be a potential target for intervention in the elderly to reduce vascular disease of the brain and impairment of function.

Obstructive sleep apnoea syndrome promotes reversal albuminuria during sleep

INTRODUCTION

Sleep apnoea syndrome (OSAS) may induce albuminuria during sleep which could reflect one of the possible pathogenetic mechanisms regarding cardiovascular risk.

MATERIALS AND METHODS

We studied 224 patients with newly diagnosed OSAS, free of any chronic disease, and any regular drug therapy. The levels of urine albumin/creatinine ratio (ACR) before (ACR-bsleep) and immediately after (ACR-asleep) a sleep study were determined. The same procedure was repeated during the first night on CPAP treatment (n = 121) and in 46 reevaluated patients, after 3 months, on CPAP therapy. Ambulatory blood pressure was monitored in 133 of the patients.

RESULTS

ACR-asleep was significantly higher in patients (17.82 ± 31.10 mg/g) compared with controls (6.54 ± 6.53 mg/g, p < 0.001). The mean percent change in ACR levels between after and before sleep (%dACR) was increased by 8.82% ± 61.06 in OSAS patients and reduced by 26.87% ± 18.95 in controls (p < 0.001). During the first sleep study on CPAP, the %dACR was reduced by 21.40% ± 24.59, in contrast to the increase observed during the initial study (10.73% ± 69.93, p < 0.001). This beneficial effect of CPAP treatment was preserved in the reevaluated patients. The %dACR was +29.33% ± 57.67 in nondippers (44% of the patients) and -5.57% ± 40.81 in dippers (p < 0.001). It was negatively correlated to the percent change of systolic (rho = -0.284, p = 0.003) and diastolic (rho = -0.341, p < 0.001) blood pressure between wakefulness and sleep. Contrary to normal people, ACR is increased in OSAS patients during sleep, at least partially, related to the nondipping phenomenon observed in these patients. Following CPAP treatment, urinary albumin excretion is reduced.

[Impact of components and methods of measurement of blood pressure on damage of target organs and cardiovascular complications in arterial hypertension]

BACKGROUND

The goal of this study was to evaluate the relative association of several components of blood pressure (BP), as measured in the office and by ambulatory monitoring (ABPM), with clinically useful indicators of target organ damage and cardiovascular events (CE) in essential hypertensive patients.

PATIENTS AND METHOD

We retrospectively included 390 hypertensives (55% men; mean age: 56 years) between 1989 and 1998. All them had a baseline office BP measurement and a valid 24-hour ABPM record, both performed while the patient was free of antihypertensive therapy. Estimates of target organ damage included electrocardiographic indexes of left ventricular hypertrophy (Cornell and Sokolow-Lyon), serum creatinine, 24-hour urine protein excretion and creatinine clearance. Multiple linear regression and logistic regression analyses were used to evaluate the relationship between BP and target organ damage or CE.

RESULTS

Forty-nine patients had CE (26 stroke, 18 myocardial infarction and 5 both). The BP parameter correlating better with cardiovascular events was office pulse pressure (multivariate odds ratio: 1.03; CI 95%: 1.00-1.05; p = 0.0095). Nevertheless, cardiac growth indexes correlated better with ABPM measurements. In fact, Cornell index correlated with night-time systolic BP (standardized regression coefficient beta: 0.260; p < 0.001) and Sokolow-Lyon index correlated with day-time systolic BP ( beta: 0.257; p < 0.001). Creatinine clearance inversely correlated with night-time pulse pressure ( beta: 0.122; p = 0.017) while proteinuria correlated better with 24-hour systolic BP ( beta: 0.390; p < 0.001).

CONCLUSIONS

Whereas office BP (especially pulse pressure) is associated with the development of CE, ABPM estimates show a better association with target organ damage, especially systolic and pulse pressures.

Microalbuminuria is associated with unfavourable cardiac geometric adaptations in essential hypertensive subjects

We sought in this study to examine the relationship between microalbuminuria and cardiac geometry since a slight increased urinary albumin excretion (UAE) and increased left ventricular (LV) mass have both been identified as predictors of cardiovascular events in hypertensive subjects. For this purpose, microalbuminuria was determined in three non-consecutive 24-h urine samples as UAE of 20-200 mg/24 h in a group of 249 untreated hypertensive subjects. Echocardiographic classification of patients into LV geometric patterns was based on relative wall thickness values and on gender-specific values for LV mass index (LVMI). The group of patients with microalbuminuria (n = 119) was matched for age, sex, body mass index, smoking status and plasma cholesterol level with the group of patients without microalbuminuria (n = 130). Subjects with microalbuminuria had significantly increased LVMI (111 vs 90 g/m(2), P < 0.0001), relative wall thickness (0.46 vs 0.41, P < 0.001) and office systolic and diastolic blood pressure (161 vs 148 and 101 vs 97 mmHg, respectively, P < 0.005). For the pooled population, UAE was positively correlated to LVMI (r = 0.46, P < 0.001) and relative wall thickness (r = 0.47, P < 0.001). In the entire population, normal LV geometry, concentric LV remodelling, eccentric and concentric LV hypertrophy was found in 34%, 33%, 12% and 21%, respectively. The prevalence of normal LV geometry was significantly higher in normoalbuminuric compared with microalbumnuric subjects (55 vs 14%, P < 0.001) while the prevalence of concentric LV hypertrophy was significantly higher in microalbuminuric compared with normoalbuminuric subjects (32 vs 5%, P < 0.0001). Multiple regression analysis revealed that concentric LV hypertrophy was significantly associated with increased values of UAE and mean arterial pressure. In conclusion, the higher prevalence of unfavourable LV geometric patterns in hypertensive subjects with microalbuminuria compared with those without microalbuminura, may account for the worse cardiovascular outcomes associated with the presence of an increased UAE in hypertensive subjects.

Microalbuminuria, an integrated marker of cardiovascular risk in essential hypertension

This paper reviews the existing epidemiological and clinical evidence about the relationships of non-diabetic microalbuminuria with cardiovascular risk factors such as elevated blood pressure (BP), systolic particularly, cardiac hypertrophy, adverse metabolic status, smoking habits, elevated angiotensin II levels, endothelial dysfunction, acute and perhaps subclinical inflammation. Because of that unique property of reflecting the influence of so many clinically relevant parameters, microalbuminuria may legitimately be defined as an integrated marker of cardiovascular risk, an unique profile among the several prognostic predictors available to stratify risk in hypertensive patients. Recent cohort studies also showed associations with cardiovascular morbidity and mortality independently from conventional atherogenic factors. This behaviour, whose understanding still needs further elucidation, suggests to measure albuminuria and to screen patients at a higher absolute risk in whom preventive treatment is expected to be more beneficial than in those with a lower absolute risk.

Microalbuminuria is associated with abnormal thoracic aortic mechanics in essential hypertension

In a population of 162 patients with currently untreated essential hypertension, those with microalbuminuria (n = 75) had significantly impaired elastic properties of the proximal ascending thoracic aorta compared with their normoalbuminuric counterparts (n = 87), whereas urinary albumin excretion was a significant predictor of aortic mechanics in the entire population. Impaired aortic mechanics in microalbuminuric hypertensives were not fully accounted for by clustering of classic risk factors for atherosclerosis, and constitute a finding that may entail additional long-term cardiovascular risk in this subgroup of patients.

Microalbuminuria in essential hypertension

Urinary excretion of albumin exceeds normal values in 10 to 25% of patients with essential hypertension. The level of albuminuria is highly correlated with arterial pressure, and more closely with ambulatory arterial pressure. The interaction between albuminuria and arterial pressure is enhanced by overweight, smoking, protein intake, insulin resistance, lipid abnormalities, and possibly genotypes of the components of the renin-angiotensin system. The renal mechanisms of microalbuminuria are not well elucidated. Notably, an increase in filtration fraction suggestive of intraglomerular hypertension was observed in patients with hyperfiltration. Microalbuminuria may be a marker of diffuse vascular abnormalities predisposing to cardiovascular disease and/or hypertensive renal disease heralding future renal failure, but its predictive value needs to be tested in more long-term follow-up studies. Antihypertensive treatment has a varied influence on albuminuria; angiotensin-converting enzyme inhibitors may correct this abnormality (at least partially) better than other agents.