A combined-biomarker approach to clinical phenotyping renal dysfunction in heart failure

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.

Patient Selection and End Point Definitions for Decongestion Studies in Acute Decompensated Heart Failure: Part 1

Despite recent advances in the treatment of patients with chronic heart failure, acute decompensated heart failure remains associated with significant mortality and morbidity because many novel therapies have failed to demonstrate meaningful benefit. Persistent congestion in the setting of escalating diuretic therapy has been repeatedly shown to be a marker of poor prognosis and is currently being targeted by various emerging device-based therapies. Because these therapies inherently carry procedural risk, patient selection is key in the future trial design. However, it remains unclear which patients are at a higher risk of residual congestion or adverse outcomes despite maximally tolerated decongestive therapy. In the first part of this 2-part review, we aimed to outline patient risk factors and summarize current evidence for early recognition of high-risk profile for residual congestion and adverse outcomes. These factors are classified as relating to the following: (1) previous clinical course, (2) severity of congestion, (3) diuretic response, and (4) degree of renal impairment. We also aimed to provide an overview of key inclusion criteria in recent acute decompensated heart failure trials and investigational device studies and propose potential criteria for selection of high-risk patients in future trials.

Urine peptidome analysis in cardiorenal syndrome reflects molecular processes

The cardiorenal syndrome (CRS) is defined as the confluence of heart-kidney dysfunction. This study investigates the molecular differences at the level of the urinary peptidome between CRS patients and controls and their association to disease pathophysiology. The urinary peptidome of CRS patients (n = 353) was matched for age and sex with controls (n = 356) at a 1:1 ratio. Changes in the CRS peptidome versus controls were identified after applying the Mann-Whitney test, followed by correction for multiple testing. Proteasix tool was applied to investigate predicted proteases involved in CRS-associated peptide generation. Overall, 559 differentially excreted urinary peptides were associated with CRS patients. Of these, 193 peptides were specifically found in CRS when comparing with heart failure and chronic kidney disease urinary peptide profiles. Proteasix predicted 18 proteases involved in > 1% of proteolytic cleavage events including multiple forms of MMPs, proprotein convertases, cathepsins and kallikrein 4. Forty-four percent of the cleavage events were produced by 3 proteases including MMP13, MMP9 and MMP2. Pathway enrichment analysis supported that ECM-related pathways, fibrosis and inflammation were represented. Collectively, our study describes the changes in urinary peptides of CRS patients and potential proteases involved in their generation, laying the basis for further validation.

Accuracy of triggering receptor expressed on myeloid cells 1 in diagnosis and prognosis of acute myocardial infarction: a prospective cohort study

Background

Acute myocardial infarction (AMI) is one of the fatal cardiac emergencies. The detection of triggering receptor expressed on myeloid cells 1 (TREM1), a cell surface immunoglobulin that amplifies pro-inflammatory responses, screened by bioinformatics was shown to be significant in diagnosing and predicting the prognosis of AMI.

Methods

GSE66360, GSE61144 and GSE60993 were downloaded from the Gene Expression Omnibus (GEO) database to explore the differentially expressed genes (DEGs) between AMI and control groups using R software. A total of 147 patients in total were prospectively enrolled from October 2018 to June 2019 and divided into two groups, the normal group (n = 35) and the AMI group (n = 112). Plasma was collected from each patient at admission and all patients received 6-month follow-up care.

Results

According to bioinformatic analysis, TREM1 was an important DEG in patients with AMI. Compared with the normal group, TREM1 expression was markedly increased in the AMI group (p < 0.001). TREM1 expression was positively correlated with fasting plasma glucose (FPG), glycosylated hemoglobin (HbAC), and the number of lesion vessels, although it had no correlation with Gensini score. TREM1 expression in the triple-vessels group was significantly higher than that of the single-vessel group (p < 0.05). Multiple linear regression showed that UA and HbAC were two factors influencing TREM1 expression. The ROC curve showed that TREM1 had a diagnostic significance in AMI (p < 0.001), especially in AMI patients without diabetes. Cox regression showed increased TREM1 expression was closely associated with 6-month major adverse cardiac events (MACEs) (p < 0.001).

Conclusions

TREM1 is a potentially significant biomarker for the diagnosis of AMI and may be closely associated with the severity of coronary lesions and diabetes. TREM1 may also be helpful in predicting the 6-month MACEs after AMI.

Prognostic value of multimodal assessment of congestion in acute heart failure

BACKGROUND

A physical examination has limited performance in estimating systemic venous congestion and predicting mortality in patients with heart failure. We have evaluated the usefulness of the N-terminal prohormone of brain natriuretic peptide (NT-proBNP), cancer antigen 125 (CA125), lung ultrasound findings, relative plasma volume (rPV) estimation, and the urea/creatinine ratio as surrogate parameters of venous congestion and predictors of mortality.

METHODS

This work is a retrospective study of 203 patients admitted for acute heart failure in a tertiary hospital's internal medicine department with follow-up in a specialized outpatient clinic between 2013 and 2018. Clinical data were collected from hospital records. Treatment was decided upon according to the clinical judgment of each patient's attending physician. The main outcome measure was all-cause mortality at one year of follow-up.

RESULTS

Patients' mean age was 78.8 years and 47% were male. A total of 130 (65%) patients had chronic heart failure, 51 (26.2%) patients were in New York Heart Association class III-IV, and 116 (60%) patients had preserved left ventricular ejection fraction. During follow-up, 42 (22%) patients died. Values ??of NT-proBNP≥3,804pg/mL (HR 2.78 [1.27-6.08]; p=.010) and rPV ≥-4.54% (HR 2.74 [1.18-6.38]; p=.019) were independent predictors of all-cause mortality after one year of follow-up.

CONCLUSIONS

NT-proBNP and rPV are independent predictors of one-year mortality among patients hospitalized for decompensated heart failure.

Prognostic value of multimodal assessment of congestion in acute heart failure

BACKGROUND

A physical examination has limited performance in estimating systemic venous congestion and predicting mortality in patients with heart failure. We have evaluated the usefulness of the N-terminal prohormone of brain natriuretic peptide (NT-proBNP), cancer antigen 125 (CA125), lung ultrasound findings, relative plasma volume (rPV) estimation, and the urea/creatinine ratio as surrogate parameters of venous congestion and predictors of mortality.

METHODS

This work is a retrospective study of 203 patients admitted for acute heart failure in a tertiary hospital's internal medicine department with follow-up in a specialized outpatient clinic between 2013 and 2018. Clinical data were collected from hospital records. Treatment was decided upon according to the clinical judgment of each patient's attending physician. The main outcome measure was all-cause mortality at one year of follow-up.

RESULTS

Patients' mean age was 78.8 years and 47% were male. A total of 130 (65%) patients had chronic heart failure, 51 (26.2%) patients were in New York Heart Association class III-IV, and 116 (60%) patients had preserved left ventricular ejection fraction. During follow-up, 42 (22%) patients died. Values of NT-proBNP≥3804pg/mL (HR 2.78 [1.27-6.08]; p=.010) and rPV≥-4.54% (HR 2.74 [1.18-6.38]; p=.019) were independent predictors of all-cause mortality after one year of follow-up.

CONCLUSIONS

NT-proBNP and rPV are independent predictors of one-year mortality among patients hospitalized for decompensated heart failure.

Prognostic significance of acute kidney injury and small increases in creatinine concentration during acute decompensation of heart failure

BACKGROUND

Diagnosis of acute kidney injury (AKI) during acute decompensations of heart failure (ADHF) remain challenging. We analysed the incidence and prognosis of AKI, and the significance of small increases of creatinine, during ADHF and after stabilization.

PATIENTS AND METHODS

Patients admitted for ADHF were prospectively included. Creatinine was measured at admission, 48h thereafter and 24h before discharge. AKI was diagnosed when creatinine increased≥50% in 7 days (RIFLE criteria) or≥0.3mg/dL in 48h (AKIN criteria) during admission. Changes between baseline creatinine (measured within 3-month before admission) and one month after discharge were assessed, to seek for residual impairment of renal function and its significance.

RESULTS

Two hundred and four patients were included. Incidence of AKI was 28.4% (n=58). Creatinine peaked by day 5 in patients with AKI vs. non-AKI (1.9 vs. 1.1mg/dL; P<.000) and remained significantly higher among patients with AKI 3 months after discharge (increase of 20 vs. 4%; P=.013). Twelve-months mortality was associated with increases in cystatin C, NT-proBNP and AKI (15.5 vs. 44.8%, P<.000), being the latter the most powerful independent predictor of death ?Exp(B)=5.34; P=.009?. Minor increases in creatinine (20% or 0.2mg/dL) during admission associated lesser 12-months survival (P=.033 and P=.019, respectively). Increases in creatinine≥10% between baseline and one month after discharge are associated with higher mortality (12.6 vs. 22.5%, P=.044).

CONCLUSIONS

AKI is a strong predictor of mortality after ADHF. Minor increments in creatinine concentrations, below the accepted threshold for AKI definition, are prognostically meaningful.

Impacts of right ventricular function and venous congestion on renal response during depletion in acute heart failure

Aims

Venous congestion is a major determinant of worsening renal function (WRF) in acute decompensated heart failure (ADHF), particularly when associated with right ventricular (RV) dysfunction. Whether the individual impacts of hemodynamic variables on renal outcomes in ADHF is modified according to RV function remains unclear. We aimed to determine the association between hemodynamic parameters and early changes in renal function during depletive therapy and explore the association of these changes with clinical outcomes.

Methods and results

WRF was defined as any increase in creatinine after 24 h of depletive therapy and improvement in renal function (IRF) as any decrease. Assessments were prospectively obtained on admission, 24 h later and at discharge. Out of the 105 patients enrolled, 45% had IRF, and 41% had poor RV. At baseline, patients evolving towards IRF had a lower mean arterial pressure (84.7 ± 13.9 vs. 90.9 ± 15.2 mmHg), a lower renal perfusion pressure (69.4 ± 16.2 vs. 75.4 ± 15.1 mmHg), and a poorer RV function (tricuspid annular plan systolic excursion 16.5 ± 6.0 vs. 18.8 ± 5.6 mm) in comparison with those with WRF (all P < 0.05). In a multivariate linear regression model, tricuspid annular plane systolic excursion was the dominant parameter correlated with early changes in creatinine when RV was poor (β = 0.337), whereas mean arterial pressure (β = −0.334) and cardiac output (β = −0.298) were the only parameters correlated with renal function in patients with preserved RV function (all P < 0.05). RV dysfunction, but not early changes in renal function, was associated with post‐discharge clinical events.

Conclusions

RV dysfunction is a predictor of an early but transient progression to IRF during depletive therapy. RV dysfunction modifies the individual impact of various hemodynamic variables on the early trajectory of renal function in ADHF.

Renal Effects of Intensive Volume Removal in Heart Failure Patients With Preexisting Worsening Renal Function

Background The relationship between intensive volume removal in acute decompensated heart failure patients with preexisting worsening renal function (WRF) and renal tubular injury, postdischarge renal function, and clinical outcomes is unknown. Methods and Results We used data from the multicenter CARRESS-HF trial (Cardiorenal Rescue Study in Acute Decompensated Heart Failure) that randomized patients with acute decompensated heart failure and preexisting WRF to intensive volume removal with stepped pharmacological therapy or fixed rate ultrafiltration. Patients in the urinary renal tubular injury biomarker substudy (NAG [N-acetyl-b-D-glucosaminidase], KIM-1 [kidney injury molecule-1], and NGAL [neutrophil gelatinase-associated lipocalin]) were evaluated (N=105). The severity of prerandomization WRF was unrelated to baseline renal tubular injury biomarkers ( r=0.14; P=0.17). During randomized intensive volume removal, creatinine further worsened in 53% of patients. Despite a small to moderate magnitude increase in creatinine in most of these patients, postrandomization WRF was strongly associated with worsening in renal tubular injury biomarkers (odds ratio, 12.6; P=0.004). This observation did not differ by mode of volume removal (stepped pharmacological therapy versus ultrafiltration, P_interaction=0.46). Increase in renal tubular injury biomarkers was associated with a higher incidence of hemoconcentration (odds ratio, 3.1; P=0.015), and paradoxically, better recovery of creatinine at 60 days ( P=0.01). Conclusions In acute decompensated heart failure patients with preexisting WRF, intensive volume removal resulted in a further worsening of creatinine approximately half of the time, a finding associated with a rise in tubular injury biomarkers. However, decongestion and renal function recovery at 60 days were superior in patients with increased tubular injury markers. These data suggest that the benefits of decongestion may outweigh any modest or transient increases in serum creatinine or tubular injury markers that occur during intensive volume removal. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT00608491.

Protein biomarkers for cardiorenal syndrome

INTRODUCTION

The term cardiorenal syndrome (CRS) describes the progressive pathology and interactions that develop upon heart and kidney failure. The definition of CRS is not firmly established and has evolved gradually during the last decade. The main clinical challenges associated with CRS are the lack of tools for early disease diagnosis and the inability to predict the development of cardiorenal pathophysiology. Currently several biomarkers have been proposed for improving CRS patient management. However, validation studies are needed to implement these initial findings to the clinical setting. Areas covered: In this review the database PubMed was used for a literature search on the definition and classification of CRS as well as biomarkers for CRS diagnosis and prognosis. Expert opinion: A universally acceptable classification system for CRS is not available. Thus, acquiring mechanistic insights relative to the pathophysiology of the disease is challenging. Reported biomarkers include well-established markers for heart/renal dysfunction and inflammation. Some proteins expressed in both organs have also been associated with CRS, yet their link to disease pathophysiology and organ cross-talk is missing. Establishing the link between deregulated molecular pathways and CRS phenotypes is required to define biological relevance of existing findings and ultimately biology-driven markers and targets.

Relationship Between Level of Heart Type Fatty Acid Binding Protein (Before and after Procedures) with Acute Renal Failure after PCI in Patients Under PCI

BACKGROUND & OBJECTIVE

Acute renal failure (AKI) is one of the most important complications of PCI. Due to delay in creatinine increase, we need specific factors to detect AKI earlier. The aim of this study is to evaluate the valuable factors by focusing on HFAB-P that can be predictive for AKI after Percutaneous Coronary Intervention (PCI).

METHODS

This prospective study was performed on 95 patients (55 males and 44 females aged between 49-78 years) under PCI in Golestan and Imam Khomeini hospitals in Ahvaz. Patients were divided into three groups based on the development of AKI after the procedure: no AKI, severe AKI (doubling of serum creatinine or needing dialysis) and any type of AKI (increased creatinine ≥ 0/3 mg/dl or a 50% increase in the means of 1/5 times serum creatinine). The demographic and clinical characteristics of the patients, the medical history and the results of the HFABP marker, GFR, and creatinine before and after PCI were evaluated for all patients.

RESULTS

The progenies showed 6 patients with severe AKI, 17 patients with any type of AKI, and 72 patients without AKI. Diabetes (P = 0.003), hypertension (P = 0.027), gender of patients (P = 0.025) and hospital admission days (P <0.001) were significantly different among the groups. Patients' age and positive troponin were significantly higher in patients with AKI. HFABP was the only factor that had significant changes before and after PCI (P <0.001). The cut-off value of HFABP was 4.69 with 95.6% sensitivity and 84.7% specificity. It has a good negative predictive value of 98.39% which suggests it to be a good test for the AKI prediction. Glomerular Filtration Rate (GFR) and creatinine (Cr) were significantly different after PCI (P <0.001).

CONCLUSION

HFABP can be considered as a predictor for AKI after PCI. Moreover, our study suggests that evaluating several parameters such as Cr and GFR before and after PCI can predict the AKI development after PCI.

Toward Precision Medicine in the Cardiorenal Syndrome

Although the field of oncology has made significant steps toward individualized precision medicine, cardiology and nephrology still often use a "one size fits all" approach. This applies to the intersection of the heart-kidney interaction and the cardiorenal syndrome as well. Recent studies have shown that the prognostic implications of worsening renal function (WRF) in acute heart failure are variable; thus, there is a need to differentiate the implications of WRF to better guide precise care. This may best be performed with biomarkers that can give the clinician a real-time evaluation of the physiologic state at the time of developing WRF. This review will summarize current cardiac and renal biomarkers and their status in the evaluation of cardiorenal syndrome. Although we have made progress in our understanding of this syndrome, further investigation is needed to bring precision medicine into routine clinical practice for the care of patients with cardiorenal syndrome.

Renal function and acute heart failure outcome

The interaction between acute heart failure (AHF) and renal dysfunction is complex. Several studies have evaluated the prognostic value of this syndrome. The aim of this systematic review, which includes non-selected samples, was to investigate the impact of different renal function variables on the AHF prognosis. The categories included in the studies reviewed included: creatinine, blood urea nitrogen (BUN), the BUN/creatinine quotient, chronic kidney disease, the formula to estimate the glomerular filtration rate, criteria of acute renal injury and new biomarkers of renal damage such as neutrophil gelatinase-associated lipocalin (NGAL and cystatin c). The basal alterations of the renal function, as well as the acute alterations, transient or not, are related to a worse prognosis in AHF, it is therefore necessary to always have baseline, acute and evolutive renal function parameters.

Worsening Renal Function in Patients With Acute Heart Failure Undergoing Aggressive Diuresis Is Not Associated With Tubular Injury

BACKGROUND

Worsening renal function (WRF) in the setting of aggressive diuresis for acute heart failure treatment may reflect renal tubular injury or simply indicate a hemodynamic or functional change in glomerular filtration. Well-validated tubular injury biomarkers, N-acetyl-β-d-glucosaminidase, neutrophil gelatinase-associated lipocalin, and kidney injury molecule 1, are now available that can quantify the degree of renal tubular injury. The ROSE-AHF trial (Renal Optimization Strategies Evaluation-Acute Heart Failure) provides an experimental platform for the study of mechanisms of WRF during aggressive diuresis for acute heart failure because the ROSE-AHF protocol dictated high-dose loop diuretic therapy in all patients. We sought to determine whether tubular injury biomarkers are associated with WRF in the setting of aggressive diuresis and its association with prognosis.

METHODS

Patients in the multicenter ROSE-AHF trial with baseline and 72-hour urine tubular injury biomarkers were analyzed (n=283). WRF was defined as a ≥20% decrease in glomerular filtration rate estimated with cystatin C.

RESULTS

Consistent with protocol-driven aggressive dosing of loop diuretics, participants received a median 560 mg IV furosemide equivalents (interquartile range, 300-815 mg), which induced a urine output of 8425 mL (interquartile range, 6341-10 528 mL) over the 72-hour intervention period. Levels of N-acetyl-β-d-glucosaminidase and kidney injury molecule 1 did not change with aggressive diuresis (both P>0.59), whereas levels of neutrophil gelatinase-associated lipocalin decreased slightly (-8.7 ng/mg; interquartile range, -169 to 35 ng/mg; P<0.001). WRF occurred in 21.2% of the population and was not associated with an increase in any marker of renal tubular injury: neutrophil gelatinase-associated lipocalin (P=0.21), N-acetyl-β-d-glucosaminidase (P=0.46), or kidney injury molecule 1 (P=0.22). Increases in neutrophil gelatinase-associated lipocalin, N-acetyl-β-d-glucosaminidase, and kidney injury molecule 1 were paradoxically associated with improved survival (adjusted hazard ratio, 0.80 per 10 percentile increase; 95% confidence interval, 0.69-0.91; P=0.001).

CONCLUSIONS

Kidney tubular injury does not appear to have an association with WRF in the context of aggressive diuresis of patients with acute heart failure. These findings reinforce the notion that the small to moderate deteriorations in renal function commonly encountered with aggressive diuresis are dissimilar from traditional causes of acute kidney injury.

Ultrasonic evaluation of renal cortex arterial area enables differentiation between hypertensive and glomerulonephritis-related chronic kidney disease

PURPOSE

Identifying the primary etiology of cardio-renal syndrome in a timely manner remains an ongoing challenge in nephrology. We hypothesized that hypertensive kidney damage can be distinguished from chronic glomerulonephritis at an early stage of chronic kidney disease (CKD) using ultrasound (US) Doppler sonography.

METHODS

Fifty-six males (age 54 ± 15, BMI 28.3 ± 3.5 kg/m2) with hypertension and stable CKD at stages 2-4 [38 with essential hypertension (HT-CKD); 18 with glomerulonephritis (GN-CKD)] were studied. Blood tests, UACR, echocardiography, ABPM, carotid IMT, and an ultrasound dynamic tissue perfusion measurement (DTPM) of the renal cortex were performed.

RESULTS

HT-CKD patients had reduced proximal renal cortex perfusion as well as reduced total and proximal renal cortex arterial area. Proximal renal cortex arterial area ≤0.149 cm2 identified hypertension-related CKD with a sensitivity of 71% and a specificity of 78% (AUC 0.753, p < 0.001).

CONCLUSIONS

Evidence of diminished arterial vascularity or perfusion of renal proximal cortex, both derived from US Doppler, could be helpful in differentiating hypertensive nephropathy from glomerulonephritis-related CKD.

Acute Kidney Injury in Heart Failure Revisited-The Ameliorating Impact of "Decongestive Diuresis" on Renal Dysfunction in Type 1 Acute Cardiorenal Syndrome: Accelerated Rising Pro B Naturetic Peptide Is a Predictor of Good Renal Prognosis

There is mounting evidence that forward heart failure as manifested by low cardiac output alone does not define the degree of renal dysfunction in cardiorenal syndrome. As a result, the term “congestive renal failure” was coined in 2012 by Ross to depict the role of renal venous hypertension in type 1 acute cardiorenal syndrome. If so, aggressive decongestive therapies, either through mechanical ultrafiltration with dialysis machines or pharmacologic ultrafiltration with potent diuretics, would lead to improved cardio and renal outcomes. Nevertheless, as recently as 2012, a review of this literature had concluded that a renal venous hypertension-directed approach using diuretics to manage cardio-renal syndrome was yet to be fully investigated. We, in this review, with three consecutive case series, describe our experience with pharmacologic decongestive diuresis in this paradigm of care and argue for studies of such therapeutic interventions in the management of cardiorenal syndrome. Finally, based on our observations in the Renal Unit, Mayo Clinic Health System, in Northwestern Wisconsin, we have hypothesized that patients with cardiorenal syndrome presenting with accelerated rising Pro B Naturetic Peptide levels appear to represent a group that would have good cardio- and renal-outcomes with such decongestive pharmacologic therapies.

Acute coronary syndrome and acute kidney injury: role of inflammation in worsening renal function

Background

Acute Kidney Injury (AKI), a common complication of acute coronary syndromes (ACS), is associated with higher mortality and longer hospital stays. The role of cytokines and other mediators is unknown in AKI induced by an ACS (ACS-AKI), leading to several unanswered questions. The worsening of renal function is usually seen as a dichotomous phenomenon instead of a dynamic change, so evaluating changes of the renal function in time may provide valuable information in the ACS-AKI setting. The aim of this study was to explore inflammatory factors associated to de novo kidney injury induced by de novo cardiac injury secondary to ACS.

Methods

One hundred four consecutive patients with ACS were initially included on the time of admission to the Coronary Unit of the Instituto Nacional de Cardiología in Mexico City, from February to May 2016, before any invasive procedure, imaging study, diuretic or anti-platelet therapy. White blood count, hemoglobin, NT-ProBNP, troponin I, C-reactive protein, albumin, glucose, Na⁺, K⁺, blood urea nitrogen (BUN), total cholesterol, HDL, LDL, triglycerides, creatinine (Cr), endothelin-1 (ET-1), leukotriene-B4, matrix metalloproteinase-2 and -9, tissue inhibitor of metalloproteinases-1, resolvin-D1 (RvD1), lipoxin-A4 (LXA4), interleukin-1β, −6, −8, and −10 were measured. We finally enrolled 78 patients, and subsequently we identified 15 patients with ACS-AKI. Correlations were obtained by a Spearman rank test. Low-rank regression, splines regressions, and also protein–protein/chemical interactions and pathways analyses networks were performed.

Results

Positive correlations of ΔCr were found with BUN, admission Cr, GRACE score, IL-1β, IL-6, NT-ProBNP and age, and negative correlations with systolic blood pressure, mean-BP, diastolic-BP and LxA4. In the regression analyses IL-10 and RvD1 had positive non-linear associations with ΔCr. ET-1 had also a positive association. Significant non-linear associations were seen with NT-proBNP, admission Cr, BUN, Na⁺, K⁺, WBC, age, body mass index, GRACE, SBP, mean-BP and Hb.

Conclusion

Inflammation and its components play an important role in the worsening of renal function in ACS. IL-10, ET-1, IL-1β, TnI, RvD1 and LxA4 represent mediators that might be associated with ACS-AKI. IL-6, ET-1, NT-ProBNP might represent crossroads for several physiopathological pathways involved in “de novo cardiac injury leading to de novo kidney injury”.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-017-0640-0) contains supplementary material, which is available to authorized users.

Renal function assessment in heart failure

Renal function is one of the most consistent prognostic determinants in heart failure. The prognostic information it provides is independent of the ejection fraction and functional status. This article reviews the various renal function assessment measures, with special emphasis on the fact that the patient's clinical situation and response to the heart failure treatment should be considered for the correct interpretation of the results. Finally, we review the literature on the performance of tubular damage biomarkers.

Chronic Heart Failure and Comorbid Renal Dysfunction - A Focus on Type 2 Cardiorenal Syndrome

The most important advancements in the Cardiorenal syndrome (CRS) are its definition and subsequent classifications. When the predominant pathology and pathophysiology is the heart, i.e. chronic heart failure (CHF), and where any renal impairment (RI) subsequent to this is secondary, the classification is type 2 CRS. There are unique differences in the pathophysiology and progression of individual subclasses. It is important to understand the evolution of CHF and consequences of subsequent RI as they are becoming increasingly prevalent, aggravate morbidity and mortality and limit many therapeutic options. In this paper we discuss the significance of the type 2 CRS patients in the context of the thematic series.

A Clinical Approach to the Acute Cardiorenal Syndrome

Acute kidney injury is a frequent complication of acute heart failure syndromes, portending an adverse prognosis. Acute cardiorenal syndrome represents a unique form of acute kidney injury specific to acute heart failure syndromes. The pathophysiology of acute cardiorenal syndrome involves renal venous congestion, ineffective forward flow, and impaired renal autoregulation caused by neurohormonal activation. Biomarkers reflecting different aspects of acute cardiorenal syndrome pathophysiology may allow patient phenotyping to inform prognosis and treatment. Adjunctive vasoactive, neurohormonal, and diuretic therapies may relieve congestive symptoms and/or improve renal function, but no single therapy has been proved to reduce mortality in acute cardiorenal syndrome.

The risk of death associated with proteinuria in heart failure is restricted to patients with an elevated blood urea nitrogen to creatinine ratio

BACKGROUND

Renal dysfunction (RD) is associated with reduced survival in HF; however, not all RD is mechanistically or prognostically equivalent. Notably, RD associated with "pre-renal" physiology, as identified by an elevated blood urea nitrogen to creatinine ratio (BUN/Cr), identifies a particularly high risk RD phenotype. Proteinuria, another domain of renal dysfunction, has also been associated with adverse events. Given that several different mechanisms can cause proteinuria, we sought to investigate whether the mechanism underlying proteinuria also affects survival in HF.

METHODS AND RESULTS

Subjects in the Studies of Left Ventricular Dysfunction (SOLVD) trial with proteinuria assessed at baseline were studied (n=6439). All survival models were adjusted for baseline characteristics and estimated glomerular filtration rate (eGFR). Proteinuria (trace or 1+) was present in 26% and associated with increased mortality (HR=1.2; 95% CI, 1.1-1.3, p=0.006). Proteinuria >1+ was less common (2.5%) but demonstrated a stronger relationship with mortality (HR=1.9; 95% CI, 1.5-2.5, p<0.001). In patients with BUN/Cr in the top tertile (≥17.3), any proteinuria (HR=1.3; 95% CI, 1.1-1.5, p=0.008) and >1+ proteinuria (HR=2.3; 95% CI, 1.7-3.3, p<0.001) both remained associated with mortality. However, in patients with BUN/Cr in the bottom tertile (≤13.3), any proteinuria (HR=0.95; 95% CI, 0.77-1.2, p=0.63, p interaction=0.015) and >1+ proteinuria (HR=1.3; 95% CI, 0.79-2.2, p=0.29, p interaction=0.036) were not associated with worsened survival.

CONCLUSION

Analogous to a reduced eGFR, the mechanism underlying proteinuria in HF may be important in determining the associated survival disadvantage.

Biomarkers of renal injury and function: diagnostic, prognostic and therapeutic implications in heart failure

Heart failure guidelines suggest evaluating renal function as a routine work-up in every patient with heart failure. Specifically, it is advised to calculate glomerular filtration rate and determine blood urea nitrogen. The reason for this is that renal impairment and worsening renal function (WRF) are common in heart failure, and strongly associate with poor outcome. Renal function, however, consists of more than glomerular filtration alone, and includes tubulointerstitial damage and albuminuria. For each of these renal entities, different biomarkers exist that have been investigated in heart failure. Hypothetically, and in parallel to data in nephrology, these markers may aid in the diagnosis of renal dysfunction, or for risk stratification, or could help in therapeutic decision-making. However, as reviewed in the present manuscript, while these markers may carry prognostic information (although not always additive to established markers of renal function), their role in predicting WRF is limited at best. More importantly, none of these markers have been evaluated as a therapeutic target nor have their serial values been used to guide therapy. The evidence is most compelling for the oldest-serum creatinine (in combination with glomerular filtration rate)-but even for this biomarker, evidence to guide therapy to improve outcome is circumstantial at best. Although many new renal biomarkers have emerged at the horizon, they have only limited usefulness in clinical practice until thoroughly and prospectively studied. For now, routine measurement of (novel) renal biomarkers can help to determine cardiovascular risk, but there is no role for these biomarkers to change therapy to improve clinical outcome in heart failure.

Loop diuretics in acute heart failure: beyond the decongestive relief for the kidney

Current goals in the acute treatment of heart failure are focused on pulmonary and systemic decongestion with loop diuretics as the cornerstone of therapy. Despite rapid relief of symptoms in patients with acute decompensated heart failure, after intravenous use of loop diuretics, the use of these agents has been consistently associated with adverse events, including hypokalemia, azotemia, hypotension, and increased mortality. Two recent randomized trials have shown that continuous infusions of loop diuretics did not offer benefit but were associated with adverse events, including hyponatremia, prolonged hospital stay, and increased rate of readmissions. This is probably due to the limitations of congestion evaluation as well as to the deleterious effects linked to drug administration, particularly at higher dosage. The impaired renal function often associated with this treatment is not extensively explored and could deserve more specific studies. Several questions remain to be answered about the best diuretic modality administration, global clinical impact during acute and post-discharge period, and the role of renal function deterioration during treatment. Thus, if loop diuretics are a necessary part of the treatment for acute heart failure, then there must be an approach that allows personalization of therapy for optimal benefit and avoidance of adverse events.

Kidney disease in heart failure: the importance of novel biomarkers for type 1 cardio-renal syndrome detection

Chronic kidney disease (CKD) in heart failure (HF) has been recognized as an independent risk factor for adverse outcome, although the most important clinical trials tend to exclude patients with moderate and severe renal insufficiency. Despite this common association, the precise pathophysiological connection and liaison between heart and kidney is partially understood. Moreover, is it not enough considering how much cardio-renal syndrome type 1 is attributable to previous CKD, and how much to new-onset acute kidney injury (AKI). Neither development of AKI, its progression and time nor duration is related to an adverse outcome. An AKI definition is not universally recognized, and many confounding terms have been used in literature: "worsening renal function", "renal impairment", "renal dysfunction", etc., are all names that contribute to misunderstanding, and do not facilitate an universal classification. Therefore, AKI development should be the consequence of the basal clinical characteristics of patients, different primitive kidney disease and hemodynamic status. AKI could also be the mirror of several underlying associated diseases poorly controlled. Finally, it is not clear which is the optimal laboratory tool for identifying patients with an increased risk of AKI. In the current report, we review the different kidney diseases' impact in HF, and we analyze the modalities for AKI recognition during HF focusing our attention about some new biomarkers with potential application in the current setting.

The kidney in heart failure: an update

Heart and kidney are closely related in the clinical syndrome of heart failure (HF). It is now sufficiently clear that renal dysfunction occurs frequently in all phenotypes of HF, and when present, it is associated with higher mortality and morbidity. While the pathophysiology is multifactorial, the most important factors are a reduced renal perfusion and venous congestion. Recent interest has focused on worsening renal function (WRF), a situation strongly related to mortality, but seemingly only when HF status deteriorates. Unfortunately, to date clinicians are unable to identify specifically those patients with a grim prognosis following WRF. Although much has been learned on cardiorenal interaction in HF, still more questions have been left unanswered. The coming decade should provide us with more dedicated epidemiologic, mechanistic, and controlled trials in HF patients with reduced renal function. An updated classification of the cardiorenal syndrome that incorporates recent evidence and points towards areas of interest and uncertainties, and areas where progress is needed could facilitate this process. Ultimately, this should lead to preventive and treatment strategies that can preserve renal function and associated outcome in patients with HF.

Pathogenesis and treatment of the cardiorenal syndrome: Implications of L-arginine-nitric oxide pathway impairment

A highly complex interplay exists between the heart and kidney in the setting of both normal and abnormal physiology. In the context of heart failure, a pathophysiological condition termed the cardiorenal syndrome (CRS) exists whereby dysfunction in the heart or kidney can accelerate pathology in the other organ. The mechanisms that underpin CRS are complex, and include neuro-hormonal activation, oxidative stress and endothelial dysfunction. The endothelium plays a central role in the regulation of both cardiac and renal function, and as such impairments in endothelial function can lead to dysfunction of both these organs. In particular, reduced bioavailability of nitric oxide (NO) is a key pathophysiologic component of endothelial dysfunction. The synthesis of NO by the endothelium is critically dependent on the plasmalemmal transport of its substrate, L-arginine, via the cationic amino acid transporter-1 (CAT1). Impaired L-arginine-NO pathway activity has been demonstrated individually in heart and renal failure. Recent findings suggest abnormalities of the L-arginine-NO pathway also play a role in the pathogenesis of CRS and thus this pathway may represent a potential new target for the treatment of heart and renal failure.

Perioperative heart-type fatty acid binding protein is associated with acute kidney injury after cardiac surgery

Acute Kidney Injury (AKI) is a common complication after cardiac surgery and is associated with worse outcomes. Since heart fatty acid binding protein (H-FABP) is a myocardial protein that detects cardiac injury, we sought to determine if plasma H-FABP was associated with AKI in the TRIBE-AKI cohort; a multi-center cohort of 1219 patients at high risk for AKI who underwent cardiac surgery. The primary outcomes of interest were any AKI (Acute Kidney Injury Network (AKIN) stage 1 or higher) and severe AKI (AKIN stage 2 or higher). The secondary outcome was long-term mortality after discharge. Patients who developed AKI had higher levels of H-FABP pre- and post-operatively than patients who did not have AKI. In analyses adjusted for known AKI risk factors, first post-operative log(H-FABP) was associated with severe AKI (adjusted OR 5.39 [95% CI, 2.87-10.11] per unit increase), while pre-operative log(H-FABP) was associated with any AKI (2.07 [1.48-2.89]) and mortality (1.67 [1.17-2.37]). These relationships persisted after adjustment for change in serum creatinine (for first postoperative log(H-FABP)) and biomarkers of cardiac and kidney injury, including brain natriuretic peptide, cardiac troponin-I, interleukin-18, liver fatty acid binding protein, kidney injury molecule-1, and neutrophil gelatinase associated lipocalin. Thus, peri-operative plasma H-FABP levels may be used for risk-stratification of AKI and mortality following cardiac surgery.