Renal and systemic transvascular albumin leakage in severe atherosclerosis

Transcapillary escape rate of 125I-albumin in relation to timing of blood sampling: the need for standardization

Background

Increased vascular permeability is an early sign of vascular damage and can be measured with the transcapillary escape rate of albumin (TER_alb). Although TER_alb has a multi-exponential kinetic model, most published TER_alb data are based on mono-exponential kinetic models with variation in blood sampling schemes. Aim of this posthoc study was to evaluate the influence of variation in blood sampling schemes and the impact of mono- or bi-exponential analyses on the calculation of TER_alb. Study participants were part of a cross-over intervention study protocol, investigating effects of sodium loading on blood pressure, endothelial surface layer and microcirculation. Multiple blood samples were drawn between 3 and 60 min after injection of radioactive iodide labeled human serum albumin (rHSA).

Results

In total 27 male participants with 54 measurements were included. For all participants the maximum serum radioactivity was reached within 20 min, while 85% of the participants had their maximum serum activity within 10 min. The TER_alb calculated with the subsequently chosen T_{20–60 min} reference scheme (6.19 ± 0.49%/h) was significantly lower compared to the TER_alb of the T_{3–60 min}, T_{5–60 min}, and T_{max – 60 min} schemes. There was no significant difference between the T_{20–60 min} reference scheme and the T_{10–60 min} and T_{15–60 min} schemes. Bi-exponential kinetic modeling did not result in significant different observations compared to the mono-exponential kinetic analysis.

Conclusions

As there is variation in the timing of the maximum serum radioactivity of rHSA, blood sampling schemes starting before 10 min after administration of rHSA will result in a significant overestimation of TER_alb. In addition, variation in kinetic modeling did not result in significant changes in TER_alb. Therefore, we emphasize the need to standardize TER_alb and for practical and logistical reasons advocate the use of a mono-exponential model with blood sampling starting 20 min after rHSA administration.

Renal outcomes and blood pressure patterns in diabetic and nondiabetic individuals at high cardiovascular risk

BACKGROUND

Diabetes and hypertension are risk factors for renal and cardiovascular outcomes. Data on the association of achieved blood pressure (BP) with renal outcomes in patients with and without diabetes are sparse. We investigated the association of achieved SBP, DBP with renal outcomes and urinary albumin excretion (UAE) in people with vascular disease.

METHODS

In this pooled analysis, we assessed renal outcome data from high-risk patients aged 55 years or older with a history of cardiovascular disease, 70% of whom had hypertension, randomized to The Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial and to Telmisartan Randomized Assessment Study in ACE Intolerant Subjects with Cardiovascular Disease trials investigating telmisartan, ramipril and their combination with a median follow-up of 56 months. Standardized office BP was measured every 6 months, estimated glomerular filtration rate (eGFR) and UAE at baseline, 2 years and study end. Associations of mean achieved BP on treatment were investigated on major renal outcomes including end-stage renal disease (ESRD), decline of eGFR by at least 40%, doubling of creatinine and the composites thereof and on UAE. Analyses were by Cox regression analysis, analysis of variance and Chi2-test. Of 30 937 patients with complete data, 19 450 patients without and 11 487 with diabetes were enrolled between 1 December 2001 and 31 July 2003 and followed until 31 July 2008. Data were pooled as the outcomes for telmisartan 80 mg/day (n = 2903) or placebo (n = 2907) for Telmisartan Randomized Assessment Study in ACE Intolerant Subjects with Cardiovascular Disease and ramipril 10 mg/day (n = 8407), telmisartan 80 mg/day (n = 8386) or the combination of both (n = 8334) were similar.

RESULTS

For both those with and without diabetes, the hazard ratios for the composites ESRD or doubling of serum creatinine (707 events overall) and ESRD or 40% eGFR loss (2371 events overall) reached a nadir at achieved SBP of 120 to less than 140 mmHg, and increased with higher and lower SBP with similar relative risk with or without diabetes. For example, risk for the former composite reached a hazard ratios 3.06 (confidence interval 1.90-4.92) with a mean achieved SBP more than 160 mmHg compared with 120 to less than 130 mmHg with diabetes and hazard ratios 2.14 (1.09-4.26) without diabetes. In contrast, the development of new microalbuminuria and macroalbuminuria (3002 and 846 events overall) associated linearly over the whole range of achieved SBP (apart from a slight increase in risk at SBP less than 120 mmHg only in those without diabetes). Absolute risks for the composite and albuminuria outcomes were consistently greater in those with diabetes as compared with without diabetes with high event rates over the whole SBP spectrum. The increased renal risk at low SBP was not related to a meaningful reduction of mandated study drugs or open label renin-angiotensin-aldosterone system inhibition.

CONCLUSION

In patients at high cardiovascular risk, SBP levels more than 140 mmHg and less than 120 are associated with increased risk for renal outcomes. Renal risk was greater in diabetes across the whole range of achieved SBP and DBP. These data suggest similar target BP range in patients with and without diabetes to prevent renal outcomes, a frequent complication in high-risk vascular patients.

CLINICAL TRIAL REGISTRATION

Clinical Trial registration: http://clinicaltrials.gov.Unique identifier: NCT00153101.

Longitudinal association of carotid endothelial shear stress with renal function decline in aging adults with normal renal function: A population-based cohort study

The aim of this study was to investigate the associations between carotid wall shear stress (WSS) and renal function impairment (RFI) and albuminuria in aging adults. A total of 1,447 subjects aged 60 years and older with normal estimated glomerular filtration rate (eGFR ≥ 60 mL·min-1·1.72 m-2) and albumin/creatinine ratio (ACR < 30 mg·g-1) were enrolled between April 2007 and October 2009 in the Shandong area, China. Carotid WSS was assessed at baseline, and eGFR, which is based on serum creatinine and cystatin C, and ACR were assessed at baseline and at the annual follow-up visits. After an average of 62.9 months of follow-up, the reduction in eGFR and the increase in ACR were significantly higher in the Q1+2+3 group than the Q4 group, as classified by either the interquartile of the mean WSS or the interquartile of the peak WSS after adjustment for multi-variabilities, including the average blood pressures at every annual visit and baseline eGFR and ACR. For groups classified by mean WSS, the hazard ratios (95% confidence intervals) were 3.45 (1.36-8.75, p = 0.008) in the incident RFI and 3.24 3.22 (1.37-7.57, p = 0.009) in the incident albuminuria for the Q1+2+3 group compared with the Q4 group. Similar results were observed among groups classified by peak WSS. The Q1+2+3 group was associated with endothelial dysfunction and inflammation with respect to the Q4 group as classified by mean or peak WSS. The results indicate that carotid WSS plays an important role in RFI and albuminuria progression in aging adults. Lower WSS was associated with a higher risk of RFI and albuminuria compared with higher WSS.

Deletion of endothelial cell-specific liver kinase B1 increases angiogenesis and tumor growth via vascular endothelial growth factor

Liver kinase B1 (LKB1) is a serine/threonine protein kinase ubiquitously expressed in mammalian cells. It was first identified in Peutz-Jeghers syndrome as a tumor suppressor gene. Whether endothelial LKB1 regulates angiogenesis and tumor growth is unknown. In this study, we generated endothelial cell-specific LKB1-knockout (LKB1^endo−/−) mice by crossbreeding vascular endothelial-cadherin-Cre mice with LKB1^flox/flox mice. Vascular endothelial growth factor (VEGF) level was highly co-stained in endothelial cells but not macrophages in LKB1^endo−/− mice. Consistently, LKB1^endo−/− mouse tissues including the lung, skin, kidney, and liver showed increased vascular permeability. Tumors implanted in LKB1^endo−/− mice but not macrophage-specific LKB1-knockout mice grew faster and showed enhanced vascular permeability and increased angiogenesis as compared with those implanted in wild-type mice. Injection of VEGF-neutralizing antibody but not the isotype-matched control antibody decreased endothelial-cell angiogenesis and tumor growth in vivo. Furthermore, LKB1 deletion enhanced mouse retinal and cell angiogenesis, and knockdown of VEGF by small-interfering RNA decreased endothelial cell proliferation and migration. Re-expression of LKB1 or knockdown of VEGF receptor 2 decreased the over-proliferation and -migration observed in LKB1^endo−/− cells. Mechanistically, LKB1 could bind to the VEGF transcription factor, specificity protein 1 (Sp1), which then inhibited the binding of Sp1 to the VEGF promoter to reduce VEGF expression. Endothelial LKB1 may regulate endothelial angiogenesis and tumor growth by modulating Sp1-mediated VEGF expression.

Urinary Albumin Excretion Reflects Cardiovascular Risk in Postmenopausal Women without Diabetes: The 2011 to 2013 Korean National Health and Nutrition Examination Survey

BACKGROUND

The objective of the current study was to determine whether there was an association between urinary albumin excretion and cardiovascular disease (CVD) risk by estimating the Framingham Risk Score (FRS) in postmenopausal women without diabetes.

METHODS

This study was based on data from the Korea National Health and Nutrition Examination Survey, which was conducted by the Korean Ministry of Health and Welfare in 2011 to 2013. Data on 2,316 postmenopausal women from a total of 24,594 participants was included in the analysis.

RESULTS

The mean FRS was significantly different in each of the urinary albumin to creatinine ratio (UACR) subgroups, and it increased with UACR. The FRS was 12.69±0.12 in the optimal group, 14.30±0.19 in the intermediate normal group, 14.62±0.26 in the high normal group, and 15.86±0.36 in the microalbuminuria group. After fully adjusting for potential confounding factors, high normal levels and microalbuminuria were significantly associated with the highest tertile of FRS ([odds ratio (OR), 1.642; 95% confidence interval (CI), 1.124 to 2.400] and [OR, 3.385; 95% CI, 2.088 to 5.488], respectively) compared with the optimal subgroup. High normal levels and microalbuminuria were also significantly associated with a ≥10% 10-year risk of CVD ([OR, 1.853; 95% CI, 1.122 to 3.060] and [OR, 2.831; 95% CI, 1.327 to 6.037], respectively) after adjusting for potential confounding covariates.

CONCLUSION

Urinary albumin excretion reflects CVD risk in postmenopausal women without diabetes, and high normal levels and microalbuminuria were independently associated with a higher risk of CVD.

Association of heart rate with albuminuria in a general adult population: the 2011 Korea National Health and Nutrition Examination Survey

BACKGROUND

Albuminuria is associated with increased risk of multiple adverse health outcomes, such as progressive renal failure, cardiovascular disease and death. However, in the general population, it is uncertain whether albuminuria is associated with elevated heart rate, which is an independent and powerful risk factor for cardiovascular disease.

AIM

To investigate whether an elevated heart rate is an independent factor associated with albuminuria in the general adult population of Korea.

METHODS

A cross-sectional analysis was carried out on 5198 Korean adults aged 19 years or older who participated in the fifth (2011) Korea National Health and Nutrition Examination Survey (KNHANES V-2).

RESULTS

The prevalence of albuminuria showed an increasing trend throughout the whole range of heart rate, even after adjusting for confounders (P = 0.002). The increment was most profound at the heart rate of 70-75 and >76 beats per minute (b.p.m.; P = 0.011). In multiple logistic regression analysis, age (P < 0.001), hypertension (P < 0.001), diabetes (P < 0.001), hypertriglyceridaemia (P = 0.025), estimated glomerular filtration rate (P = 0.028) and heart rate (P = 0.023) were independently associated with the presence of albuminuria in Korean adults. Compared with participants with heart rate ≤ 64 b.p.m., the odds ratio (95% CI) for albuminuria was 1.50 (1.15-1.96) for those with heart rate ≥ 76 b.p.m.

CONCLUSIONS

The prevalence of albuminuria is independently associated with heart rate in the general adult population of Korea.

Microalbuminuria in non-diabetic patients with unstable angina/non ST-segment elevation myocardial infarction

BACKGROUND

Microalbuminuria (MAU) is defined as an urinary albumin excretion rate between 20-200 mg/l or 30-300 mg/day. It is a surrogate marker for endothelial dysfunction and is independently associated with atherosclerotis in diabetic and in non-diabetic patients. We assessed the prevalence of MAU in non-diabetic patients who presented with UA/NSTEMI and the relation of MAU to the severity of coronary artery disease in patients at a cardiac care center in Iraq.

METHODS

Seventy non-diabetic patients referred to the Iraqi Center for Heart Disease, Baghdad, between November 1st 2010 and June 1st 2011 with the diagnosis of UA/NSTEMI were included in this study. Physical examination, ECG and echocardiography were performed on all patients. TIMI ("Thrombolysis in Myocardial Infarction") risk score was obtained. Urine samples were collected and sent for quantitative determination of MAU. All patients underwent diagnostic coronary angiography. Data are give as mean (quantitative and percent) ± SD.

RESULTS

Fifty-three men (76%) and 17 (24%) women (mean age 56 ± 12 years) were investigated. Overall 37 (53%) individuals presented with arterial hypertension and 41 (59%) with a history of smoking. 58 patients (83%) had ischemic ECG changes (defined as ST segment depression more than 1 mm from baseline, and/or T wave inversion), 52 (74%) had echocardiographic findings indicative of ischemia (defined as segmental wall motion abnormalities). Twenty-one (30%) patients tested positive for MAU. There was a significant correlation of echocardiographic signs of ischemia and MAU, (n = 20 (38%), p < 0.01). There was a clear relationship between MAU and TIMI risk score. Additionally, MAU was more common in patients with multivessel coronary artery disease (CAD) (p < 0.001). There was no statistically significant correlation between MAU and mean age, sex, smoking, and blood pressure.

CONCLUSION

In this analysis of patients with UA/NSTEMI we found a strong correlation of microalbuminuria with echocardiographic changes and findings in coronary angiography.

Plasma albumin and platelet function: relevance to atherogenesis and thrombosis

Two papers published in this journal(1,2) during the past year remind us that plasma albumin concentrations can influence platelet function. These publications, together with epidemiological evidence showing that low plasma concentrations of albumin predict mortality from cardiovascular disease(3,4) have prompted this review.

Hypoalbuminaemia, systemic albumin leak and endothelial dysfunction in peritoneal dialysis patients

BACKGROUND

Inflammation, hypoalbuminaemia and peritoneal protein clearance are important predictors of survival in patients treated with peritoneal dialysis (PD). We hypothesized that the common link is abnormal endothelial barrier function. To test this, we explored associations between hypoalbuminaemia, systemic albumin leak and soluble markers of systemic inflammation and endothelial injury.

METHODS

This was a cross-sectional study of 41 prevalent PD patients. Endothelial barrier function was measured as transcapillary escape rate of (125)I albumin [transcapillary escape rate of albumin (TER(alb))]. Seventeen plasma biomarkers including pro-inflammatory cytokines, endothelial biomarkers and metalloproteinases were measured. Hierarchical clustering analysis (HCA) and principal component analysis (PCA) were used to explore the hypothesis.

RESULTS

The mean TER(alb) was 13.7 ± 8.9 (%/h), higher than in non-uraemic subjects 8.22 ± 5.8 (%/h). Three patient clusters were defined from HCA according to their biomarker patterns. Cluster 1 was characterized by inflammation, hypoalbuminaemia, overhydration and intermediate TER(alb). Cluster 2 was non-inflamed, preserved muscle mass and more normal TER(alb). Cluster 3 had highest TER(alb), platelet activation, preserved plasma albumin and intermediate high-sensitivity C-reactive protein levels. Two principal components (PCs) were identified from the biomarker matrix, PC1, indicating platelet activation and PC2, pro-inflammatory. TER(alb) was positively related to PC1 but not PC2. Diabetes and ischaemic heart disease were associated with PC1 and PC2, respectively.

CONCLUSIONS

This exploratory analysis indicates that endothelial barrier function is decreased in PD patients and is associated with diabetic status and markers of platelet activation more than inflammation. In contrast, hypoalbuminaemia is associated more with inflammation and atherosclerotic disease indicating a more complex relationship between systemic endothelial barrier function, inflammation and hypoalbuminaemia which requires further validation.

The relationship between renal impairment and left ventricular structure, function, and ventricular-arterial interaction in hypertension

OBJECTIVES

Our objective was to define the relationship between renal dysfunction--both albuminuria and reduced estimated glomerular filtration rate (eGFR)--and cardiac structure and diastolic dysfunction among patients with chronic hypertension.

METHODS

Both albuminuria and eGFR were measured in 540 asymptomatic patients with hypertension and diastolic dysfunction assessed by reduced early mitral annular relaxation velocity (E'). The majority of patients were white, mean age was 60 ± 10 years, mean SBP was 149 ± 18 mmHg, and there was a low prevalence comorbid conditions. Albuminuria was undetectable in 148 (27%), within the normal to low range [urine albumin-to-creatinine ratio (UACR) 1-25 mg/g for men, 1-17 mg/g for women] in 292 (54%), and high or very high (UACR >25 mg/g for men, >17 mg/g for women) in 100 (19%). Estimated GFR was 60 ml/min per 1.73 m² or less in 75 (14%), 61-90 ml/min per 1.73 m² in 244 (45%), and more than 90 ml/min per 1.73 m² in 221 (41%).

RESULTS

Albuminuria, even within the normal range, was associated with greater left ventricular wall thickness (P = 0.01), higher relative wall thickness (P = 0.004), worse diastolic function reflected in lower E' (P = 0.01), greater arterial and left ventricular end-systolic stiffness (P < 0.0001 and P = 0.003, respectively), and higher N-terminal pro-brain natriuretic peptide (NT-proBNP) level (P = 0.0025), even after adjustment for differences in baseline characteristics. In contrast, no independent relationship was observed between eGFR and parameters of cardiac structure or function.

CONCLUSION

Among asymptomatic hypertensive patients with evidence of diastolic dysfunction, the presence of albuminuria, even within the normal range, is associated with greater concentric remodeling, greater left ventricular end-systolic stiffness, and worse diastolic function.

Clinical characteristics, cardiac events and coronary angiographic findings in the prospective PREVEND cohort: an observational study

BACKGROUND

The use of invasive procedures has mostly been studied in retrospective (multi)- national registries. Limited evidence exists on the association between microalbuminuria and coronary artery disease (CAD).

METHODS

The incidence of major adverse cardiac events (MACE) and invasive cardiac procedures was registered between 1997 and 2003 in 8139 subjects, without prior documented CAD, in the PREVEND cohort study (the Netherlands), in which the focus is on microalbuminuria and cardiovascular risk. Qualitative coronary angiographic analysis was performed.

RESULTS

During 5.5 years of follow-up, a first MACE occurred in 271 (3.3%) and a first coronary angiography (CAG) was performed in 264 (3.2%) subjects. Of these, 216 CAGs were available for qualitative angiographic analysis. Indications for CAG were stable angina in 129, acute coronary syndrome (ACS) in 55 and ST-elevation myocardial infarction (STEMI) in 32 subjects. Obstructive coronary artery disease was present in 61, 53 and 30 subjects, respectively. A revascularisation was performed in 50 (39%), 50 (91%) and 25 (78%) subjects, respectively. Microalbuminuria was associated with a first MACE, after adjustment for established risk factors. Microalbuminuria was present at baseline in 9% of subjects with normal coronary arteries, in 21% of subjects with one- and two-vessel CAD and in 39% of subjects with threevessel or left main CAD at CAG during follow-up (Ptrend=0.005).

CONCLUSION

This large cohort study shows that two-thirds of diagnostic CAGs for stable angina were not followed by a revascularisation, in contrast to CAGs for STEMI or ACS. Furthermore, this study shows that microalbuminuria is associated with CAD. (Neth Heart J 2007;15:133-41.).

The relation between microalbuminuria and coronary collateral vessel development in patients with unstable coronary artery disease

Microalbuminuria, considered a marker for systemic vascular disease, is a significant predictor of increased risk for cardiovascular morbidity and mortality in the general population. The relationship between microalbuminuria and cardiovascular disease is unknown. The aim of this study is to examine the association between microalbuminuria and coronary collateral vessel (CCV) development in nondiabetic and nonhypertensive patients with unstable coronary artery disease (USCAD). One hundred and six patients that had USCAD without hypertension and diabetes participated in the study. Microalbuminuria was assessed by radioimmunoassay in 24-h urine collections performed on the first day, and coronary angiography was performed 2-4 days after admissions. In total, 26 patients (mean age 56+/-14 years) had the criteria of the microalbuminuria group and 80 patients with normoalbuminuria (mean age 59+/-11 years), who had one or more diseased vessels with 80% or more stenosis, were included in the control group. The CCVs are graded according to the Rentrop scoring system and a Rentrop grade >or=1 was accepted as CCV development. CCV development was detected in eight (23%) of 26 patients in the microalbuminuria group and in 53 (74%) of 80 patients in the normoalbuminuria group. CCV development in the patients in the normoalbuminuria group was significantly different from that of the patients in the microalbuminuria group (r = -0.15, P = 0.006). In conclusion, these findings suggest that CCV development is poorer in the microalbuminuria group than the normoalbuminuria group. This study shows that in patients with USCAD, microalbuminuria, which is related to systemic vascular disease, affects CCV development negatively.

Atrial fibrillation and heart rate independently correlate to microalbuminuria in hypertensive patients

AIMS

To investigate the relationship between microalbuminuria (MAU) and atrial fibrillation (AF) and to further evaluate whether the heart rate dependency of MAU in patients without AF is maintained in patients with a history of AF.

METHODS AND RESULTS

The International Survey Evaluating Microalbuminuria Routinely by Cardiologists in patients with Hypertension (I-SEARCH) included 18,900 patients without and 1705 patients with a history of AF suffering from hypertension and other risk factors for cardiovascular disease in 26 countries worldwide from September 2005 to March 2006. Heart rate, blood pressure, urinary albumin excretion, and an estimated glomerular filtration rate were determined among other parameters. The prevalence of MAU was higher at higher heart rate in both patients with and without a history of AF. Prevalence of MAU was about 10% higher in patients with a history of AF (P < 0.001). Male gender, the presence of diabetes mellitus, a higher heart rate, and a higher diastolic blood pressure were independently associated with increased odds for MAU in patients without and with a history of AF.

CONCLUSION

The prevalence of MAU in hypertensive patients with cardiovascular risk factors is related to heart rate and significantly higher in patients with a history of AF.

Hypercholesterolaemia and risk of coronary heart disease in the elderly: impact of age: the Copenhagen City Heart Study

BACKGROUND

Population and interventional studies have shown that high plasma-cholesterol is a risk factor of coronary heart disease (CHD). However, in most of the studies elderly people were excluded.

AIM

This paper assesses whether the effect of total plasma-cholesterol on the risk of incident CHD decreases with age in a healthy population.

METHODS

Within the Copenhagen City Heart Study in 1981-1983, 4647 men and 5829 women, aged 40-93 years, underwent a cardiovascular health examination including measurement of plasma-cholesterol. The cohort was followed with respect to incident CHD until 1994, i.e. before statins were introduced in Denmark.

RESULTS

In people below 60 years of age plasma-cholesterol levels on 5-6; 6-8; and >8 mmol/L were associated with relative risks of CHD on 2.0 (95% confidence interval (CI) 1.2-3.2, P=0.004); 3.1 (CI 2.0-5.0, P<0.001); and 5.1 (CI 2.8-9.3, P<0.001), respectively (reference group: plasma-cholesterol <5 mmol/L). In people aged 60-70 years a plasma-cholesterol level on 5-6 mmol/L was not associated with increased risk, whereas plasma-cholesterol on 6-8 mmol/L and >8 mmol/L was associated with relative risks on 1.3 (CI 1.0-1.8, P=0.03), and 2.3 (CI 1.6-3.4, P<0.001), respectively. In people aged 70-80 years only plasma-cholesterol >8 mmol/L conferred increased relative risk on 1.6 (CI 1.2-2.4, P=0.007). In people above 80 years of age increased plasma-cholesterol was not associated with increased risk of incident CHD.

CONCLUSION

The risk of incident CHD associated with high plasma-cholesterol declines with age. This finding should be considered in future recommendations of plasma-cholesterol levels in elderly people without atherosclerotic cardiovascular disease.

Association of heart rate with microalbuminuria in cardiovascular risk patients: data from I-SEARCH

BACKGROUND

Microalbuminuria (MAU) is an indicator of impaired renal function and a relevant risk predictor for cardiovascular events. An increased heart rate is closely correlated with increased cardiovascular mortality. The International Survey Evaluating Microalbuminuria Routinely by Cardiologists in Patients with Hypertension (I-SEARCH) investigated 21 050 patients with hypertension and risk factors for cardiovascular disease. In patients in sinus rhythm (n = 18 900) the relationship between increased heart rate and the prevalence of MAU was analysed.

METHODS AND RESULTS

The study was performed in 26 countries worldwide from September 2005 to March 2006. Heart rate, blood pressure, urine albumin and serum creatinine were measured as key parameters. With increasing heart rate (> 80 bpm to < 120 bpm) the proportion of patients with MAU increased from 63 to 69% (P < 0.0001). The odds ratio (OR) for MAU increased with increasing heart rate [heart rate 80-100 bpm compared with 60 bpm: OR, 1.47; 95% confidence interval (CI), 1.29-1.68; P < 0.0001; and heart rate 100-120 bpm compared with 60 bpm: OR, 1.56; 95% CI, 1.22-1.99; P = 0.0004]. The prevalence of MAU was similar whether or not patients were receiving beta-blockers; but MAU was significantly reduced in physically active patients compared with sedentary patients (OR, 0.78; 95% CI, 0.73-0.84; P < 0.0001).

SUMMARY

These results show that heart rate is an independent predictor for the prevalence of MAU in hypertensive patients with cardiovascular risk factors. In contrast to beta-blocker therapy, physical activity markedly decreased MAU with increasing heart rates. Further controlled and prospective studies are needed to show that lowered heart rates in combination with MAU can significantly reduce kidney damage, as well as cardiovascular events.

Insulin resistance is the major determinant for microalbuminuria in severe hypertriglyceridemia: implication for high-risk stratification

OBJECTIVE

The significance of high triglyceride levels as a risk factor for coronary heart disease is uncertain. We hypothesized that oral glucose tolerance test (OGTT) and certain novel markers may help to identify high-risk patients.

PATIENTS AND METHODS

We recruited 80 subjects with severe hypertriglyceridemia (age 27-73 years) without clinical proteinuria and diabetes mellitus (DM) which were diagnosed by fasting glucose <126 mg/dL from Hyperlipidemia Clinic of National Taiwan University Hospital for this study. We applied OGTT to evaluate occult DM and homeostasis model assessment (HOMA)-insulin resistance (IR) score to evaluate insulin resistance, and the measurements of microalbuminuria as a marker of vascular damage. In addition, serum or plasma markers of inflammation and fibrinolysis, fasting glucose and insulin as well as traditional cardiovascular risk factors were also evaluated.

RESULTS

The serum level of triglyceride was higher in patients with microalbuminuria than in those without (14.1+/-5.7 vs. 9.6+/-3.9 mmol/L, p=0.025). Patients with microalbuminuria had higher fasting blood glucose and insulin, higher post-OGTT glucose and insulin, higher prevalence of newly developed diabetes mellitus (DM) (39% vs. 11%, p=0.007) and higher HOMA-IR (6.2+/-4.4 vs. 3.3+/-2.0, p<0.001). Among all the inflammatory and fibrinolytic markers, only soluble intercellular adhesion molecule showed significant different between these two groups. Multiple logistic regression analysis showed that among the serum markers, only HOMA-IR level was significantly related to microalbuminuria.

CONCLUSIONS

HOMA-IR is the major determinant for microalbuminuria in patients with severe hypertriglyceridemia. Impaired glucose metabolism is evident in patients with both severe hypertriglyceridemia and microalbuminuria.

Cardiovascular Implications of Albuminuria

Microalbuminuria is a major independent risk factor for cardiovascular disease (CVD) events in persons with diabetes or hypertension, the general population, and persons with known CVD. Although microalbuminuria is a stronger risk factor in men, women with increased albuminuria levels are also at a higher risk of CVD. Microalbuminuria is an indicator of generalized endothelial injury, a hallmark of systemic atherosclerosis. Treatments that decrease albuminuria, particularly agents that inhibit the renin-angiotensin system, reduce CVD risk in various populations, including those with and without diabetes or hypertension. Whether albuminuria should be a treatment target for CVD is not yet proven. Nevertheless, the measurement of albuminuria is clinically useful to identify high-risk individuals who should receive intensive risk factor management based on current treatment guidelines.

Low-grade albuminuria and cardiovascular risk : what is the evidence?

Microalbuminuria (MA), conventionally defined as a urinary albumin excretion (UAE) of 30-300 mg/day, is recognised as a marker of endothelial dysfunction. Furthermore, it represents an established risk factor for cardiovascular morbidity and mortality and for end-stage renal disease in individuals with an adverse cardiovascular risk profile. It is common in the general population, particularly in patients with diabetes mellitus or arterial hypertension. There is growing evidence from prospective observational trials that UAE levels well below the current MA threshold ("lowgrade MA") are also associated with an increased risk of incident cardiovascular disease and allcause mortality. Even in apparently healthy individuals (without diabetes or hypertension), such an association has been shown. As albuminuria screening assays that are reliable even in the lower ranges are commercially available, there may be an important clinical role for MA in disease screening, comparable to the role of blood pressure and lipid screening. MA is modifiable, and the inhibition of the renin-angiotensin system by ACE inhibitors and AT1 receptor antagonists has been shown to result in a lower incidence of cardiovascular events.

Relationship between metabolic syndrome components and vascular properties in Japanese type 2 diabetic patients without cardiovascular disease or nephropathy

To investigate the effect of metabolic syndrome (MS) components on early atherosclerosis markers, i.e., urinary albumin excretion rate (UAE), pulse wave velocity (PWV), and carotid intima-media thickness (IMT), we studied 536 Japanese patients with type 2 diabetes without cardiovascular disease or nephropathy. The MS definition by ATP III was employed. UAE, PWV, and IMT increased significantly with increasing the number of components even before fulfilling the diagnosis of MS. UAE was significantly influenced by high blood pressure, high triglycerides, and low HDL cholesterol. PWV was significantly increased by high blood pressure. IMT was significantly increased by high blood pressure and abdominal obesity. Multiple regression analysis, including MS components and putative risk factors, indicated that the number of MS components, age and glycosylated HbA1C were independent determinants of UAE, PWV, and IMT. LDL cholesterol and male gender were independent determinants of IMT. In conclusion, UAE, PWV, and IMT increased according to increasing the number of MS in type 2 diabetic patients without cardiovascular disease or diabetic nephropathy. The current observation considering the modifiable factors may help to identify patients who are at high risk of experiencing cardiovascular disease.

Urinary albumin excretion and the renin-angiotensin system in cardiovascular risk management

Microalbuminuria has been shown to be a strong predictor of cardiovascular morbidity and mortality in diabetic and hypertensive patients, but also in the general population. Moreover, several reports suggest that reduction of urinary albumin excretion (UAE) is associated with improvement of cardiovascular prognosis. Reduction of UAE can be achieved by lowering arterial blood pressure, but blockers of the renin-angiotensin system (RAS) with their specific renal actions have demonstrated to be able to reduce UAE more than might be expected from reduction of blood pressure alone. Consequently, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may also provide superior cardiovascular protection, especially in subjects with higher levels of albuminuria, but evidence is still scarce. The ability of both angiotensin-converting enzyme inhibitors and angiotensin receptor blockers to reduce UAE and provide cardiovascular protection suggests that the RAS may play a central role. New developments in this area include the use of aldosterone antagonists in albuminuric/proteinuric subjects, and the development of oral renin inhibitors. Combinations of the aforementioned drugs may have the ability to fully block the RAS, potentially avoiding all detrimental effects of this hormonal cascade. However, combination therapy is expected to also increase the incidence of side effects, such as hyperkalaemia and acute renal insufficiency. The current knowledge of microalbuminuria represents the proverbial tip of the iceberg, and future studies should focus on the underlying pathophysiological mechanism of urinary albumin excretion in relation to cardiovascular protection. Only then can a better understanding of the problem be achieved and the optimal pharmacological approach be ascertained.

Microalbuminuria

Microalbuminuria, originally described more than 3 decades ago as a predictor of nephropathy in patients who had type 1 diabetes mellitus and associated with higher cardiovascular risk, is now linked with increased risk for cardiovascular events rather than progression to end-stage kidney disease. This article reviews the role of microalbuminuria in the context of atherosclerotic vascular disease. It presents the methods for microalbuminuria assessment in clinical practice, its relations with other cardiovascular risk factors, and the pathophysiologic associations between microalbuminuria and vascular damage. In addition, this article discusses the prognostic significance of microalbuminuria for cardiovascular disease as well as existing therapeutic interventions for reducing urine albumin excretion in patients who are at high cardiovascular risk.

Very low level of microalbuminuria is associated with increased risk of death in subjects with cardiovascular or cerebrovascular diseases

BACKGROUND

The original definition of microalbuminuria (20-200 microg min-1 or 15-150 microg min-1 overnight) is based on studies of patients with diabetes, in whom microalbuminuria was associated with increased risk of chronic renal failure. In a recent report an overnight urinary albumin excretion (UAE) above only 5 microg min-1 was strongly predictive of coronary heart disease and death in the general population. The aim of the present study was to investigate if this cut-off level also has prognostic value in a population with cardiovascular or cerebrovascular disease.

METHODS AND RESULTS

In The Third Copenhagen City Heart Study in 1992-1994, 491 men and women aged 30-80 years with a history of coronary heart disease or stroke delivered a timed overnight urine sample. They were followed by registers with respect to vital status until 2004. During follow-up, 141 of the 491 participants died. The relative risk of death in subjects with UAE above 5 microg min-1 compared with subjects with lower UAE was 2.0 (1.4-2.8; P<0.001). It was unaffected [RR 1.9 (1.3-2.7); P<0.005] by adjustment for age, sex, blood pressure, diabetes, lipoproteins, renal creatinine clearance, smoking and body mass index.

CONCLUSIONS

Subjects with cardiovascular or cerebrovascular disease have about 100% higher risk of death if microalbuminuria defined as UAE above 5 microg min-1 is present. Measurements of UAE should be included in the risk assessment in subjects with cardiovascular or cerebrovascular disease. This study supports the definition of microalbuminuria as UAE above 5 microg min-1.

Microalbuminuria is determined by systolic and pulse pressure over a 12-year period and related to peripheral artery disease in normotensive and hypertensive subjects: the Three Areas Study in Greece (TAS-GR)

Microalbuminuria and peripheral artery disease represent 2 different forms of target organ damage due to raised blood pressure. The aim of this study was to investigate the association between blood pressure with microalbuminuria and the appearance of peripheral artery disease after more than a decade, and moreover, to address whether any relationship exists between microalbuminuria and peripheral disease in a Greek Caucasian population. In 1990, 635 normal subjects were examined and their blood pressure was recorded. Nine and 12 years later, subjects were reexamined and 361 of them (57%) were available at last visit for the determination of microalbuminuria and ankle-arm index. Microalbuminuria was detected in 35/361 (9.7%) and peripheral artery disease in 89/361 (24.7%). Both conditions were statistically correlated with pulse and systolic blood pressure at all time points during the 12-year follow-up period, while the relationship with diastolic and mean arterial pressure existed only for baseline values and was then abolished. Microalbuminuria was statistically correlated to peripheral artery disease (r = -0.460, p = 0.0001). Blood pressure levels seemed to predict the appearance of microalbuminuria and peripheral disease after 12 years. Microvasculature and macrovasculature abnormalities (microalbuminuria and peripheral disease, respectively) showed a significant relationship, suggesting a common pathogenetic mechanism.

Reductions in albuminuria and in electrocardiographic left ventricular hypertrophy independently improve prognosis in hypertension: the LIFE study

BACKGROUND

In the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study, reduced urine albumin/creatinine ratio (UACR) as well as regression of left ventricular hypertrophy have been associated with lower incidence of cardiovascular events. We wanted to investigate whether these prognostic improvements were independent.

METHODS

In 6679 hypertensive patients included in the LIFE study, we measured UACR, left ventricular hypertrophy by electrocardiography, serum cholesterol, plasma glucose and blood pressure after 2 weeks of placebo treatment and again after 1 year of anti-hypertensive treatment with either an atenolol- or a losartan-based regimen. During this first year of treatment, 77 patients encountered a non-fatal stroke or myocardial infarction and were excluded to avoid bias. During the next 3-4 years, 610 composite endpoints [cardiovascular death (n = 228), fatal or non-fatal myocardial infarction or stroke] were recorded.

RESULTS

In Cox regression analyses, the composite endpoint was after adjustment for treatment allocation predicted by baseline logUACR [hazard ratio (HR) = 1.16 per 10-fold increase, P < 0.05], 1-year logUACR (HR = 1.29 per 10-fold increase), baseline Sokolow-Lyon voltage (HR = 1.01 per mm, both P < 0.001) and 1-year Cornell product (HR = 1.01 per 100 mm x ms, P < 0.01). Cardiovascular death was predicted by 1-year logUACR (HR = 1.59, P < 0.001), baseline Sokolow-Lyon voltage (HR = 1.01, P = 0.06) and 1-year Cornell product (HR = 1.02, P < 0.001). Both were predicted independent of age, Framingham risk score, current smoking, history of cardiovascular disease and diabetes. Gender, serum cholesterol, plasma glucose and blood pressure did not enter the models.

CONCLUSIONS

Baseline UACR and Sokolow-Lyon voltage, as well as in-treatment UACR and Cornell product, added to the risk prediction independent of traditional risk factors, indicating that albuminuria and left ventricular hypertrophy reflect different aspects of cardiovascular damage and are modifiable cardiovascular risk factors.

Albuminuria and incident coronary heart disease in Australian Aboriginal people

BACKGROUND

It has been suggested that albuminuria is useful in identifying persons at increased risk of coronary heart disease (CHD). Australian Aborigines have exceedingly high rates of renal failure together with increased CHD mortality. We undertook this prospective cohort study to assess the independent effect of albuminuria on CHD risk in Aboriginal people in the Northern Territory of Australia.

METHODS

We examined the relation between micro- and macroalbuminuria and incident CHD in a sample of 870 Aboriginal adults aged 20 to 74 years old without prevalent baseline CHD. Cox proportional hazards models were used to assess the association between baseline albuminuria and CHD incidence.

RESULTS

During a median of 9.2 years of follow-up, 89 CHD events occurred during the follow-up period (1992 to 2003). The incidence of CHD increased significantly across categories of albuminuria (4.4, 10.9, and 29.8 per 1000 person-years for normoalbuminuria, microalbuminuria, and macroalbuminuria, respectively). The multiple Cox proportional hazards regression showed the hazard ratio was 3.4 (95% CI 1.6, 7.3), adjusting for age, gender, body mass index (BMI), blood pressure, total cholesterol, diabetes status, cigarette smoking, and alcohol consumption, for macroalbuminuria group. Hazard ratio for microalbuminuria group was not significantly different from unity during the first 6 years of follow-up but significantly higher during the follow-up period > or = 6 years with adjusted hazard ratio 9.0 (95% CI 2.0, 40.0).

CONCLUSION

Independent of traditional cardiovascular risk factors, both microalbuminuria and macroalbuminuria may be useful in identifying persons at increased risk of CHD in Aboriginal people.

Impact of statins in microalbuminuric subjects with the metabolic syndrome: a substudy of the PREVEND Intervention Trial

AIMS

Microalbuminuria frequently clusters with the metabolic syndrome and may identify subjects at increased coronary risk. Statin treatment may reduce the incidence of major adverse cardiac events in subjects with the metabolic syndrome, but evidence is limited. We evaluated the impact of pravastatin treatment on the incidence of major adverse cardiac events in microalbuminuric subjects with the metabolic syndrome.

METHODS AND RESULTS

This substudy of the PREVEND Intervention Trial (a randomized, placebo-controlled trial with a 2x2 factorial design) included 864 microalbuminuric subjects, who were randomized to fosinopril 20 mg or matching placebo and pravastatin 40 mg or matching placebo (mean follow-up 46 months). The metabolic syndrome was defined according to the NCEP ATPIII-report. Subjects with or without the metabolic syndrome were characterized by a higher age, male sex, and increased albuminuria. The incidence of major adverse cardiac events in subjects with the metabolic syndrome [9.1%; 95% confidence interval (CI) 6.0-13.0%] was increased vs. those without [3.6%; 95% CI 2.3-5.5%; P=0.007). Pravastatin treatment lowered the incidence of major adverse cardiac events in subjects with the metabolic syndrome after adjustment for age and sex (hazard ratio=0.39; 95% CI 0.17-0.89; P=0.025).

CONCLUSION

This study supports the use of statins in microalbuminuric subjects with the metabolic syndrome to reduce the incidence of major adverse cardiac events.

Uric acid, microalbuminuria and cardiovascular events in high-risk patients

BACKGROUND

Elevated levels of serum uric acid and albuminuria are associated with cardiovascular disease, but the relationships have not consistently been demonstrated to be independent of hypertension, other risk factors, or each other. The purpose of this study was to evaluate people at high risk for cardiovascular disease for the influence of uric acid and microalbuminuria on cardiovascular events.

METHODS

Consecutive consenting patients undergoing elective angiography (n = 316) had coronary artery disease, risk factors, renal function and diuretic use assessed at baseline. Cardiovascular mortality and major clinical events (myocardial infarction, stroke, amputation, and kidney failure) were ascertained over 5 years.

RESULTS

Cardiovascular events occurred in 10% of the patients. Significant correlates (p < 0.05) of cardiovascular events with baseline measures included uric acid > or =5.2 mg/dl, total cholesterol > or =200 mg/dl, severe angiographic coronary artery disease, loop diuretic therapy, and diagnosis of hypertension. A stepwise Cox modeling procedure identified uric acid (p = 0.040), the interaction of hypertension and uric acid (p = 0.029), the interaction of total cholesterol and severe coronary artery disease (p = 0.001) and loop diuretic therapy (p = 0.009) as significant independent predictors of events. Although microalbuminuria was not retained in the final multivariate model, it was associated with poorer cardiovascular disease outcomes. The mean event-free survival for albumin-to-creatinine >30 mg/g was 51 months and for albumin-to-creatinine <30 mg/g the mean was 57 months (p = 0.021).

CONCLUSIONS

Uric acid > or =5.2 mg/dl independently imparted a 3.5-fold increased risk (OR 3.5, 95% CI 1.0-11.9) for cardiovascular death and major clinical events over a 5-year period. Uric acid may be a contributing factor to the progression of atherosclerosis and its complications.

Effect of proteinuria and glomerular filtration rate on cardiovascular risk in essential hypertension

Changes in renal function related with essential hypertension are associated with an elevated cardiovascular morbidity and mortality. Indices of altered renal function (e.g., microalbuminuria, increased serum creatinine concentrations, decrease in estimated creatinine clearance or GFR, and overt proteinuria) are independent predictors of cardiovascular morbidity and mortality. The Framingham Heart Study documented the relevance of proteinuria for cardiovascular prognosis in the community. The INSIGHT Study assessed the role of proteinuria as a risk factor in essential hypertension. The presence of proteinuria at baseline turned out to be a very potent predictor for the development of cardiovascular events and death in patients with essential hypertension and one or more associated cardiovascular risk factors. Recent data indicate that minor derangements of renal function, including proteinuria, are associated, both in the community and in the hypertensive population, with the clustering of cardiovascular risk factors observed in metabolic syndrome that promote progression of atherosclerosis. Renal function has to be routinely evaluated in every hypertensive patient, and the presence of minor alterations considered in the stratification of cardiovascular risk in hypertensive patients.

The association of silent coronary artery disease and metabolic syndrome in Chinese with type 2 diabetes mellitus

OBJECTIVES

Cardiovascular diseases account for approximately 75% of the deaths that occur in patients with diabetes. Because the clinical signs of coronary artery disease (CAD) in diabetic patients are hard to detect and routine screening is costly, it would be of great benefit to try to either prevent CAD from occurring or to detect it early and provide optimal care. Therefore, we analyzed the risk factors that might predict CAD in type 2 diabetes mellitus (T2DM) patients with no classical cardiac ischemic symptoms.

METHODS

Using a resting 12-lead ECG, exercise treadmill test, or thallium myocardial scintigraphy with exercise testing and dipyridamole injection, we screened diabetic patients already enrolled in a disease management program for possible CAD. We used diagnostic coronary angiography to confirm its presence. The definition and criteria of metabolic syndrome we used were modified from those outlined by the WHO classification and criteria of NCEP-ATP III.

RESULTS

A total of 850 T2DM patients without clinical and electrocardiographic evidence of CAD were studied. Three hundred and sixty-eight asymptomatic patients with normal resting ECG were examined by exercise ECG test or thallium scintigraphy examination. Sixty patients considered to have a strong positive test or significant thallium myocardial ischemia received a diagnostic coronary angiography. Fifty-one were found to have significant coronary artery stenosis; 9 showed no significant ischemic lesion. While gender, patients' age, known diabetes duration, serum uric acid level, smoking status, and the presence of WHO-metabolic syndrome defined hypertension and nephropathy were associated with silent CAD, logistic regression analysis found that the only predictor of silent CAD was the presence of nephropathy. The components of NCEP-ATP III-metabolic syndrome were not found to be associated with silent CAD.

CONCLUSIONS

A considerable proportion of T2DM patients have silent CAD. A diabetic patient with incipient or overt nephropathy should be examined for the presence of CAD. The definition of metabolic syndrome may be modified for early detection of CAD in patients with T2DM.

Albuminuria predicts cardiovascular events independently of left ventricular mass in hypertension: a LIFE substudy

We wanted to investigate whether urine albumin/creatinine ratio (UACR) and left ventricular (LV) mass, both being associated with diabetes and increased blood pressure, predicted cardiovascular events in patients with hypertension independently. After 2 weeks of placebo treatment, clinical, laboratory and echocardiographic variables were assessed in 960 hypertensive patients from the LIFE Echo substudy with electrocardiographic LV hypertrophy. Morning urine albumin and creatinine were measured to calculate UACR. The patients were followed for 60+/-4 months and the composite end point (CEP) of cardiovascular (CV) death, nonfatal stroke or nonfatal myocardial infarction was recorded. The incidence of CEP increased with increasing LV mass (below the lower quartile of 194 g to above the upper quartile of 263 g) in patients with UACR below (6.7, 5.0, 9.1%) and above the median value of 1.406 mg/mmol (9.7, 17.0, 19.0%(***)). Also the incidence of CV death increased with LV mass in patients with UACR below (0, 1.4, 1.3%) and above 1.406 mg/mmol (2.2, 6.4, 8.0%(**)). The incidence of CEP was predicted by logUACR (hazard ratio (HR)=1.44(**) for every 10-fold increase in UACR) after adjustment for Framingham risk score (HR=1.05(***)), history of peripheral vascular disease (HR=2.3(*)) and cerebrovascular disease (HR=2.1(*)). LV mass did not enter the model. LogUACR predicted CV death (HR=2.4(**)) independently of LV mass (HR=1.01(*) per gram) after adjustment for Framingham risk score (HR=1.05(*)), history of diabetes mellitus (HR=2.4(*)) and cerebrovascular disease (HR=3.2(*)). (*)P<0.05, (**)P<0.01, (***)P<0.001. In conclusion, UACR predicted CEP and CV death independently of LV mass. CV death was predicted by UACR and LV mass in an additive manner after adjustment for Framingham risk score and history of CV disease.

Microalbuminuria as a marker of cardiovascular and renal risk in type 2 diabetes mellitus: a temporal perspective

Microalbuminuria is a marker for diabetic nephropathy. It also signifies cardiovascular disease, as well as nephropathy, in type 2 diabetes (DM2). Microalbuminuria may precede DM2, occurring with the insulin resistance syndrome and its components, including obesity and hypertension. Other indicators of cardiovascular risk, such as markers of inflammation, are associated with microalbuminuria in populations of patients with and without diabetes. With the rising prevalence of DM2 in minority youth, especially in Native Americans, a marker for future disease risk would allow earlier prevention strategies to be tested. Before microalbuminuria can be used in a prevention strategy, more needs to be known about the mechanism(s) of the association between elevated excretion, its relationship to glucose intolerance, and its relative contribution to cardiovascular and renal disease. These questions are especially applicable as we begin to observe the long-term complications of diabetes in youth.

Effect of antidiabetic medications on microalbuminuria in patients with type 2 diabetes

The progression of diabetes and hypertension complications is associated with microalbuminuria. Intensive glycemic control prevents or retards microalbuminuria in patients with type 2 diabetes, but little is known about the respective benefits of different antidiabetic drugs. We studied the effect of gliclazide and pioglitazone on microalbuminuria in patients with type 2 diabetes. We excluded patients with very poor glycemic control (glycated hemoglobin [HbA(1c)] >10%), impaired liver function, nondiabetic renal diseases, and those whose urine contained red blood cells, hemoglobin, or casts. Each patient received the designated drug for 12 weeks and their body weight, blood pressure (BP), fasting plasma glucose (FPG), HbA(1c), lipids (triglycerides [TG], total, and high-density lipoprotein-cholesterol [HDL-C]), 1,5 anhidroglucitol (1,5-AG), immunoreactive insulin (IRI), and urinary albumin to creatinine ratio (UACR) were measured every month. The effects of the drugs were analyzed using 2-way repeated measures analysis of variance (ANOVA). The 2 groups of patients were well matched for age, duration of diabetes, retinal status, blood pressure, body mass index (BMI), IRI, FPG, HBA(1c), 1,5-AG, lipids, and UACR, as well as the use of antihypertensive drugs. After treatment, no significant differences were seen in drug efficacy between the 2 groups. Gliclazide and pioglitazone significantly reduced FPG (F = 26.0, P <.0001), HBA(1c) (F = 48.1, P <.0001), and total cholesterol (TC) levels (F = 3.5, P <.05). Decrements in these metabolic parameters were comparable between the groups. 1,5-AG increased in both groups (F = 27.5, P <.0001), and the increment was comparable in both groups. Gliclazide and pioglitazone significantly reduced UACR (F = 15.7, P <.0001) with a comparable decrement in both groups. No other variables changed significantly throughout the 12-week treatment. These results suggest that 12 weeks of treatment with gliclazide or pioglitazone are equally effective in reducing microalbuminuria with similar improvements in blood glucose and cholesterol levels, independent of their mechanisms of actions.

Microalbuminuria and stroke in a British population: the European Prospective Investigation into Cancer in Norfolk (EPIC-Norfolk) population study

OBJECTIVES

To examine the relationship between microalbuminuria and incident stroke in the general population.

DESIGN

Population-based prospective cohort study.

SETTING

Participants were recruited in a primary care setting from 35 participating general practice units in Norfolk, UK.

SUBJECTS AND MAIN OUTCOME MEASURES

The study population consisted of 23,630 individuals aged 40-79 years recruited between 1993 and 1997 for the EPIC-Norfolk Study and followed up for an average of 7.2 years. Random spot urine specimens were collected at baseline and albumin-to-creatinine ratio measured. Participants were categorized into normoalbuminuria, microalbuminuria and macroalbuminuria groups. During follow-up, the main end point was stroke incidence (fatal and nonfatal), ascertained from the UK Office for National Statistics and from the National Health Service Health District database of all hospital admissions.

RESULTS

A total of 246 stroke events occurred during follow-up [crude incidence rate of stroke, 1.5 per 1000 person years (pyrs)]. The age-adjusted incidence of stroke increased significantly across categories of baseline albuminuria (0.9, 1.1 and 1.4/1000 pyrs for tertiles of normoalbuminuria, 2.6/1000 pyrs for microalbuminuria, and 6/1000 pyrs for macroalbuminuria in the total population, P < 0.001 for trend). In all women and men, the multivariate hazard ratio [95% confidence interval (CI)] for stroke associated with microalbuminuria was 1.49 (1.13-2.14) and macroalbuminuria 2.43 (1.11-6.26). After stratifying by stroke subtype, microalbuminuria was only independently predictive of ischaemic stroke, with hazard ratio (95% CI) of 2.01 (1.29-3.31).

CONCLUSION

Microalbuminuria is independently associated with approximately 50% increased risk of stroke in the general population. Microalbuminuria may be useful in identifying those at increased risk of stroke in the general population.

Is it time to measure microalbuminuria in hypertension?

Former guidelines on hypertension never made a commitment to the detection of microalbuminuria for screening or follow-up of hypertensive patients. On the other hand, growing evidence support the contributory role of microalbuminuria in the prediction of absolute cardiovascular risk in hypertension and document the potential relevance of this parameter to the initial choice of antihypertensive treatment. Upcoming new guidelines and diagnostic algorithms in hypertension need to underscore the clinical positioning of microalbuminuria for stratification of risk and follow-up purposes.

Microalbuminuria in hypertensive patients with electrocardiographic left ventricular hypertrophy: the LIFE study

OBJECTIVES

Left ventricular hypertrophy and albuminuria have both been shown to predict increased cardiovascular morbidity and mortality. However, the relationship between these markers of cardiac and renal glomerular damage has not been evaluated in a large hypertensive population with target organ damage. The present study was undertaken to determine whether albuminuria is associated with persistent electrocardiographic (ECG) left ventricular hypertrophy, independent of established risk factors for cardiac hypertrophy, in a large hypertensive population with left ventricular hypertrophy who were free of overt renal failure.

METHODS

Patients with stage II-III hypertension were enrolled in the study if they had left ventricular hypertrophy on a screening ECG by Cornell voltage-duration product and/or Sokolow-Lyon voltage criteria, and clinic blood pressures between 160 and 200/95-115 mmHg and plasma creatinine < 160 mmol/l. A second ECG and morning spot urine were obtained after 14 days of placebo treatment. Renal glomerular permeability was evaluated by urine albumin/creatinine (UACR, mg/mmol). Microalbuminuria was present if UACR > 3.5 mg/mmol and macroalbuminuria if UACR > 35 mg/mmol.

RESULTS

The mean age of the 8029 patients was 66 years, 54% were women. Microalbuminuria was found in 23% and macroalbuminuria in 4% of patients. Microalbuminuria was more prevalent in patients of African American (35%), Hispanic (37%) and Asian (36%) ethnicity, heavy smokers (32%), diabetics (36%) and in patients with ECG left ventricular hypertrophy by both ECG-criteria (29%). Urine albumin/creatinine was positively related to Sokolow-Lyon voltage criteria and Cornell voltage-duration product criteria. In multiple regression analysis, higher UACR was independently associated with older age, diabetes, higher blood pressure, serum creatinine, smoking and left ventricular hypertrophy. Patients smoking > 20 cigarettes/day had a 1.6-fold higher prevalence of microalbuminuria and a 3.7-fold higher prevalence of macroalbuminuria than never-smokers. ECG left ventricular hypertrophy by Cornell voltage-duration product or Sokolow-Lyon criteria was associated with a 1.6-fold increased prevalence of microalbuminuria and a 2.6-fold increase risk of macroalbuminuria compared to no left ventricular hypertrophy on the second ECG.

CONCLUSIONS

In patients with moderately severe hypertension, left ventricular hypertrophy on two consecutive ECGs is associated with increased prevalences of micro- and macroalbuminuria compared to patients without persistent ECG left ventricular hypertrophy. High albumin excretion was related to left ventricular hypertrophy independent of age, blood pressure, diabetes, race, serum creatinine or smoking, suggesting parallel cardiac damage and albuminuria.

Urine albumin/creatinine ratio and echocardiographic left ventricular structure and function in hypertensive patients with electrocardiographic left ventricular hypertrophy: the LIFE study. Losartan Intervention for Endpoint Reduction

BACKGROUND

Albuminuria, reflecting systemic microvascular damage, and left ventricular (LV) geometric abnormalities have both been shown to predict increased cardiovascular morbidity and mortality. However, the relationship between these markers of cardiovascular damage has not been evaluated in a large hypertensive population.

METHODS

The urine albumin/creatinine ratio (UACR) and echocardiographic measures of LV structure and function were obtained in 833 patients with stage I to III hypertension and LV hypertrophy determined by electrocardiogram (ECG) (Cornell voltage-duration or Sokolow-Lyon voltage criteria) after 14 days of placebo treatment.

RESULTS

Patients' mean ages were 66 years, 42% were women, 23% had microalbuminuria, and 5% had macroalbuminuria. Patients with eccentric or concentric LV hypertrophy had higher prevalences of microalbuminuria (average 26%-30% vs 9%, P <.001) and macroalbuminuria (6%-7% vs <1%, P <.001). Furthermore, patients with microalbuminuria and macroalbuminuria had a significantly higher LV mass and lower endocardial and midwall fractional shortening. Patients with abnormal diastolic LV filling parameters had a significantly increased prevalence of microalbuminuria. In univariate analyses, UACR correlated positively to LV mass, systolic blood pressure, age (all P <.001) and pulse pressure/stroke volume and negatively to relative wall thickness (both P <.01) and endocardial (P <.05) and midwall shortening (P <.001) but not to diastolic filling parameters. In multiple regression analysis higher UACR was associated with higher LV mass (beta=.169, P <.001) independently of older age (beta =.095, P <.01), higher systolic pressure (beta=.163), black race (beta=.186), and diabetes (beta=.241, all P <.001).

CONCLUSIONS

In hypertensive patients with ECG LV hypertrophy, abnormal LV geometry and high LV mass are associated with high UACR independent of age, systolic blood pressure, diabetes, and race, suggesting parallel cardiac and microvascular damage.

Microalbuminuria: marker of vascular dysfunction, risk factor for cardiovascular disease

Based on the data from large single and multi-center clinical trials, including the Heart Outcomes Prevention Evaluation (HOPE) study, it is clear that the presence of microalbuminuria is a signal from the kidney that cardiovascular risk is increased and that vascular responses are altered. This is exemplified by studies that have demonstrated that the compensatory vasodilation seen following relief from prolonged ischemia or infusion of vasodilators such as nitroglycerin is blunted in people with microalbuminuria. Thus, the presence of between 30 and 299 mg/day of albumin in the urine is associated with abnormal vascular responsiveness, which may be the result of more advanced atherosclerosis and not necessarily related to the presence of hypertension or renal disease. Agents known to reduce the rise in microalbuminuria or actually reduce the level of microalbuminuria, such as ACE inhibitors, angiotensin receptor blockers, HMG-CoA reductase inhibitors, beta blockers, non-dihydropyridine calcium channel blockers and diuretics, have all been shown to reduce cardiovascular mortality and in some cases preserve renal function. This article will present an overview of the data that support the assertion that a reduction in the rise of microalbuminuria is a significant consideration in the selection of agents to treat a given risk factor (cholesterol or blood pressure) to a recommended target goal. Achieving such a goal with agents that also impact microalbuminuria will provide for a more complete cardiovascular risk reduction.

Non-diabetic microalbuminuria, endothelial dysfunction and cardiovascular disease

Subclinical increases in albuminuria (microalbuminuria) predict morbid events, but the reasons for that are still not understood in full. This paper reviews the existing evidence regarding the relationships of non-diabetic microalbuminuria and cardiovascular disease, the underlying assumption being that endothelial dysfunction contributes both to atherosclerotic macrovascular disease and renal microvascular disease of which albuminuria is a marker. Much data support that concept, and suggest a preferential link with endothelial activation in response to acute and subclinical inflammatory stimulation, although further studies are needed to establish the exact cause-effect mechanisms. Epidemiological studies also show associations with cardiovascular events, and some recent prospective results also indicate the power of microalbuminuria to predict risk independently from conventional atherogenic factors. Thus, microalbuminuria might be considered as an integrated marker of cardiovascular risk sensitive to systemic vascular status in addition to other parameters such as blood pressure levels, glucose metabolism, smoking habits, a profile rather unique among the prognostic predictors available to stratify risk in hypertensive patients.

Microalbuminuria in essential hypertension: significance, pathophysiology, and therapeutic implications

Some patients with essential hypertension manifest greater than normal urinary albumin excretion (UAE). The significance of this association, which is the object of this review, is not well established. Hypertensive patients with microalbuminuria manifest greater levels of blood pressure, particularly at night, and higher serum levels of cholesterol, triglycerides, and uric acid than patients with normal UAE. Levels of high-density lipoprotein cholesterol, on the other hand, were lower in patients with microalbuminuria than in those with normal UAE. Patients with microalbuminuria manifested greater incidence of insulin resistance and thicker carotid arteries than patients with normal UAE. After a follow-up of 7 years, we observed that 12 cardiovascular events occurred among 54 (21.3%) patients with microalbuminuria and only two such events among 87 patients with normal UAE (P < 0.0002). Stepwise logistic regression analysis showed that UAE, cholesterol level, and diastolic blood pressure were independent predictors of the cardiovascular outcome. Rate of creatinine clearance from patients with microalbuminuria decreased more than that from those with normal UAE. In conclusion, these studies suggest that hypertensive individuals with microalbuminuria manifest a variety of biochemical and hormonal derangements with pathogenic potential, which results in hypertensive patients having a greater incidence of cardiovascular events and a greater decline in renal function than patients with normal UAE.

Urinary albumin and insulin as predictors of coronary artery disease: An angiographic study

Microalbuminuria has been associated with cardiovascular risk factors, events, and mortality. It also clusters with hyperinsulinemia and the metabolic syndrome. How urinary albumin excretion and the fasting serum insulin level relate to coronary artery disease (CAD) has not been previously determined. In 308 patients undergoing elective coronary angiography, the albumin to creatinine ratio was measured in urine from an early morning void. The fasting serum insulin level was also determined. CAD was assessed by angiography. Urinary albumin excretion was 28 +/- 5 mg/g (mean +/- SE) in patients with CAD and 10 +/- 1 mg/g in those without CAD (P < 0.001). Fasting serum insulin levels were also greater in patients with CAD compared with those without CAD; 20 +/- 3 and 13 +/- 1 microU/mL, respectively (P = 0.016). Urinary albumin excretion and fasting serum insulin levels increased progressively with severity of CAD. In patients without diabetes (n = 255), significant relationships of urinary albumin excretion and the fasting serum insulin levels to CAD were observed, but they were more pronounced when patients with diabetes (n = 53) were included. In multiple regression analysis, the odds ratios for severe CAD were 2.2 (95% confidence interval, 1.1 to 4.5) for microalbuminuria and 2. 2 (95% confidence interval, 1.3 to 3.8) for hyperinsulinemia. In summary, urinary albumin excretion and the fasting serum insulin levels were directly related to angiographic evidence of CAD. Microalbuminuria and hyperinsulinemia predict a significantly elevated risk for coronary atherosclerosis.

Microalbuminuria in essential hypertension

Microalbuminuria is frequently seen in patients with established essential hypertension, and is a predictor of a higher risk for cardiovascular and probably renal dysfunction. The presence of microalbuminuria has been shown to correlate with the other cardiovascular risk factors commonly seen in hypertensive patients. This fact indicates that the detection of an increased urinary albumin excretion could probably be the best index of an increased global cardiovascular risk in a given patient. Blood pressure control is accompanied by a fall in the content of albumin in urine. Agents with the capacity to block the renin-angiotensin system have shown a capacity to decrease urinary albumin excretion, which is independent of their ability to lower blood pressure. Whether or not a decrease in urinary albumin excretion is accompanied by an improved renal and cardiovascular prognosis in hypertensive patients remains to be elucidated.