Maura Ravera

Prevalence and Clinical Correlates of Microalbuminuria in Essential Hypertension: The MAGIC Study

Abstract The prevalence of microalbuminuria and its relationship with several cardiovascular risk factors and target organ damage were evaluated in a cohort of 787 untreated patients with essential hypertension. Albuminuria was measured as the albumin-to-creatinine ratio in three nonconsecutive, first morning urine samples. The prevalence of microalbuminuria was 6.7%. Albuminuric patients were more likely to be men and to be characterized by higher blood pressure, body mass index, and uric acid levels and lower HDL cholesterol and HDL cholesterol−to−LDL cholesterol ratio. Piecewise linear regression analysis demonstrated that uric acid and diastolic blood pressure significantly influence albuminuria and together account for a large part of its variations. K-means cluster analysis performed on the entire cohort of patients confirmed that microalbuminuria is associated with a worse cardiovascular risk profile. Furthermore, microalbuminuria was associated with the presence of target organ damage (eg, electrocardiographic [ECG] abnormalities and retinal vascular changes). Age and the presence of microalbuminuria act as independent risk factors for the development of ECG abnormalities and retinal vascular changes. Cluster analysis allowed us to identify three subgroups of patients who differed in the presence or absence of microalbuminuria, retinopathy, and ECG abnormalities. We conclude that the prevalence of microalbuminuria in essential hypertension is lower than previously reported. Increased urinary albumin excretion is associated with a worse cardiovascular risk profile and is a concomitant indicator of early target organ damage.

Microalbuminuria, Cardiovascular, and Renal Risk in Primary Hypertension

Microalbuminuria is defined as abnormal urinary excretion of albumin between 30 and 300 mg/d. It can be measured accurately by several widely available and sensitive methods. This abnormality can be found in 8 to 15% of nondiabetic patients with primary hypertension, although its prevalence varies greatly in the literature, likely due to differences in the methods used to detect it and to the criteria applied in the selection of patients. The pathogenetic mechanisms leading to the development of microalbuminuria are still not completely known. BP load and increased systemic vascular permeability, possibly due to early endothelial damage, seem to play a major role. Increased urinary albumin excretion has been associated with several unfavorable metabolic and nonmetabolic risk factors and subclinical hypertensive organ damage. In fact, a higher prevalence of concentric left ventricular hypertrophy and subclinical impairment of left ventricular performance, as well as the presence of carotid atherosclerosis, have been reported in patients with microalbuminuria. These associations might per se justify a greater incidence of cardiovascular events. Long-term longitudinal studies have recently confirmed the unfavorable prognostic significance of microalbuminuria in hypertensive patients. It has also been hypothesized that microalbuminuria might be a forerunner of overt renal damage in primary hypertension. Clinical studies, however, have shown conflicting results, and this hypothesis has to be considered tempting but speculative at present. In conclusion, microalbuminuria is a specific, integrated marker of cardiovascular risk and target organ damage in primary hypertension and one that is suitable for identifying patients at higher global risk. A wider use of this test in the diagnostic work-up of hypertensive patients is recommended.

Microalbuminuria Is an Early Marker of Target Organ Damage in Essential Hypertension

Microalbuminuria has been associated with a cluster of metabolic and nonmetabolic risk factors, suggesting that it might indicate the presence of generalized microvascular damage in patients with essential hypertension. To explore whether microalbuminuria is associated with early target organ damage, two groups of essential hypertensive patients, with (n = 17) (HtAlb+) and without (n = 16) (HtAlb-) microalbuminuria, and a control group (C) of healthy normotensive subjects (n = 20) were studied. The study groups, selected among participants of a large epidemiologic trial, were carefully matched for several potentially confounding variables such as gender, age, duration of hypertension, and body mass index. Albumin excretion rate was evaluated by radioimmunoassay in three nonconsecutive timed overnight collections after 3 weeks of pharmacologic wash-out. Left ventricular mass was assessed by M-B-mode echocardiography, carotid wall thickness by a high resolution ultrasound scan, and renal vascular impedance by Doppler scan. Office as well as 24-h ambulatory pressure monitoring (Takeda TM-2420) were also evaluated. There was no difference between the two hypertensive groups for office and 24-h blood pressure levels except for a lower daytime/nighttime systolic blood pressure ratio in the group with microalbuminuria. Microalbuminuric patients showed signs of early organ damage as compared to normoalbuminuric patients and normal subjects, namely greater left ventricular mass indices (LVMI 167+/-7 g/m2 in HtAlb+; 139+/-9 g/m2 in HtAlb-; 118+/-5 g/m2 in C, P < .001) and increased wall thickness of common carotid arteries (intima plus media thickness 12.5+/-0.2 mm in HtAlb+; 11.7+/-0.3 mm in HtAlb-; 11.2+/-0.2 mm in C, P < .001) as well as higher intrarenal vascular resistance (mean resistive index 0.62+/-0.01 in HtAlb+; 0.59+/-0.01 in HtAlb-; 0.59+/-0.01 in C, P < .05). In conclusion, microalbuminuria is an early marker of diffuse target organ damage in essential hypertension and therefore can be useful to identify patients for whom more aggressive preventive strategies or additional treatment measures are advisable.

Importance of Blood Pressure Control in Chronic Kidney Disease

Arterial hypertension together with proteinuria is one of the most important factors associated with the progression of both diabetic and nondiabetic chronic kidney disease. In this review, the role of hypertension and proteinuria in renal disease progression, the BP target that should be achieved to slow the progression of renal damage, and the influence of baseline and current proteinuria on the renoprotective effects of antihypertensive therapy are discussed thoroughly. The interaction between the renoprotective effects of specific antihypertensive agents--mostly angiotensin-converting enzyme inhibitors and angiotensin receptor blockers--and the level of achieved BP also are evaluated. The body of evidence provided by several studies emphasizes the importance of both lowering BP and inhibiting the renin-angiotensin system as specific goals for renal and cardiovascular protection in chronic kidney disease.

Mild Renal Dysfunction and Subclinical Cardiovascular Damage in Primary Hypertension

Abstract—The presence of mild renal dysfunction is associated with high cardiovascular morbidity and mortality rates in patients with primary hypertension. The pathophysiological mechanisms underlying this association are currently unknown. We investigated the relation between mild renal dysfunction and subclinical cardiovascular organ damage in 358 never previously treated patients with primary hypertension. Mild renal dysfunction was defined as a creatinine clearance <60 mL/min and/or the presence of microalbuminuria. Left ventricular mass index and carotid intima-media thickness were assessed by ultrasound scan. The prevalence of mild renal dysfunction, left ventricular hypertrophy, and carotid plaque was 18%, 48%, and 28%, respectively. Mild renal dysfunction was related to the presence of several risk factors, such as older age, higher blood pressure levels and lipid status, and smoking habits. Patients with the highest left ventricular mass and carotid intima-media thickness (upper quartiles) showed a higher prevalence of mild renal dysfunction (P <0.0001). After adjusting for duration of hypertension, mean blood pressure, smoking habits, and age, we found that the risk of left ventricular hypertrophy and/or carotid atherosclerosis increased by 43% with each SD reduction in creatinine clearance, and by 89% with each SD increase in albuminuria. Mild renal dysfunction is associated with preclinical end-organ damage in patients with primary hypertension. These data may help explain the high cardiovascular mortality rates reported in patients with low glomerular filtration rate or with increased albuminuria. The evaluation of creatinine clearance and urinary albumin excretion could be useful for identifying subjects at higher cardiovascular risk.

Microalbuminuria identifies overall cardiovascular risk in essential hypertension: an artificial neural network-based approach.

Background Ultrasound (US) examination of heart and carotid arteries provides an accurate assessment of target organ damage (TOD) and may influence the stratification of the absolute cardiovascular risk profile. Microalbuminuria has recently proved to be a useful cost-effective marker of increased cardiovascular risk but is still too often neglected in clinical practice. Objective To evaluate how well artificial neural networks (ANNs) predict cardiovascular risk stratification by means of routine data and urinary albumin excretion, as compared to prediction by the clinical work-up suggested by the International Society of Hypertension (ISH), with and without ultrasound-determined TOD. Methods A group of 346 never previously treated essential hypertensives (212 men, 134 women, mean age 47 ± 9 years) was studied. Risk was stratified according to the criteria suggested by the 1999 WHO/ISH guidelines; first, by routine procedures alone, and subsequently by reassessment, using data on cardiac and vascular structures obtained by US evaluation. The ANN was trained and tested to predict the overall cardiovascular risk on the basis of routine clinical data and urinary albumin excretion (UAE). The impact of these three approaches on the determination of cardiovascular risk profile was evaluated. Results According to the first classification, 5.5% (n = 19) of patients were considered at low risk, 47.3% (n = 164) at medium, 26.7% (n = 92) at high and 20.6% (n = 71) at very high risk. A marked change in risk stratification, namely an increase in the prevalence of high- and very-high-risk patients (2.3% low, 29.8% medium, 42.8% high and 25.2% very high risk; χ2 15.201, P < 0.0001), was obtained when US examination of TOD was taken into consideration. On the basis of routine clinical data and UAE, the artificial neural network successfully predicted overall cardiovascular risk and allocated patients in different classes as accurately as the US-based evaluation. Conclusions The use of US techniques allows a more precise stratification of absolute cardiovascular risk in hypertensive patients as compared to routine clinical data. An ANN can accurately identify the patients’ risk status by using low-cost routine data and UAE. These results further emphasize the value of UAE in the stratification of cardiovascular risk.

Microalbuminuria is an integrated marker of subclinical organ damage in primary hypertension

Increased urine albumin excretion is associated with an unfavourable cardiovascular risk profile and prognosis in primary hypertension, even though its pathogenesis is currently unknown. Microalbuminuria (Mi) has been proposed as an integrated marker to identify patients with subclinical organ damage, but its routine use is still too often neglected in clinical practice. The aim of our study was to evaluate the relationship between urinary albumin excretion and early signs of subclinical target organ damage (TOD), namely left ventricular hypertrophy and carotid atherosclerosis in a large group of non diabetic hypertensive patients. A group of 346 never treated patients with primary hypertension (212 men, 134 women, mean age 47 ± 9 years) referred to our clinic were included in the study. They underwent the following procedures: (1) family and personal medical history and physical examination; (2) clinical blood pressure measurement; (3) routine blood chemistry and urine analysis including determination of urinary albumin excretion (ACR); (4) electrocardiogram; (5) ultrasound evaluation of left ventricular mass (LVMI) and carotid artery thickness (IMT). The overall prevalence of Mi, left ventricular hypertrophy, and carotid plaque was 13, 51, and 24% respectively. Mi was significantly correlated with LVMI (P < 0.0001), IMT (P < 0.0001) and several metabolic and non-metabolic risk factors (blood pressure, body mass index, serum lipids). Cluster analysis identified three subgroups of patients who differ significantly with regards to TOD and albuminuria (P ⩽ 0.001 for each of the examined variables). Patients with higher IMT and LVMI values also showed increased ACR levels. Furthermore, patients with microalbuminuria were more likely to have both LVH and IMT values above the median for the study population (OR 21, C.I. 4.6–99.97, P < 0.0001). Mi is an integrated marker of subclinical organ damage in patients with primary hypertension. Evaluation of urinary albumin excretion is a specific, cost-effective way to identify patients at higher risk for whom additional preventive and therapeutic measures are advisable.

Changes in Renal Resistive Index and Urinary Albumin Excretion in Hypertensive Patients under Long-Term Treatment with Lisinopril or Nifedipine GITS

Introduction: Increased renal vascular resistance and microalbuminuria are associated with hypertensive target organ damage and may be predictors of hypertensive nephrosclerosis. Aim: We investigated changes in renal resistive index (RI) and urinary albumin excretion (UAE) in a group of patients with primary hypertension before and during long-term antihypertensive treatment. Methods: Thirty-two patients were randomized to receive antihypertensive treatment with either a calcium channel blocker (nifedipine GITS, up to 90 mg/day, n = 16) or an ACE inhibitor (lisinopril, up to 20 mg/day, n = 16), alone or in association with a diuretic (chlortalidone, 25 mg/day). Blood pressure, renal resistive index (by US Doppler) and UAE (mean of three nonconsecutive timed urinary collections, µg/min) were evaluated at baseline and over the course of 24 months of treatment. Results: Both regimens effectively lowered blood pressure (mean blood pressure from 123 ± 1.8 at baseline to 103 ± 1.5 mm Hg at 24 months in the lisinopril group and from 122 ± 1.9 at baseline to 104 ± 0.8 at 24 months in the nifedipine group, p < 0.001 for both groups). Overall, blood pressure decrease was associated with a reduction in UAE and no change in RI throughout the study. However, despite similar blood pressure reduction, the two regimens showed different specific effects. Lisinopril was associated with a significant decrease in both UAE (33.8 ± 16.2 at baseline and 9.1 ± 2.1 at 24 months, p < 0.01) and renal RI (0.61 ± 0.02 at baseline and 0.56 ± 0.04 at 24 months, p < 0.05) while nifedipine GITS did not significantly influence UAE (35.7 ± 12.2 at baseline and 31.2 ± 12.1 at 24 months, n.s.) or RI (0.61 ± 0.01 at baseline and 0.59 ± 0.02 at 24 months, n.s.). Conclusion: Effective blood pressure control over a long period of time reduces the severity of organ damage, namely UAE while maintaining renovascular resistance in patients with essential hypertension. Different classes of antihypertensive agents might convey additional specific renal protection beyond blood pressure control. These data could be useful in devising individualized therapeutic strategies in hypertensive patients at increased renal risk.

Renal and Cardiovascular Protection in Type 2 Diabetes Mellitus: Angiotensin II Receptor Blockers

Aggressive treatment of hypertension is effective in reducing both microvascular and macrovascular complications in type 2 diabetes, and target BP less than 130/85 or 130/80 mmHg are now recommended. Inhibition of renin angiotensin aldosterone system (RAAS) plays an essential role in the treatment of hypertension and diabetes-related complications. Studies focusing on renal end-points suggest that angiotensin-converting enzyme inhibitors (ACE-I) are more effective than other traditional agents in reducing the onset of clinical proteinuria in both type 1 and type 2 diabetic patients with incipient nephropathy, mainly in normotensive ones (secondary prevention). However, several small trials in type 2 diabetic patients with overt nephropathy (tertiary prevention) failed to demonstrate a specific renoprotective role for ACE-I, at variance with type 1 diabetes. Three recent large trials address the question of whether angiotensin II receptor blockers (ARB) prevent the development of clinical proteinuria or delay the progression of nephropathy in type 2 diabetes. The IRMA study showed that irbesartan is more effective than conventional therapy in preventing the development of clinical proteinuria and in favoring the regression to normoalbuminuria for comparable BP control in patients with incipient nephropathy. The IDNT and RENAAL trials showed that ARB are more effective than traditional antihypertensive therapies in reducing progression toward end-stage renal failure (ESRF) in type 2 diabetic patients with overt nephropathy independently of changes in BP. Moreover, a reduction in hospitalizations for heart failure was demonstrated for ARB-treated patients compared with placebo. Furthermore, the LIFE study showed that losartan is more effective than conventional therapy in reducing cardiovascular morbidity and mortality in a cohort of diabetic patients with hypertension and left ventricular hypertrophy. In conclusion, ARB seem to be effective in both preventing renal damage and reducing progression toward ESRF in type 2 diabetic patients. Thus, the guidelines for the prevention and treatment of diabetic nephropathy are now changed. In type 1 diabetes ACE-I are the first-choice drug; in type 2 diabetes, ARB are considered first-choice drugs in secondary prevention as well as ACE-I and have been now elected the unique first-choice drug in tertiary prevention of ESRF. Finally, ARB should be considered as the first-choice drug in cardiovascular prevention too, as well as ACE-I.

Mild Renal Dysfunction and Cardiovascular Risk in Hypertensive Patients

Mild renal dysfunction, defined as GFR <60 to 70 ml/min and/or the presence of increased urinary albumin excretion, is associated with higher cardiovascular morbidity and mortality in primary hypertension. The aim of the present study was to investigate the relationship between renal dysfunction and target organ damage (TOD), namely left ventricular hypertrophy (LVH), retinal vascular changes, and carotid atherosclerosis, in a large cohort of unselected middle-aged hypertensive patients with normal serum creatinine. A group of 934 untreated patients with primary hypertension (543 men, 391 women; mean age 50 +/- 11 yr) was studied. Renal function was estimated by the creatinine clearance using the Cockcroft-Gault formula and by the presence of albuminuria, measured as the albumin to creatinine ratio (A/C) in first morning urine samples. LVH was determined according to electrocardiographic criteria, and retinal vascular changes were evaluated by direct ophthalmoscopy in all patients. In a subgroup of patients (n = 340; 208 men, 132 women; mean age 47 +/- 9), the presence and extent of cardiac and vascular organ damage was also assessed by ultrasound techniques. Creatinine clearance was on the average 82 +/- 20 ml/min. The overall prevalence of ECG-detected LVH and retinopathy was 12 and 49%, respectively. Creatinine clearance was inversely related to duration of disease, systolic BP, serum glucose, total cholesterol, LDL cholesterol, and early signs of TOD, namely retinal vascular changes and LVH. Patients in the bottom quintile of creatinine clearance showed higher prevalence of both ECG-determined LVH (P = 0.04) and retinal vascular changes (P = 0.02). In the subgroup of patients who underwent ultrasound evaluation of cardiovascular structures, the prevalence of mild renal dysfunction was 18%, whereas the prevalence of LVH and carotid plaque was 49 and 26%, respectively. Patients with mild renal dysfunction showed higher left ventricular mass and increased intima-media thickness (P < 0.0001), as well as higher prevalence of LVH and carotid plaque as compared with those with normal renal function. Controlling for duration of hypertension and mean BP, the risk of TOD in our cohort increased by 20% for each 10 ml/min decrease in creatinine clearance and by 30% for each 0.2 mg/mmol increase in Log A/C. In conclusion, mild renal dysfunction is associated with preclinical end-organ damage in patients with primary hypertension. These data may help to explain the observed increase in cardiovascular mortality reported in these patients. The evaluation of creatinine clearance and urinary albumin excretion could be useful for identifying patients who are at higher cardiovascular risk.