The kidney as a sensor of cardiovascular risk in essential hypertension

Utility of urinary albumin excretion as an index for stratifying the residual cardiovascular risk in patients undergoing antihypertensive agents treatment

BACKGROUND

Patients treated with antihypertensive medication, even those with well controlled blood pressure (BP), are at higher risk for the development of atherosclerotic cardiovascular disease (ASCVD) in comparison to nonhypertensive individuals with optimal risk levels. We hypothesized that this residual risk could be stratified based on urinary albumin excretion (UAE).

METHODS

A total of 13 082 middle-aged and older individuals with SBP/DBP of less than 160/100 mmHg and urinary albumin-to-creatinine ratios (UACRs) of less than 300 mg/g, and who were free from ASCVD events, were followed to investigate the incidence of ASCVD. The baseline BP was classified into four categories: normal BP (BP1), high normal BP (BP2), elevated BP (BP3), and grade 1 hypertension (BP4) based on the 2019 Japanese Society of Hypertension guidelines.

RESULTS

After an average 10.6 ± 2.6 years of follow-up, the multivariable hazard ratio for the development of ASCVD (n = 994) was already increased in medicated hypertensive patients with BP1 in comparison with untreated individuals with BP1; however, among medicated hypertensive patients, this risk was separated between the UAE groups, which were classified according to the median UACR (male, 15.4 mg/g; female, 19.0 mg/g). In medicated hypertensive patients with any category of BP1-BP3, the adjusted risk of the development of ASCVD in those with lower and higher UACRs was comparable to that observed in untreated individuals in the BP1 and BP4 categories, respectively.

CONCLUSION

In medicated patients with well controlled hypertension, UAE is useful for stratifying the residual risk of developing ASCVD in comparison to nonhypertensive individuals with optimal risk levels.

Microalbuminuria and cardiorenal risk: old and new evidence in different populations

Since the association of microalbuminuria (MAU) with cardiovascular (CV) risk was described, a huge number of reports have emerged. MAU is a specific integrated marker of CV risk and targets organ damage in patients with hypertension, chronic kidney disease (CKD), and diabetes and its recognition is important for identifying patients at a high or very high global CV risk. The gold standard for diagnosis is albumin measured in 24-hour urine collection (normal values of less than 30 mg/day, MAU of 30 to 300 mg/day, macroalbuminuria of more than 300 mg/day) or, more practically, the determination of urinary albumin-to-creatinine ratio in a urine morning sample (30 to 300 mg/g). MAU screening is mandatory in individuals at risk of developing or presenting elevated global CV risk. Evidence has shown that intensive treatment could turn MAU into normoalbuminuria. Intensive treatment with the administration of an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker, in combination with other anti-hypertensive drugs and drugs covering other aspects of CV risk, such as mineralocorticoid receptor antagonists, new anti-diabetic drugs, and statins, can diminish the risk accompanying albuminuria in hypertensive patients with or without CKD and diabetes.

Intravital imaging of the kidney in a rat model of salt-sensitive hypertension

Hypertension is one of the most prevalent diseases worldwide and a major risk factor for renal failure and cardiovascular disease. The role of albuminuria, a common feature of hypertension and robust predictor of cardiorenal disorders, remains incompletely understood. The goal of this study was to investigate the mechanisms leading to albuminuria in the kidney of a rat model of hypertension, the Dahl salt-sensitive (SS) rat. To determine the relative contributions of the glomerulus and proximal tubule (PT) to albuminuria, we applied intravital two-photon-based imaging to investigate the complex renal physiological changes that occur during salt-induced hypertension. Following a high-salt diet, SS rats exhibited elevated blood pressure, increased glomerular sieving of albumin (GSC_alb = 0.0686), relative permeability to albumin (+Δ16%), and impaired volume hemodynamics (-Δ14%). Serum albumin but not serum globulins or creatinine concentration was decreased (-0.54 g/dl), which was concomitant with increased filtration of albumin (3.7 vs. 0.8 g/day normal diet). Pathologically, hypertensive animals had significant tubular damage, as indicated by increased prevalence of granular casts, expansion and necrosis of PT epithelial cells (+Δ2.20 score/image), progressive augmentation of red blood cell velocity (+Δ269 µm/s) and micro vessel diameter (+Δ4.3 µm), and increased vascular injury (+Δ0.61 leakage/image). Therefore, development of salt-induced hypertension can be triggered by fast and progressive pathogenic remodeling of PT epithelia, which can be associated with changes in albumin handling. Collectively, these results indicate that both the glomerulus and the PT contribute to albuminuria, and dual treatment of glomerular filtration and albumin reabsorption may represent an effective treatment of salt-sensitive hypertension.

Left ventricular dilatation and subclinical renal damage in primary hypertension

OBJECTIVE

A new classification of left ventricular geometry based on left ventricular dilatation and concentricity has recently been developed. This classification identifies subgroups differing with regard to systemic haemodynamics, left ventricular function and cardiovascular prognosis. We investigated the relationship between the new classification of left ventricular geometry and subclinical renal damage, namely urine albumin excretion and early intrarenal vascular changes in primary hypertensive patients.

METHODS

A total of 449 untreated hypertensive patients were studied. Four different patterns of left ventricular hypertrophy (eccentric nondilated, eccentric dilated, concentric nondilated and concentric dilated hypertrophy) were identified by echocardiography. Albuminuria was measured as the albumin-to-creatinine ratio. Early intrarenal vascular changes, expressed as the renal volume to resistive index ratio, were evaluated by ultrasound and Doppler scan.

RESULTS

Patients with concentric dilated left ventricular hypertrophy had higher albumin excretion rates (P = 0.0258) and prevalence of microalbuminuria (P < 0.0001) and lower renal volume to resistive index ratio than patients with concentric nondilated hypertrophy (P = 0.0093). Patients with eccentric dilated hypertrophy showed a higher prevalence of microalbuminuria than patients with eccentric nondilated hypertrophy (P < 0.0001). Moreover, patients with chamber dilatation showed a higher prevalence of microalbuminuria (P = 0.0002) and lower renal volume to resistive index ratio (P = 0.0107) than patients without chamber dilatation. After adjusting for potentially confounding variables, left ventricular chamber dilatation was an independent predictor of subclinical renal damage.

CONCLUSION

Left ventricular dilatation is associated with subclinical renal damage in hypertension. These findings extend previous reports and provide a pathophysiological rationale for the observed unfavourable prognosis in patients with left ventricular dilatation.

Subclinical Kidney Damage in Hypertensive Patients: A Renal Window Opened on the Cardiovascular System. Focus on Microalbuminuria

The kidney is one of the major target organs of hypertension.Kidney damage represents a frequent event in the course of hypertension and arterial hypertension is one of the leading causes of end-stage renal disease (ESRD).ESRD has long been recognized as a strong predictor of cardiovascular (CV) morbidity and mortality. However, over the past 20 years a large and consistent body of evidence has been produced suggesting that CV risk progressively increases as the estimated glomerular filtration rate (eGFR) declines and is already significantly elevated even in the earliest stages of renal damage. Data was supported by the very large collaborative meta-analysis of the Chronic Kidney Disease Prognosis Consortium, which provided undisputable evidence that there is an inverse association between eGFR and CV risk. It is important to remember that in evaluating CV disease using renal parameters, GFR should be assessed simultaneously with albuminuria.Indeed, data from the same meta-analysis indicate that also increased urinary albumin levels or proteinuria carry an increased risk of all-cause and CV mortality. Thus, lower eGFR and higher urinary albumin values are not only predictors of progressive kidney failure, but also of all-cause and CV mortality, independent of each other and of traditional CV risk factors.Although subjects with ESRD are at the highest risk of CV diseases, there will likely be more events in subjects with mil-to-moderate renal dysfunction, because of its much higher prevalence.These findings are even more noteworthy when one considers that a mild reduction in renal function is very common in hypertensive patients.The current European Society of Hypertension (ESH)/European Society of Cardiology (ESC) guidelines for the management of arterial hypertension recommend to sought in every patient signs of subclinical (or asymptomatic) renal damage. This was defined by the detection of eGFR between 30 mL/min/1.73 m² and 60 mL/min/1.73 m² or the presence of microalbuminuria (MAU), that is an amount of albumin in the urine of 30-300 mg/day or an albumin/creatinine ratio, preferentially on morning spot urine, of 30-300 mg/g.There is clear evidence that urinary albumin excretion levels, even below the cut-off values used to define MAU, are associated with an increased risk of CV events. The relationships of MAU with a variety of risk factors, such as blood pressure, diabetes and metabolic syndrome and with several indices of subclinical organ damage, may contribute, at least in part, to explain the enhanced CV risk conferred by MAU. Nonetheless, several studies showed that the association between MAU and CV disease remains when all these risk factors are taken into account in multivariate analyses. Therefore, the exact pathophysiological mechanisms explaining the association between MAU and CV risk remain to be elucidated. The simple search for MAU and in general of subclinical renal involvement in hypertensive patients may enable the clinician to better assess absolute CV risk, and its identification may induce physicians to encourage patients to make healthy lifestyle changes and perhaps would prompt to more aggressive modification of standard CV risk factors.

Predictive role of renal resistive index for clinical outcome after revascularization in hypertensive patients with atherosclerotic renal artery stenosis: a monocentric observational study

Background

The present study evaluated the predictive value of renal resistive index (RI) for renal function and blood pressure (BP) outcome in hypertensive patients with unilateral atherosclerotic renal artery stenosis submitted to successful revascularization.

Methods

In 158 hypertensive patients with atherosclerotic renal artery stenosis RI was acquired. Twelve months after revascularization, they were classified on the basis of renal function and BP outcome as benefit (BP < 140/90 mmHg or diastolic BP reduction > 15 mmHg with the same of reduced drugs; decrease in glomerular filtration rate > 20%), or failure.

Results

Regarding renal function outcome, RI in the stenotic and in the contralateral kidney were significantly higher in patients with failure (n = 20) than in those with benefit (0.72 ± 0.11 vs 0.61 ± 0.11 and 0.76 ± 0.08 vs 0.66 ± 0.09, p < 0.05). Among different cutpoints generated, RI in the contralateral kidney >0.73 provided the largest area under the curve (0.77), and the highest sensitivity (80%) and specificity (72%). In the multivariate logistic regression analysis, RI in the contralateral kidney >0.73 was an independent predictor of a failure in renal function outcome.

Regarding BP outcome, patients with no benefit from revascularization (n = 60) had similar RI in the stenotic and contralateral kidney (p = ns), but presented higher pulse pressure, albuminuria and hypertension duration in comparison to patients with improved BP control.

Conclusions

RI in the contralateral kidney is an independent predictor of renal function outcome after successful revascularization in hypertensive patients with unilateral atherosclerotic renal artery stenosis, whereas it is not able to predict blood pressure outcome.

Estimated glomerular filtration rate is associated with both arterial stiffness and N-terminal pro-brain natriuretic peptide in newly diagnosed hypertensive patients

Even a slight decrease in the glomerular filtration rate (GFR) is an independent risk factor for cardiovascular disease. Arterial stiffness, left ventricular hypertrophy and N-terminal pro-brain natriuretic peptide (NT-proBNP) are independent risk factors for cardiovascular disease, which are particularly common in end-stage renal disease. We aimed to evaluate the association between GFR with arterial stiffness, left ventricle mass (LVM) and NT-proBNP in hypertensive subjects with normal to mildly impaired renal function. The study population consisted of 285 newly diagnosed hypertensive patients (mean age; 49.9 ± 11.8 years). GFR was estimated (eGFR) by the Modification of Diet in Renal Disease formula. Pulse wave velocity (PWV) and augmentation index (AIx), which reflects arterial stiffness, were calculated using the single-point method via the Mobil-O-Graph® ARCsolver algorithm. LVM was obtained by echocardiography. Plasma NT-proBNP was measured by electrochemiluminescence. The patients were divided into two groups according to the median eGFR value (eGFRlow group <101 ml/min/1.73 m(2) and eGFRhigh group ≥ 101 ml/min/1.73 m(2)). LVM and NT-proBNP values were higher in eGFRlow group compared with eGFRhigh group (p<0.05). Pulse wave velocity and augmentation index values were higher in eGFRlow group compared with eGFRhigh group (p<0.05, for all). Multiple linear regression analysis showed that eGFR was independently associated with PWV (β=-0.422, p<0.001) and NT-proBNP (β=-0.404, p<0.001). Present study showed that eGFR was independently associated with PWV and NT-proBNP values. Importantly, these findings may explain, in part, the increase in cardiovascular risk in with slightly impaired renal function.

Astragalus injection for hypertensive renal damage: a systematic review

Objective. To evaluate the effectiveness of astragalus injection (a traditional Chinese patent medicine) for patients with renal damage induced by hypertension according to the available evidence. Methods. We searched MEDLINE, China National Knowledge Infrastructure (CNKI), Chinese VIP Information, China Biology Medicine (CBM), and Chinese Medical Citation Index (CMCI), and the date of search starts from the first of database to August 2011. No language restriction was applied. We included randomized controlled trials testing astragalus injection against placebo or astragalus injection plus antihypertensive drugs against antihypertensive drugs. Study selection, data extraction, quality assessment, and data analyses were conducted according to the Cochrane review standards. Results. 5 randomized trials (involving 429 patients) were included and the methodological quality was evaluated as generally low. The pooled results showed that astragalus injection was more effective in lowering β₂-microglobulin (β₂-MG), microalbuminuria (mAlb) compared with placebo, and it was also superior to prostaglandin in lowering blood urea nitrogen (BUN), creatinine clearance rate (Ccr). There were no adverse effects reported in the trials from astragalus injection. Conclusions. Astragalus injection showed protective effects in hypertensive renal damage patients, although available studies are not adequate to draw a definite conclusion due to low quality of included trials. More rigorous clinical trials with high quality are warranted to give high level of evidence.

Cardiovascular and Renal Links along the Cardiorenal Continuum

The cardiorenal syndrome includes the widely known relationship between kidney function and cardiovascular disease. A large number of patients have various degrees of heart and kidney dysfunction worldwide, both in developed and developing countries. Disorders affecting one of them mostly involve the other. Such interactions represent the pathogenesis for a clinical condition called cardiorenal syndrome. Renal and cardiovascular disease shares similar etiologic risk factors. The majority of vascular events are caused by accelerated atherosclerosis. Moreover, cardiovascular events rarely occur in patients without underlying disease; rather, they typically take place as the final stage of a pathophysiological process that results in progressive vascular damage, including vital organ damage, specifically the kidney and the heart if these factors are uncontrolled. Chronic kidney disease is a novel risk factor included at this stage that accelerates both vascular and cardiac damage.

Renal and cardiac abnormalities in primary hypertension

OBJECTIVE

The relationship between mild reduction in renal function and cardiac structure and function have not yet been fully elucidated. We investigated cardiac and renal abnormalities in 400 untreated, nondiabetic patients (65% men, mean age 47 years) with primary hypertension and normal serum creatinine.

METHODS

Renal abnormalities were defined as creatinine clearance less than 75 ml/min per 1.73 m2 (Cockcroft-Gault formula) and/or the presence of microalbuminuria (albumin-to-creatinine ratio). Left ventricular structure and function were assessed by echocardiography.

RESULTS

The prevalence of microalbuminuria and reduced creatinine clearance was 13 and 31%, respectively. Patients with renal abnormalities shared greater left ventricular mass index, higher prevalence of left ventricular hypertrophy, and unfavorable geometric patterns. Microalbuminuria was also associated with inappropriate left ventricular mass and depressed midwall fractional shortening, whereas reduced creatinine clearance was associated with lower stroke volume and higher central pulse pressure/stroke volume ratio and total peripheral resistance. Stepwise regression analysis showed that both albuminuria and creatinine clearance were independently related to left ventricular mass. Logistic regression analysis of the reciprocal interaction of microalbuminuria and reduced creatinine clearance on the occurrence of subclinical cardiac damage showed that reduced creatinine clearance entailed a greater risk of left ventricular hypertrophy in patients with normal albuminuria alone, whereas the presence of microalbuminuria was associated with a greater risk of left ventricular hypertrophy independently of creatinine clearance.

CONCLUSIONS

These findings provide further proof of the role of cardiorenal interaction in the development of hypertension-related cardiovascular disease, and may have clinical implications.

The renoprotective effects of RAS inhibition: focus on prevention and treatment of chronic kidney disease

Chronic kidney disease (CKD) shares major risk factors with cardiovascular disease(CVD), including hypertension and diabetes mellitus. In patients with hypertensive kidney disease and diabetic nephropathy, inhibitors of the renin-angiotensin system (RAS) significantly reduce the risk of renal and cardiovascular endpoints. Whether the renoprotective effects of RAS inhibitors can be fully accounted for by blood pressure reductions or whether other mechanisms are involved has not been clearly established. Because RAS inhibitors reduce albuminuria and slow progression of kidney disease, they are recommended as fi rst-line antihypertensive agents in patients with CKD, who often require aggressive treatment with > or = 2 drugs to reach the goal blood pressure (< 130/80 mm Hg). Greater RAS inhibition with higher-than-usual doses of a single agent or dual RAS inhibition with an angiotensin-converting enzyme inhibitor and an angiotensin receptor blocker may be necessary for maximum renoprotective effects. Ongoing clinical trials assessing treatment and prevention of CKD may resolve unanswered questions about RAS inhibition in patients with hypertension and/or diabetes.

Coronary flow reserve is impaired in hypertensive patients with subclinical renal damage

BACKGROUND

Renal dysfunction is relatively common in patients with primary hypertension (PH). A reduction in coronary vasodilator capacity has recently been reported in patients with renal damage undergoing coronary angiography. We investigated the relationship between coronary flow reserve (CFR) and early renal abnormalities in patients with PH and normal serum creatinine.

METHODS

Seventy-six untreated patients were studied. Albuminuria was measured as the albumin-to-creatinine ratio and glomerular filtration rate (eGFR) was estimated by the Cockroft-Gault formula. Chronic kidney disease (CKD) was defined as an eGFR <60 ml/min/1.73 m(2) and/or in the presence of microalbuminuria. Coronary blood flow velocities (cm/s) were measured by Doppler ultrasound at rest and after adenosine administration. CFR was defined as the ratio of hyperemic-to-resting diastolic peak velocities.

RESULTS

Prevalence of reduced eGFR, microalbuminuria, CKD, and left ventricular (LV) hypertrophy was 8, 10, 16, and 31%, respectively. Overall, 10% of patients showed impaired CFR (i.e., <2.0). Patients with CKD were more likely to be older (P < 0.05) and of female gender (P < 0.01) and showed higher LV mass index (LVMI) (P < 0.05), lower CFR (P < 0.05; analysis of covariance, P < 0.05), and CFR/LVMI (P < 0.05) than patients with normal renal function. Conversely, patients with impaired CFR showed a significantly higher prevalence of reduced eGFR (chi(2) 5.2, P < 0.05), microalbuminuria (chi(2) 10.2, P < 0.01), and CKD (chi(2) 9.2.1, P < 0.01). Even after adjustment for gender, the presence of CKD entailed a sevenfold higher risk of having impaired CFR (confidence interval 1.17-40.9, P < 0.05).

CONCLUSION

Early renal abnormalities are associated with reduced CFR in PH.

Global risk stratification in primary hypertension: the role of the kidney

OBJECTIVE

Microalbuminuria and a reduction in creatinine clearance are well known, independent predictors of unfavourable cardiovascular prognosis. Our aim was to evaluate the impact of renal damage on global risk stratification in 459 non-diabetic, untreated hypertensive patients (64% men, mean age 47.3 years).

METHODS

Renal damage was defined as creatinine clearance < 60 ml/min per 1.73 m2 (Cockcroft-Gault formula) or the presence of microalbuminuria (albumin to creatinine ratio). Cardiac and vascular organ damage was assessed by ultrasound scan. We evaluated the impact of renal damage, left ventricular hypertrophy and carotid atherosclerosis on risk stratification as recommended by the 2007 European Society of Hypertension-European Society of Cardiology Guidelines.

RESULTS

The prevalence of renal damage, microalbuminuria and creatinine clearance < 60 ml/min per 1.73 m2 was 24, 12 and 13%, respectively. There was no correlation between albuminuria and estimated creatinine clearance, and only 0.9% of patients showed microalbuminuria and reduced creatinine clearance simultaneously. The presence of renal damage entailed a 3.3 times higher risk of having cardiovascular abnormalities. Based on routine work-up, 58% of our study patients were classified as high-very high risk. The simultaneous evaluation of albuminuria and creatinine clearance resulted in a significant change in risk stratification, since 68% of patients were classified in the high-very high risk class. The search for left ventricular hypertrophy or carotid atherosclerosis by ultrasonography did not improve risk stratification significantly as compared to the assessment of renal damage.

CONCLUSIONS

Our findings support the assessment of renal abnormalities as the first step when evaluating target organ damage for cardiovascular risk assessment in hypertensive patients.

Treatment of microalbuminuria in hypertensive subjects with elevated cardiovascular risk: Results of the IMPROVE trial

Microalbuminuria independently predicts increased cardiovascular risk in hypertensive patients, especially in those with concomitant diabetes or established cardiovascular disease. Drugs that target the renin-angiotensin-aldosterone system reduce microalbuminuria regardless of diabetic status. The Irbesartan in the Management of PROteinuric patients at high risk for Vascular Events was a multicenter, randomized, double-blind, placebo-controlled paralleled group study in which hypertensive patients with microalbuminuria and increased cardiovascular risk were randomized to 20 weeks treatment with ramipril plus irbesartan or to ramipril plus placebo. Patients discontinued or tapered previous antihypertensive therapy during a 14-day placebo lead-in period. Change in albumin excretion rate from baseline to week 20 was the primary end point. Adjusted week 20 baseline geometric ratios for ramipril plus irbesartan and ramipril plus placebo were not significantly different. Although differences in blood pressure reductions were observed between the two treatments, these changes did not affect microalbuminuria. More patients on dual therapy achieved target blood pressure goals at week 20 than with monotherapy. The incidence of adverse effects and treatment-related adverse effects was similar in both groups. Our results suggest that patients with cardiovascular risk and relatively low albumin excretion rates in early-stage disease may only require monotherapy with renin-angiotensin-aldosterone blocking agents.

Uric acid and other renal function parameters in patients with stable angina pectoris participating in the ACTION trial: impact of nifedipine GITS (gastro-intestinal therapeutic system) and relation to outcome

BACKGROUND

Little data is available concerning the prognostic implications of renal function abnormalities, their evolution over time and the effects of nifedipine on such abnormalities in patients with stable angina pectoris.

METHODS

The previously published ACTION trial compared long-acting nifedipine GITS 60 mg once daily to placebo among 7,665 patients. Standard laboratory tests including creatinine and uric acid were assessed at baseline, after 6 months, 2 and 4 years, and at the end of follow-up. We assessed the impact of nifedipine on markers of renal dysfunction and determined whether evidence of renal failure alters the impact of nifedipine on the clinical outcome of patients with stable angina.

RESULTS

Uric acid was not while creatinine level and estimated creatinine clearance were potent conditionally independent predictors of total mortality and of cardiovascular clinical events. Relative to placebo, nifedipine reduced 6-month uric acid levels by 3% (P < 0.001) of the baseline value. This difference was maintained during long-term follow-up, was present both in normotensives and in hypertensives, and was not explained by differences in diuretic therapy or allopurinol use. Nifedipine had no effect on the occurrence of clinical renal failure. Relative to placebo, the effects of nifedipine on cardiovascular death or myocardial infarction [hazard ratio (HR) = 1.01, 95% confidence interval (CI) 0.88-1.17], any stroke or transient ischaemic attack (HR = 0.73, 95% CI 0.60-0.88), new overt heart failure (HR = 0.72, 95% CI 0.55-0.95), and the need for any coronary procedure (HR = 0.81, 95% CI 0.75-0.88) were consistent across strata of markers of renal dysfunction.

CONCLUSIONS

We conclude that, in patients with stable angina, nifedipine reduces uric acid levels and does not affect other markers of renal dysfunction. Renal dysfunction does not alter the effects of nifedipine on clinical outcome.

Impact of telmisartan versus ramipril on renal endothelial function in patients with hypertension and type 2 diabetes

OBJECTIVE

One of the earliest signs of vascular change is endothelial dysfunction, which is also known to provoke albuminuria and to predict cardiovascular prognosis. The aim of this study was to analyze the effects of renin-angiotensin system (RAS) blockade on renal endothelial function.

RESEARCH DESIGN AND METHODS

In a multicenter, prospective, double-blind, forced-titration, randomized study, 96 patients with type 2 diabetes, hypertension, glomerular filtration rate >80 ml/min, and normo- or microalbuminuria were treated once daily with 40/80 mg telmisartan or 5/10 mg ramipril for 9 weeks.

RESULTS

The mean +/- SE fall in renal plasma flow (RPF) in response to intravenous N(G)-monomethyl-L-arginine (L-NMMA), reflecting the magnitude of nitric oxide (NO) activity, increased with telmisartan from 71.9 +/- 9.0 ml/min before therapy to 105.2 +/- 9.7 ml/min at the end of treatment (P < 0.001). With ramipril, RPF response to L-NMMA increased from 60.1 +/- 12.2 to 87.8 +/- 9.2 ml/min (P = 0.018). The adjusted difference between treatments was -17.1 +/- 13.7 ml/min (P = 0.214). In accordance, telmisartan increased RPF at rest (i.e., without L-NMMA) from 652.0 +/- 27.0 to 696.1 +/- 31.0 ml/min (P = 0.047), whereas ramipril produced no significant changes in RPF. The more the basal NO activity improved, the greater was the vasodilatory effect on renal vasculature (r = 0.47, P < 0.001).

CONCLUSIONS

In patients with type 2 diabetes, telmisartan and ramipril both increased NO activity of the renal endothelium significantly, which in turn may support the preservation of cardiovascular and renal function.

Ambulatory arterial stiffness index and renal abnormalities in primary hypertension

OBJECTIVE

Arterial stiffness is a predictor of cardiovascular mortality in the general population as well as in hypertension and end-stage renal disease. We investigated the relationship between a recently proposed ambulatory blood pressure monitoring-derived index of arterial stiffness and early signs of renal damage in patients with primary hypertension.

DESIGN AND SETTING

A total of 168 untreated patients with sustained primary hypertension were studied. Ambulatory arterial stiffness index (AASI) was calculated based on 24-h ambulatory blood pressure readings. Albuminuria was measured as the albumin to creatinine ratio. Creatinine clearance was estimated using the Cockcroft-Gault formula, and the interlobar resistive index was evaluated by renal ultrasound and Doppler examination.

RESULTS

AASI was positively related to urinary albumin excretion and resistive index, and was negatively related to estimated creatinine clearance and renal volume to the resistive index ratio. Patients with AASI above the median (i.e. > 0.51) showed a higher prevalence of microalbuminuria and a mild reduction in creatinine clearance. Moreover, patients with microalbuminuria or a mild reduction in creatinine clearance had significantly higher AASI values compared with those without, and the greater the renal involvement, the greater the AASI. After adjusting for several potentially confounding variables, we found that each standard deviation increase in AASI (i.e. 0.16) entails an almost twofold greater risk of renal involvement.

CONCLUSION

Increased AASI is independently associated with early signs of renal damage in patients with sustained primary hypertension. These results strengthen the usefulness of AASI and ambulatory blood pressure monitoring in cardiovascular risk assessment.

Rationale and design of a study to evaluate management of proteinuria in patients at high risk for vascular events: the IMPROVE trial

Declining kidney function predicts increasing cardiovascular risk in people with hypertension. Microalbuminuria is a marker for cardiovascular risk and declining kidney function. Agents that block the renin-angiotensin-aldosterone system (RAAS), notably angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), reduce proteinuria and microalbuminuria, lower blood pressure and slow the progression of proteinuric kidney disease. Evidence is accumulating that the combination of an ACE inhibitor and an ARB is the optimal means of RAAS blockade in this setting, slowing the progression of nephropathy independently of blood pressure lowering to a greater degree than can be achieved using maximum approved doses of either agent alone. However, the emerging therapeutic potential of ACE inhibitor/ARB combination therapy in hypertensive kidney disease requires further characterization. The Irbesartan in the Management of PROteinuric patients at high risk for Vascular Events trial aims to determine definitively whether the combination therapy of an ARB, irbesartan and an ACE inhibitor, ramipril, is more effective than ramipril alone in reducing the urinary albumin excretion rate in patients at high cardiovascular risk with hypertension and proteinuria or microalbuminuria.

Vascular diseases and their risk factors in IgA nephropathy

BACKGROUND

Many studies have focused on risk factors for renal insufficiency in IgA nephropathy (IgAN). We recently found metabolic factors, especially uric acid, to predict progression and marked histopathological lesions in IgAN. Since vascular diseases (VDs), in addition to renal insufficiency, affect the overall survival of IgAN patients, we studied the occurrence of and risk factors underlying VDs in IgAN.

METHODS

In this study, VDs here comprised the presence of coronary heart disease (CHD) and/or cerebrovascular disease (CeVD). We correlated clinical, metabolic and histopathological findings with the occurrence of VDs in 221 adult patients with IgAN. Seven histopathological parameters were semiquantitatively graded. Logistic regression analysis was used to evaluate independent predictors of VDs in these patients. The occurrence of VDs in IgAN patients > or = 30 years of age was studied and compared with that in the general population drawn from the same area.

RESULTS

VDs were notably common in IgAN patients. Patients with IgAN had significantly more frequent VDs, CHD and CeVD than the general population (P < 0.01 to < 0.001). Of > or = 30 years of age IgAN patients, 25% had some VD at the end of follow-up, while only 9% of the general population had VDs [odds ratio, OR 4.6 (2.2-9.4)]. Old age, male gender, hypertension, proteinuria, renal insufficiency, hyperuricaemia, hypertriglyceridaemia, diabetes, smoking and high body mass index correlated with the occurrence of VDs in univariate analysis. In all patients initial renal insufficiency and smoking were independently associated with some VD, male gender with CHD and hypertension with CeVD. In the multivariate analysis model including patients with initially normal renal function, male gender was independently associated with some VD, and hypertriglyceridaemia with CHD.

CONCLUSION

VDs, especially CeVD, would seem to be particularly common in patients with IgAN. Patients with progressive renal disease run a significantly elevated risk of developing VD. Many previously known risk factors for VD were also associated with the occurrence of some VD in the present study. Vascular changes seen in renal biopsy in patients with IgAN signify an elevated risk of VDs.

Relation of urinary albumin excretion to coronary heart disease and low renal function: Role of blood pressure

BACKGROUND

Previous studies report that urinary albumin excretion is associated with coronary heart disease (CHD). The present epidemiologic study investigated if (1) blood pressure status affects the association of urinary albumin excretion with CHD; and (2) urinary albumin excretion is associated with low renal function also.

METHODS

The cross-sectional association was analyzed of overnight urinary albumin excretion with prevalence of CHD (myocardial infarction and/or ischemia as defined by standard electrocardiogram) and low renal function (overnight creatinine clearance <60 mL/min) in a population sample of 1632 men and women with ages 45 to 64 years. Hypertension, hypercholesterolemia, smoking habit, and diabetes mellitus were included in analyses.

RESULTS

CHD prevalence was in the whole sample 8.2% (N= 134), in the hypertensive subgroup 11.9% (N= 79), and in the nonhypertensive subgroup 5.7% (N= 55). For the association between urinary albumin excretion (logarithm-transformed due to skewed distribution) and CHD, the multivariate logistic coefficient with 95% CI was significant in the whole sample (+0.79, 95% CI =+0.32/+1.26, P < 0.001) and in the hypertensive subgroup (+0.97, 95% CI =+0.70/+1.24, P < 0.001), not in the nonhypertensive subgroup (-0.06, 95% CI =-0.80/+0.68, P= 0.997). Prevalence of low creatinine clearance was in the whole sample 4.0% (N= 66), in the hypertensive subgroup 4.8% (N= 32), and in the nonhypertensive subgroup 3.5% (N= 34). The logistic coefficient between urinary albumin excretion and low creatinine clearance was borderline significant in the whole sample (+0.56, 95% CI =-0.02/+1.14, P= 0.090), significant in the hypertensive subgroup (+0.73, 95% CI =+0.04/+1.42, P= 0.044), not significant in the nonhypertensive subgroup (-0.07, 95% CI =-1.25/+1.10, P= 0.913).

CONCLUSION

Results support the use of urinary albumin excretion as marker of CHD and slightly reduced renal function in hypertensives.

How to titrate ACE inhibitors and angiotensin receptor blockers in renal patients: according to blood pressure or proteinuria?

The inhibition of the effects of angiotensin II is necessary to ensure the best degree of renal protection by the simultaneous control of blood pressure (BP) and the achievement of the maximal antiproteinuric capacity. The inhibition can be attained through the administration of either an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin II receptor blocker (ARB). Uptitration of antihypertensive therapy is frequently required to achieve the desired BP goal in patients presenting with renal disease, with or without proteinuria. Control of BP is good for both cardiovascular and renal protection. Sometimes, in particular when BP levels are high in the absence of therapy, the simple control of BP without inhibiting the renin- angiotensin system can be accompanied by a significant drop in proteinuria. On the other hand, the possibility that an ACE inhibitor or an ARB diminishes protein excretion in urine in the absence of changes in BP has been considered after the known evidence that these classes of drugs are renoprotective independently of their effect on BP control. The aim of this paper is to briefly review the evidence in favor of uptitration of either class of inhibitors of the renin-angiotensin system as compared with the combination of the two for the control of either BP or proteinuria.