Renal Congestion in Heart Failure: Insights in Novel Diagnostic Modalities

Heart failure is increasingly prevalent and is estimated to increase its burden in the following years. A well-reported comorbidity of heart failure is renal dysfunction, where predominantly changes in the patient's volume status, tubular necrosis or other mechanical and neurohormonal mechanisms seem to drive this impairment. Currently, there are established biomarkers evaluating the patient's clinical status solely regarding the cardiovascular or renal system. However, as the coexistence of heart and renal failure is common and related to increased mortality and hospitalization for heart failure, it is of major importance to establish novel diagnostic techniques, which could identify patients with or at risk for cardiorenal syndrome and assist in selecting the appropriate management for these patients. Such techniques include biomarkers and imaging. In regards to biomarkers, several peptides and miRNAs indicative of renal or tubular dysfunction seem to properly identify patients with cardiorenal syndrome early on in the course of the disease, while changes in their serum levels can also be helpful in identifying response to diuretic treatment. Current and novel imaging techniques can also identify heart failure patients with early renal insufficiency and assess the volume status and the effect of treatment of each patient. Furthermore, by assessing the renal morphology, these techniques could also help identify those at risk of kidney impairment. This review aims to present all relevant clinical and trial data available in order to provide an up-to-date summary of the modalities available to properly assess cardiorenal syndrome.

Low Level Of Neutrophil Gelatinase-Associated Lipocalin (NGAL) In Patients With Chronic Heart Failure And Multivessel Coronary Atherosclerosis

Rationale — Several biomarkers are used to determine the prognosis of patients with heart failure (HF), including neutrophil gelatinase-associated lipocalin (NGAL, Lipocalin-2). We investigated NGAL serum levels in patients with HF and coronary artery disease (CAD). Methods — Fifty-three patients with chronic HF and stable multivessel CAD were included in the study. Patients were grouped on the basis of the NGAL level: low NGAL group (NGAL<37 ng/mL, n=19) and normal NGAL group (NGAL ≥37 ng/mL, n=34). Results and Discussion — The main findings from our study of patients with HF and multivessel CAD were: 1) Plasma NGAL levels were below reference values in 35.8% of cases. 2) We detected a strong positive correlation between neutrophil count and NGAL level (0.573, р<0.001). 3) Neutropenia was present in 15.8% of patients in the low NGAL group and in none in the group with a normal NGAL level (p=0.041). 4) Postinfarction left ventricular aneurysms were more often diagnosed in patients of the first group (15.8%) and in none of patients in the second group (p=0.041). Conclusion — Low NGAL has been associated with neutropenia in patients with heart failure and multivessel atherosclerotic CAD. Left ventricular aneurysms were diagnosed in 15.8% (n=3) patients with low NGAL and in none with normal NGAL levels. These changes may be due to maladaptive remodeling of the heart after myocardial infarction, but further research is needed.

Increased urinary markers of kidney damage in the institutionalized frail elderly due to recurrent urinary tract infections

Objective:

To characterize the impact on kidney injury of recurrent urinary tract infections (RUTI) in the frail elderly.

Methods:

Prospective observational study in 200 frail elderly subjects for 1 year. Groups: GA (n = 100): subjects without RUTI, GB (n = 100): subjects with RUTI. Variables: age, concomitant diseases, glomerular filtration rate (GFR), urine neutrophil gelatinase-associated lipocalin (NGAL) at the beginning (NGAL-1) and end (NGAL-2) of the study, urine N-acetyl glucosaminidase (NAG) at the beginning (NAG-1) and the end (NAG-2) of the study, urine transforming growth factor-beta 1 (TGFβ-1). Descriptive statistics, Mann–Whitney test, Chi-squared test, Fisher’s exact test, and multivariate analysis were used.

Results:

Mean age was 84.33 (65–99) years old, with no difference between GA and GB. Mean NGAL-1 was 1.29 ng/ml (0.04–8). There was lower in GA than in GB. Mean NGAL-2 was 1.41 ng/ml (0.02–9.22). NGAL-2 was lower in GA than in GB. Mean NAG-1 was 0.38 UU.II/ml (0.01–2.63. NAG-1 in GA was lower than in GB. Mean NAG-2 was 0.44 UU.II/ml (0–3.41). NAG-2 was lower in GA compared with GB. Mean TGFβ-1 was 23.43 pg/ml (0.02–103.76). TGFβ-1 was lower in GA than GB. There were no differences in the presence of secondary diagnoses between GA and GB. NAG-2 and NGAL-1 were the most determining factors of renal function; in GA it was NGAL-2, followed by NAG-1; in GB it was NGAL-1, followed by NAG-2.

Conclusion:

Frail elderly with RUTI have higher urinary levels of renal injury markers, specifically NGAL, NAG, and TGFβ-1, chronically in periods between urinary tract infection (UTI). Urinary markers of renal injury, specifically NGAL, NAG, and TGFβ-1, identify early deterioration of renal function, compared with serum creatinine, or albuminuria, in frail elderly with recurrent urinary infections.

Lipocalin-2-The myth of its expression and function

Lipocalin-2 is a functional biomarker for acute and chronic kidney diseases, heart failure and obesity-related medical complications. It is rapidly induced in epithelial cells under stress conditions, but constitutively produced from pre-adipocytes and mature adipocytes. Measuring the lipocalin-2 levels represents an effective approach for risk prediction, patient stratification and disease management. Nevertheless, due to ligand-binding, post-translational modification and protein-protein interaction, lipocalin-2 exists as multiple variants that elicit different pathophysiological functions. To characterize the specific structure-functional relationships of lipocalin-2 variants is critical for the development of biomarker assays with sufficient precision and reliability. Moreover, identifying the pathological forms of lipocalin-2 will provide new therapeutic targets and treatment approaches for obesity-related complications.