Cardiorenal syndrome in acute decompensated heart failure

Cardiorenal syndrome: Plasmonic biosensors

Cardiorenal syndrome (CRS) is defined as a broad spectrum of conditions encompassing both the heart and kidneys in which acute or chronic heart disorder may induce acute or chronic tubular injury in the kidneys and vice versa. Early diagnosis allows timely intervention and attenuates disease progression. Two well-established biomarkers, neutrophil gelatinase-associated lipocalin (NGAL) and brain (B-type) natriuretic peptide (BNP), are reflective of impaired cardiac and kidney function associated with poor prognosis in various cardiac disorders, including heart failure and coronary artery disease. Given the ongoing contribution of CRS to the high morbidity and mortality post-MI, early risk stratification and preventive measures are highly significant. In this review, we examine Surface Plasmon Resonance (SPR) optical biosensors for detection of these biomarkers and discuss potential implications of this highly sensitive and specific technology in CRS detection, treatment and outcomes.

Impact of Renal Congestion in Patients With Secondary Mitral Regurgitation After Mitral Transcatheter Edge-to-Edge Repair

BACKGROUND

Renal congestion is a potential prognostic factor in patients with heart failure and recently, assessment has become possible with intrarenal Doppler ultrasonography (IRD). The association between renal congestion assessed by IRD and outcomes after mitral transcatheter edge-to-edge repair (TEER) is unknown, so we aimed to clarify renal congestion and its prognostic implications in patients with mitral regurgitation (MR) who underwent TEER using MitraClip system.Methods and Results: Patients with secondary MR who underwent TEER and were assessed for intrarenal venous flow (IRVF) by IRD were classified according to their IRVF pattern as continuous or discontinuous. Of the 105 patients included, 78 patients (74%) formed the continuous group and 27 (26%) were the discontinuous group. Kaplan-Meier analysis revealed significant prognostic power of the IRVF pattern for predicting the composite outcome of all-cause death and heart failure rehospitalization (log-rank P=0.0257). On multivariate Cox regression analysis, the composite endpoint was independently associated with the discontinuous IRVF pattern (hazard ratio, 3.240; 95% confidence interval, 1.300-8.076; P=0.012) adjusted using inverse probability of treatment weighting.

CONCLUSIONS

IRVF patterns strongly correlated with clinical outcomes without changes in renal function. Thus, they may be useful for risk stratification after mitral TEER for patients with secondary MR.

Edema formation in congestive heart failure and the underlying mechanisms

Congestive heart failure (HF) is a complex disease state characterized by impaired ventricular function and insufficient peripheral blood supply. The resultant reduced blood flow characterizing HF promotes activation of neurohormonal systems which leads to fluid retention, often exhibited as pulmonary congestion, peripheral edema, dyspnea, and fatigue. Despite intensive research, the exact mechanisms underlying edema formation in HF are poorly characterized. However, the unique relationship between the heart and the kidneys plays a central role in this phenomenon. Specifically, the interplay between the heart and the kidneys in HF involves multiple interdependent mechanisms, including hemodynamic alterations resulting in insufficient peripheral and renal perfusion which can lead to renal tubule hypoxia. Furthermore, HF is characterized by activation of neurohormonal factors including renin-angiotensin-aldosterone system (RAAS), sympathetic nervous system (SNS), endothelin-1 (ET-1), and anti-diuretic hormone (ADH) due to reduced cardiac output (CO) and renal perfusion. Persistent activation of these systems results in deleterious effects on both the kidneys and the heart, including sodium and water retention, vasoconstriction, increased central venous pressure (CVP), which is associated with renal venous hypertension/congestion along with increased intra-abdominal pressure (IAP). The latter was shown to reduce renal blood flow (RBF), leading to a decline in the glomerular filtration rate (GFR). Besides the activation of the above-mentioned vasoconstrictor/anti-natriuretic neurohormonal systems, HF is associated with exceptionally elevated levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). However, the supremacy of the deleterious neurohormonal systems over the beneficial natriuretic peptides (NP) in HF is evident by persistent sodium and water retention and cardiac remodeling. Many mechanisms have been suggested to explain this phenomenon which seems to be multifactorial and play a major role in the development of renal hyporesponsiveness to NPs and cardiac remodeling. This review focuses on the mechanisms underlying the development of edema in HF with reduced ejection fraction and refers to the therapeutic maneuvers applied today to overcome abnormal salt/water balance characterizing HF.

The interstitial compartment as a therapeutic target in heart failure

Congestion is the single most important contributor to heart failure (HF) decompensation. Most of the excess volume in patients with HF resides in the interstitial compartment. Inadequate decongestion implies persistent interstitial congestion and is associated with worse outcomes. Therefore, effective interstitial decongestion represents an unmet need to improve quality of life and reduce clinical events. The key processes that underlie incomplete interstitial decongestion are often ignored. In this review, we provide a summary of the pathophysiology of the interstitial compartment in HF and the factors governing the movement of fluids between the interstitial and vascular compartments. Disruption of the extracellular matrix compaction occurs with edema, such that the interstitium becomes highly compliant, and large changes in volume marginally increase interstitial pressure and allow progressive capillary filtration into the interstitium. Augmentation of lymph flow is required to prevent interstitial edema, and the lymphatic system can increase fluid removal by at least 10-fold. In HF, lymphatic remodeling can become insufficient or maladaptive such that the capacity of the lymphatic system to remove fluid from the interstitium is exceeded. Increased central venous pressure at the site of the thoracic duct outlet also impairs lymphatic drainage. Owing to the kinetics of extracellular fluid, microvascular absorption tends to be transient (as determined by the revised Starling equation). Therefore, effective interstitial decongestion with adequate transcapillary plasma refill requires a substantial reduction in plasma volume and capillary pressure that are prolonged and sustained, which is not always achieved in clinical practice. The critical importance of the interstitium in the congestive state underscores the need to directly decongest the interstitial compartment without relying on the lowering of intracapillary pressure with diuretics. This unmet need may be addressed by novel device therapies in the near future.

Levosimendan Administration May Provide More Benefit for Survival in Patients with Non-Ischemic Cardiomyopathy Experiencing Acute Decompensated Heart Failure

Background: Acute decompensated heart failure (ADHF) is a life-threatening condition with a high mortality rate. Levosimendan is an effective inotropic agent used to maintain cardiac output and a long-lasting effect. However, only few studies have compared the clinical outcomes, after levosimendan therapy, among etiologies of ADHF. Methods: Between July 2014 and December 2019, 184 patients received levosimendan therapy for ADHF at our hospital. A total of 143 patients had ischemic cardiomyopathy (ICM), and 41 patients had non-ICM (NICM). Data on comorbidities, echocardiographic findings, laboratory findings, use of mechanical devices, consumption of other inotropic or vasopressor agents, frequency of HF hospitalization, cardiovascular (CV) mortality, and all-cause mortality were compared between the ICM and NICM groups. Results: Patients with ICM were older with higher prevalence of diabetes mellitus when compared to patients with NICM. Patients with NICM had a poorer left ventricular ejection fraction (LVEF) and higher left ventricular end-systolic volume when compared to patients with ICM. At the 30 day follow-up period, a lower CV mortality (ICM vs. NICM: 20.9% vs. 5.1%; log-rank p = 0.033) and lower all-cause mortality (ICM vs. NICM: 28.7% vs. 9.8%; log-rank p = 0.018) was observed in the NICM patients. A significantly lower all-cause mortality was noted at 180 day (ICM vs. NICM: 39.2% vs. 22.0%; log-rank p = 0.043) and 1 year (ICM vs. NICM: 41.3% vs. 24.4%; log-rank p = 0.046) follow up in the NICM subgroup. NICM (hazard ratio (HR): 0.303, 95% confidence interval (CI): 0.108–0.845; p = 0.023) and ECMO use (HR: 2.550, 95% CI: 1.385–4.693; p = 0.003) were significant predictors of 30 day all-cause mortality. Conclusions: In our study on levosimendan use for ADHF patients, better clinical outcomes were noted in the NICM population when compared to the ICM population. In the patients with cardiogenic shock or ventilator use, significantly lower incidence of 30 day mortality presented in the NICM population when compared with the ICM population.

Vitamin D Binding Protein and Renal Injury in Acute Decompensated Heart Failure

Background

Renal function in acute decompensated heart faiulre (ADHF) is a strong predictor of disease evolution and poor outcome. Current biomarkers for early diagnostic of renal injury in the setting of ADHF are still controversial, and their association to early pathological changes needs to be established. By applying a proteomic approach, we aimed to identify early changes in the differential urine protein signature associated with development of renal injury in patients hospitalised due to ADHF.

Materials and Methods

Patients (71 [64–77] years old) admitted at the emergency room with ADHF and hospitalised were investigated (N = 64). Samples (urine/serum) were collected at hospital admission (day 0) and 72 h later (day 3). Differential serum proteome was analysed by two-dimensional electrophoresis and matrix-assisted laser desorption/ionisation-time of flight (MALDI-ToF/ToF). Validation studies were performed using ELISA.

Results

Proteomic analysis depicted urinary vitamin D binding protein (uVDBP) as a two spots protein with increased intensity in ADHF and significant differences depending on the glomerular filtration rate (GFR). Urinary VDBP in patients with ADHF at hospitalisation was > threefold higher than in healthy subjects, with the highest levels in those patients with ADHF already presenting renal dysfunction. At day 3, urine VDBP levels in patients maintaining normal renal function dropped to normal values (P = 0.03 vs. day 0). In contrast, urine VDBP levels remained elevated in the group developing renal injury, with values twofold above the normal range (P < 0.05), while serum creatinine and GF levels were within the physiological range in this group. Urinary VDBP in ADHF positively correlated with markers of renal injury such as cystatin C and Kidney Injury Molecule 1 (KIM-1). By ROC analysis, urinary VDBP, when added to cystatin C and KIM-1, improved the prediction of renal injury in patients with ADHF.

Conclusion

We showed increased urine VDBP in patients with ADHF at hospital admission and a differential uVDBP evolution pattern at early stage of renal dysfunction, before pathological worsening of GFR is evidenced.

Value of Renal Vascular Doppler Sonography in Cardiorenal Syndrome Type 1

OBJECTIVES

Worsening of renal function in a patient with acute decompensated heart failure is called cardiorenal syndrome (CRS) type 1. Recent studies have shown an association of persistent systemic venous congestion with renal dysfunction. This trial was set up to investigate the changes of renal Doppler parameters with diuretic therapy in patients with CRS type 1.

METHODS

Cases of CRS type 1 were identified among patients hospitalized for decompensated heart failure. Serial measurements of the renal venous impedance index (VII) and arterial resistive index (ARI) were calculated by pulsed wave Doppler sonography.

RESULTS

A total of 30 patients who had creatinine improvement with diuresis (group 1) and 34 patients without any improvement (group 2) were analyzed. Patients in group 1 had higher median VII and ARI (VII, 0.86 versus 0.66; P < .001; ARI, 0.78 versus 0.65; P < .001) on admission. A high ARI on admission (odds ratio, 6.25; 95% confidence interval, 1.84-14.3; P = .003) predicted the improvement of serum creatinine levels with diuretic therapy independent of confounding factors in patients with CRS type 1.

CONCLUSIONS

Renal vascular Doppler parameters might offer guidance on the diagnostic and therapeutic strategies in prescribing decongestive therapy for decompensated heart failure.

Renal dysfunction in cardiovascular diseases and its consequences

It is well known that the heart and kidney and their synergy is essential for hemodynamic homeostasis. Since the early XIX century it has been recognized that cardiovascular and renal diseases frequently coexist. In the nephrological field, while it is well accepted that renal diseases favor the occurrence of cardiovascular diseases, it is not always realized that cardiovascular diseases induce or aggravate renal dysfunctions, in this way further deteriorating cardiac function and creating a vicious circle. In the same clinical field, the role of venous congestion in the pathogenesis of renal dysfunction is at times overlooked. This review carefully quantifies the prevalence of chronic and acute kidney abnormalities in cardiovascular diseases, mainly heart failure, regardless of ejection fraction, and the consequences of renal abnormalities on both organs, making cardiovascular diseases a major risk factor for kidney diseases. In addition, with regard to pathophysiological aspects, we attempt to substantiate the major role of fluid overload and venous congestion, including renal venous hypertension, in the pathogenesis of acute and chronic renal dysfunction occurring in heart failure. Furthermore, we describe therapeutic principles to counteract the major pathophysiological abnormalities in heart failure complicated by renal dysfunction. Finally, we underline that the mild transient worsening of renal function after decongestive therapy is not usually associated with adverse prognosis. Accordingly, the coexistence of cardiovascular and renal diseases inevitably means mediating between preserving renal function and improving cardiac activity to reach a better outcome.

Chronic elevation of renal venous pressure induces extensive renal venous collateral formation and modulates renal function and cardiovascular stability in rats

Acutely increased renal venous pressure (RVP) impairs renal function, but the long-term impact is unknown. We investigated whether chronic RVP elevation impairs baseline renal function and prevents exacerbation of renal dysfunction and cardiovascular instability upon further RVP increase. RVP elevation (20-25 mmHg) or sham operation (sham) was performed in rats. After 1 wk (n = 17) or 3 wk (n = 22), blood pressure, RVP, renal blood flow (RBF), renal vascular conductance (RVC), and glomerular filtration rate (GFR) were measured at baseline and during superimposed RVP increase. Chronic RVP elevation induced extensive renal venous collateral formation. RVP fell to 6 ± 1 mmHg at 1 wk and 3 ± 1 mmHg at 3 wk. Baseline blood pressure and heart rate were unaltered compared with sham. RBF, RVC, and GFR were reduced at 1 wk but normalized by 3 wk. Upon further RVP increase, the drop in mean arterial pressure was attenuated at 3 wk compared with 1 wk (P < 0.05), whereas heart rate fell comparably across all groups; the mean arterial pressure-heart rate relationship was disrupted at 1 and 3 wk. RBF fell to a similar degree as sham at 1 wk (-2.3 ± 0.7 vs. -3.9 ± 1.2 mL/min, P = 0.066); however, at 3 wk, this was attenuated compared with sham (-1.5 ± 0.5 vs. -4.2 ± 0.7 mL/min, P < 0.05). The drop in RVC and GFR was attenuated at 1 and 3 wk (P < 0.05). Thus, chronic RVP elevation induced by partial renal vein ligation elicits extensive renal venous collateral formation, and although baseline renal function is impaired, chronic RVP elevation in this manner induces protective adaptations in kidneys of healthy rats, which attenuates the hemodynamic response to further RVP increase.

Tidal peritoneal dialysis versus ultrafiltration in type 1 cardiorenal syndrome: A prospective randomized study

Background:

Ultrafiltration is an alternative strategy to diuretic therapy for the treatment of patients with acute decompensated heart failure. Little is known about the efficacy and safety of peritoneal dialysis in patients with acute decompensated heart failure complicated by acute cardiorenal syndrome.

Methods:

We randomly assigned a total of 88 patients with type 1 acute cardiorenal syndrome to a strategy of ultrafiltration therapy (44 patients) or tidal peritoneal dialysis (44 patients). The primary endpoint was the change from baseline in the serum creatinine level and left ventricular function represented as ejection fraction, as assessed 72 and 120 h after random assignment. Patients were followed for 90 days after discharge from the hospital.

Results:

Ultrafiltration therapy was inferior to tidal peritoneal dialysis therapy with respect to the primary endpoint of the change in the serum creatinine levels at 72 and 120 h ( p = 0.041) and ejection fraction at 72 and 120 h after enrollment ( p = 0.044 and p = 0.032), owing to both an increase in the creatinine level in the ultrafiltration therapy group and a decrease in its level in the tidal peritoneal dialysis group. At 120 h, the mean change in the creatinine level was 1.4 ± 0.5 mg/dL in the ultrafiltration therapy group, as compared with 2.4 ± 1.3 mg/dL in the tidal peritoneal dialysis group ( p = 0.023). At 72 and 120 h, there was a significant difference in weight loss between patients in the ultrafiltration therapy group and those in the tidal peritoneal dialysis group ( p = 0.025). Net fluid loss was also greater in tidal peritoneal dialysis patients ( p = 0.018). Adverse events were more observed in the ultrafiltration therapy group ( p = 0.007). At 90 days post-discharge, tidal peritoneal dialysis patients had fewer rehospitalization for heart failure (14.3% vs 32.5%, p = 0.022).

Conclusion:

Tidal peritoneal dialysis is a safe and effective means for removing toxins and large quantities of excess fluid from patients with intractable heart failure. In patients with cardiorenal syndrome type 1, the use of tidal peritoneal dialysis was superior to ultrafiltration therapy for the preservation of renal function, improvement of cardiac function, and net fluid loss. Ultrafiltration therapy was associated with a higher rate of adverse events.

Increased Intra-abdominal Pressure Induces Acute Kidney Injury in an Experimental Model of Congestive Heart Failure

BACKGROUND

Congestive heart failure (CHF) entails a complex interaction between the heart and the kidney that represents a clinical entity called cardiorenal syndrome (CRS). One of the mechanisms underlying CRS includes increased intra-abdominal pressure (IAP). We examined the effect of elevated IAP on kidney function in rats with low- and high-output CHF.

METHODS AND RESULTS

Rats with compensated and decompensated CHF induced by means of aortocaval fistula, rats with myocardial infraction (MI) induced by means of left anterior descending artery ligation, and sham control rats were subjected to either 10 or 14 mm Hg IAP. Urine flow (V), Na⁺ excretion (U_NaV), glomerular filtration rate (GFR), and renal plasma flow (RPF) were determined. The effects of pretreatment with tadalafil (10 mg/kg orally for 4 days) on the adverse renal effects of IAP were examined in decompensated CHF and MI. Basal V and GFR were significantly lower in rats with decompensated CHF compared with sham control rats. Decompensated CHF rats and MI rats subjected to 10 and 14 mm Hg IAP exhibited more significant declines in V, U_NaV, GFR and RPF than compensated and sham controls. Elevated IAP also induced tubular injury, as evidenced by significantly increased absolute urinary excretion of neutrophil gelatinase-associated lipocalin. In addition, in a nonquantitative histologic analysis, elevated IAP was associated with increase in necrosis and cell shedding to the tubule lumens, especially in the decompensated CHF subgroup. Pretreatment of decompensated CHF rats and MI rats with tadalafil ameliorated the adverse renal effects of high IAP.

CONCLUSIONS

Elevated IAP contributes to kidney dysfunction in high- and low-cardiac output CHF. IAP induces both hemodynamic alterations and renal tubular dysfunction. These deleterious effects are potentially reversible and can be ameliorated with the use of phosphodiesterase-5 inhibition.

Treatment patterns of patients with acute heart failure who develop acute kidney injury

AIMS

In the present study, we aimed to determine the relationship between therapeutic decisions during the treatment of acute heart failure (AHF) patients who develop acute kidney injury (AKI) and subsequent renal and clinical outcomes.

METHODS AND RESULTS

We studied 277 patients with AHF and AKI, defined as an increase of >0.3 mg/dL in serum creatinine. The physician response to AKI was determined through a treatment composite score that captured changes in medical management in response to AKI, including a reduction (≥50%) or discontinuation of selected medication classes [angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACE-Is/ARBs), beta-blockers, and diuretics] and fluids administration. ACE-Is/ARBs, beta-blockers, and diuretics were reduced or discontinued in 103 (55.4%), 84 (38.9%), and 166 (61.5%), respectively. Fluids were administered to 130 (46.9%) patients. Discontinuation rates of ACE-Is/ARBs, beta-blockers, diuretics, and fluids administration were higher in patients with hypotension (systolic blood pressure < 90 mm Hg; P = 0.001). In a logistic regression model, a composite score > 1 was associated with greater likelihood of renal function recovery (odds ratio 3.47, 95% confidence interval 2.06-5.83; P < 0.0001) but with a smaller reduction in congestion index (P = 0.021). Unadjusted 6 months mortality was higher in patients with a composite treatment score > 1 (hazard ratio 1.71, 95% confidence interval 1.12-2.61; P = 0.01). After adjustments, the treatment composite score was no longer associated with mortality.

CONCLUSIONS

Discontinuation or dose reduction of diuretics or neurohormonal blockers may improve renal outcome at the price of less efficient decongestion. Our results emphasize the need for randomized clinical trials that address the treatment of AHF patients with AKI.

Practical management of concomitant acute heart failure and worsening renal function in the emergency department

Worsening renal function (i.e. any increase in creatinine or decrease in the estimated glomerular filtration rate) is common in patients admitted for acute heart failure in the emergency department. Although worsening renal function (WRF) has been associated with the occurrence of dismal outcomes, this only appears to be the case when associated with clinical deterioration. However, if the clinical status of the patient is improving, a certain increase in serum creatinine may be acceptable. This WRF, which is not associated with clinical deterioration or adverse outcomes (e.g. during treatment up-titration), has been referred to as 'pseudo-WRF' and should not detract clinicians from targeting 'guideline-recommended' therapies. This is an important message for emergency physicians to pursue diuretics as long as signs of pulmonary congestion persist to improve the clinical status of the patient. In the present review, we aim to provide clinicians in acute settings with an integrative and comprehensive approach to cardiorenal interactions in acute heart failure.

Initiation and Cessation Timing of Renal Replacement Therapy in Patients with Type 1 Cardiorenal Syndrome: An Observational Study

BACKGROUND/AIMS

Renal replacement therapy (RRT) is a rescue therapy for patients with type 1 cardiorenal syndrome (CRS) with poor prognoses. However, the optimal timing for initiation and cessation of RRT remains controversial. The purpose of this study was to determine the optimal timing of initiation and cessation of RRT for patients with type 1 CRS.

METHODS

In this retrospective analysis, patients with refractory type 1 CRS receiving RRT were divided into 3 groups according to weaning from RRT and death within 90 days. Baseline characteristics, underlying heart disease, comorbidities, drug use before RRT, indicators of RRT initiation, and prognosis were compared between the 3 groups.

RESULTS

Fifty-two patients were enrolled, which included 27 males and 25 females with a mean age of 70.7 ± 16.1 years and a 90-day mortality rate of 65.4%. The mean urine output before RRT initiation was 800 mL/ 24 h in the RRT-independent group, 650 mL/24 h in the RRT-dependent group, and 345 mL/ 24 h in the death group (p = 0.021). Additionally, there were obvious differences in fluid balance between the 3 groups (167, 250, and 1,270 mL, respectively, p = 0.016). Patients could be successfully weaned from RRT when urine output was >880 mL and fluid balance volume was <150 mL.

CONCLUSION

The mean fluid balance of survivors was remarkably less than that of the death group at RRT initiation. RRT termination can be considered when urine output is >880 mL/24 h and volume balance is <150 mL/24 h.

Calibrating the impact of dual RAAS blockade on the heart and the kidney - balancing risks and benefits

Overactivity of the renin-angiotensin-aldosterone system (RAAS) plays a key role in the pathophysiology of heart failure (HF) and chronic kidney disease (CKD). RAAS antagonists can significantly improve clinical outcomes, but monotherapy blocks but one step of the RAAS and can be bypassed through compensatory mechanisms. Providing more complete RAAS blockade by deploying drugs with complementary actions seemed logical - hence the practice of using dual (or triple) RAAS inhibitors. However, RAAS antagonists also exhibit dose-limiting side effects, including acute kidney injury, hyperkalaemia and hypotension, which blunt their overall effectiveness. Despite achieving better RAAS blockade, several trials failed to show clinical outcome improvements. Patients with concomitant CKD and HF (cardiorenal syndrome) are at the greatest risk of these adverse events and therefore the least able to benefit, yet they also have the worst prognosis. This paradox, where those most in need have fewest therapeutic options, poses three questions which are the focus of this review: whether (i) novel therapies that prevent adverse effects can restore therapeutic benefits to patients who would otherwise be RAAS-therapy intolerant, (ii) there are any validated alternatives to their use and (iii) newer approaches to the detection of fluid congestion are ready for implementation.

Kidney Injury Molecule-1 and Cardiovascular Diseases: From Basic Science to Clinical Practice

Despite the recent findings concerning pathogenesis and novel therapeutic strategies, cardiovascular disease (CVD) still stays the leading cause of morbidity and mortality in patients with renal dysfunction, especially acute kidney injury (AKI). Early detection of patients with impaired renal function with cardiovascular risk may help ensure more aggressive treatment and improve clinical outcome. Kidney injury molecule-1 (KIM-1) is a new, promising marker of kidney damage which is currently the focus of countless studies worldwide. Some recent animal and human studies established KIM-1 as an important marker of acute tubular necrosis (ATN) and reliable predictor of development and prognosis of AKI. Food and Drug Administration (FDA) in USA acclaimed KIM-1 as an AKI biomarker for preclinical drug development. Recent data suggest the importance of monitoring of KIM-1 for early diagnosis and clinical course not only in patients with various forms of AKI and other renal diseases but also in patients with cardiorenal syndrome, heart failure, cardiopulmonary bypass, cardiothoracic surgical interventions in the pediatric emergency setting, and so forth. The aim of this review article is to summarize the literature data concerning KIM-1 as a potential novel marker in the early diagnosis and prediction of clinical outcome of certain cardiovascular diseases.

Focus on renal congestion in heart failure

Hospitalizations due to heart failure are increasing steadily despite advances in medicine. Patients hospitalized for worsening heart failure have high mortality in hospital and within the months following discharge. Kidney dysfunction is associated with adverse outcomes in heart failure patients. Recent evidence suggests that both deterioration in kidney function and renal congestion are important prognostic factors in heart failure. Kidney congestion in heart failure results from low cardiac output (forward failure), tubuloglomerular feedback, increased intra-abdominal pressure or increased venous pressure. Regardless of the cause, renal congestion is associated with increased morbidity and mortality in heart failure. The impact on outcomes of renal decongestion strategies that do not compromise renal function should be explored in heart failure. These studies require novel diagnostic markers that identify early renal damage and renal congestion and allow monitoring of treatment responses in order to avoid severe worsening of renal function. In addition, there is an unmet need regarding evidence-based therapeutic management of renal congestion and worsening renal function. In the present review, we summarize the mechanisms, diagnosis, outcomes, prognostic markers and treatment options of renal congestion in heart failure.

Interaction between worsening renal function and persistent congestion in acute decompensated heart failure

Worsening renal function (WRF) and congestion are inextricably related pathophysiologically, suggesting that WRF occurring in conjunction with persistent congestion would be associated with worse clinical outcome. We studied the interdependence between WRF and persistent congestion in 762 patients with acute decompensated heart failure (HF). WRF was defined as ≥0.3 mg/dl increase in serum creatinine above baseline at any time during hospitalization and persistent congestion as ≥1 sign of congestion at discharge. The primary end point was all-cause mortality with mean follow-up of 15 ± 9 months. Readmission for HF was a secondary end point. Persistent congestion was more common in patients with WRF than in patients with stable renal function (51.0% vs 26.6%, p <0.0001). Both persistent congestion and persistent WRF were significantly associated with mortality (both p <0.0001). There was a strong interaction (p = 0.003) between persistent WRF and congestion, such that the increased risk for mortality occurred predominantly with both WRF and persistent congestion. The adjusted hazard ratio for mortality in patients with persistent congestion as compared with those without was 4.16 (95% confidence interval [CI] 2.20 to 7.86) in patients with WRF and 1.50 (95% CI 1.16 to 1.93) in patients without WRF. In conclusion, persisted congestion is frequently associated with WRF. We have identified a substantial interaction between persistent congestion and WRF such that congestion portends increased mortality particularly when associated with WRF.

Cardiorenal Syndrome in Acute Heart Failure: Revisiting Paradigms

Cardiorenal syndrome has been defined as the simultaneous dysfunction of both the heart and the kidney. Worsening renal function that occurs in patients with acute heart failure has been classified as cardiorenal syndrome type 1. In this setting, worsening renal function is a common finding and is due to complex, multifactorial, and not fully understood processes involving hemodynamic (renal arterial hypoperfusion and renal venous congestion) and nonhemodynamic factors. Traditionally, worsening renal function has been associated with worse outcomes, but recent findings have revealed mixed and heterogeneous results, perhaps suggesting that the same phenotype represents a diversity of pathophysiological and clinical situations. Interpreting the magnitude and chronology of renal changes together with baseline renal function, fluid overload status, and clinical response to therapy might help clinicians to unravel the clinical meaning of renal function changes that occur during an episode of heart failure decompensation. In this article, we critically review the contemporary evidence on the pathophysiology and clinical aspects of worsening renal function in acute heart failure.

Deleterious Effects of Increased Intra-Abdominal Pressure on Kidney Function

Elevated intra-abdominal pressure (IAP) occurs in many clinical settings, including sepsis, severe acute pancreatitis, acute decompensated heart failure, hepatorenal syndrome, resuscitation with large volume, mechanical ventilation with high intrathoracic pressure, major burns, and acidosis. Although increased IAP affects several vital organs, the kidney is very susceptible to the adverse effects of elevated IAP. Kidney dysfunction is among the earliest physiological consequences of increased IAP. In the last two decades, laparoscopic surgery is rapidly replacing the open approach in many areas of surgery. Although it is superior at many aspects, laparoscopic surgery involves elevation of IAP, due to abdominal insufflation with carbonic dioxide (pneumoperitoneum). The latter has been shown to cause several deleterious effects where the most recognized one is impairment of kidney function as expressed by oliguria and reduced glomerular filtration rate (GFR) and renal blood flow (RBF). Despite much research in this field, the systemic physiologic consequences of elevated IAP of various etiologies and the mechanisms underlying its adverse effects on kidney excretory function and renal hemodynamics are not fully understood. The current review summarizes the reported adverse renal effects of increased IAP in edematous clinical settings and during laparoscopic surgery. In addition, it provides new insights into potential mechanisms underlying this phenomenon and therapeutic approaches to encounter renal complications of elevated IAP.

Prognostic value of worsening renal function in outpatients with chronic heart failure

INTRODUCTION AND OBJECTIVES

Renal function impairment predicts poor survival in heart failure. Attention has recently shifted to worsening renal function, based mostly on serum creatinine and estimated glomerular filtration rate. We assessed the prognostic effect of worsening renal function in ambulatory heart failure patients.

METHODS

Data from 306 ambulatory patients were abstracted from medical files. Worsening renal function was based on the change in estimated glomerular filtration rate, serum creatinine and urea within 6 months of referral. Prognosis was assessed by the composite endpoint all-cause death or heart failure hospitalization, censored at 2 years. Hazard ratios were estimated for worsening renal function, adjusted for sex, age, diabetes, New York Heart Association class, left ventricular systolic dysfunction, medications and baseline renal function.

RESULTS

The agreement among definitions was fair, with kappa coefficients generally not surpassing 0.5. Worsening renal function was associated with poor outcome with adjusted hazard ratios (95% confidence interval) of 3.2 (1.8-5.9) for an increase of serum creatinine >0.3mg/dl; 2.2 (1.3-3.7) for an increase in serum urea >20mg/dl and 1.9 (1.1-3.3) for a decrease in estimated glomerular filtration rate >20%, independent of baseline renal function. The 2-year risk of death/heart failure hospitalization was approximately 50% in patients with an increase in serum creatinine or in serum urea; this positive predictive value was higher than for decreasing estimated glomerular filtration rate.

CONCLUSIONS

In conclusion, worsening renal function was significantly associated with a worse outcome. Different definitions identified different patients at risk and increasing creatinine/urea performed better than decreasing estimated glomerular filtration rate.

Comorbidity profiles and inpatient outcomes during hospitalization for heart failure: an analysis of the U.S. Nationwide inpatient sample

BACKGROUND

Treatment of heart failure (HF) is particularly complex in the presence of comorbidities. We sought to identify and associate comorbidity profiles with inpatient outcomes during HF hospitalizations.

METHODS

Latent mixture modeling was used to identify common profiles of comorbidities during adult hospitalizations for HF from the 2009 Nationwide Inpatient Sample (n = 192,327).

RESULTS

Most discharges were characterized by "common" comorbidities. A "lifestyle" profile was characterized by a high prevalence of uncomplicated diabetes, hypertension, chronic pulmonary disorders and obesity. A "renal" profile had the highest prevalence of renal disease, complicated diabetes, and fluid and electrolyte imbalances. A "neurovascular" profile represented the highest prevalence of cerebrovascular disease, paralysis, myocardial infarction and peripheral vascular disease. Relative to the common profile, the lifestyle profile was associated with a 15% longer length of stay (LOS) and 12% greater cost, the renal profile was associated with a 30% higher risk of death, 27% longer LOS and 24% greater cost, and the neurovascular profile was associated with a 45% higher risk of death, 34% longer LOS and 37% greater cost (all p < 0.001).

CONCLUSIONS

Comorbidity profiles are helpful in identifying adults at higher risk of death, longer length of stay, and accumulating greater costs during hospitalizations for HF.

Hyponatraemia predicts the acute (type 1) cardio-renal syndrome

AIMS

The acute (type 1) cardio-renal syndrome (CRS) refers to an acute worsening of heart function leading to worsening renal function (WRF), and frequently complicates acute decompensated heart failure (ADHF) and acute myocardial infarction (AMI). The aim of this study was to investigate whether hyponatraemia, a surrogate marker of congestion and haemodilution and of neurohormonal activation, could identify patients at risk for WRF.

METHODS AND RESULTS

We studied the association between hyponatraemia (sodium <136 mmol/L) and WRF (defined as an increase of >0.3 mg/dL in creatinine above baseline) in two separate cohorts: patients with ADHF (n = 525) and patients with AMI (n = 2576). Hyponatraemia on admission was present in 156 patients (19.7%) with ADHF and 461 patients (17.7%) with AMI. Hyponatraemia was more frequent in patients who subsequently developed WRF as compared with patients who did not, in both the ADHF (34.6% vs. 22.2%, P = 0.0003) and AMI (29.7% vs. 21.8%, P<0.01) cohorts. In a multivariable logistic regression model, the multivariable adjusted odds ratio for WRF was 1.90 [95% confidence interval (CI) 1.25-2.88; P = 0.003] and 1.56 (95% CI 1.13-2.16; P = 0.002) in the ADHF and AMI cohorts, respectively. The mortality risk associated with hyponatraemia was attenuated in the absence of WRF.

CONCLUSION

Hyponatraemia predicts the development of WRF in two clinical scenarios that frequently lead to the type I CRS. These data are consistent with the concept that congestion and neurohormonal activation play a pivotal role in the pathophysiology of acute cardio-renal failure.

Fluid loss, venous congestion, and worsening renal function in acute decompensated heart failure

AIMS

To investigate the relationship between decongestion, central venous pressure, and risk of worsening renal function (WRF) in patients with acute decompensated heart failure (ADHF).

METHODS AND RESULTS

We studied 475 patients with ADHF, of whom 238 underwent right heart catheterization. Right atrial pressure (RAP) was measured at baseline and at 24 h. Net fluid loss was recorded in the first 24 h. WRF was defined as a >0.3 mg/dL increase in serum creatinine above baseline. WRF occurred in 84 catheterized patients (35.3%). There was a weak correlation between baseline RAP and baseline estimated glomerular filtration rate (r = -0.17, P = 0.009). The amount of fluid removed during the first 24 h did not correlate with the magnitude of RAP reduction (r = 0.06, P = 0.35). No association was observed between WRF and baseline RAP [odds ratio (OR) 1.06, 95% confidence interval (CI) 0.80-1.41, P = 0.68 per 6.6 mmHg] or the decrease in RAP (adjusted OR 1.13, 95% CI 0.85-1.49, P = 0.40 per 5.3 mmHg reduction in RAP). In contrast, smaller net fluid loss was strongly associated with increased WRF risk. Compared with the first net fluid loss tertile, the adjusted OR was 1.85 (95% CI 0.90-3.80, P = 0.10) and 2.58 (95% CI 1.27-5.25; P = 0.009) for the second and third tertile, respectively (P for trend <0.0001).

CONCLUSION

Smaller early net fluid loss is associated with increased risk for WRF. RAP is not a reliable surrogate of the magnitude of decongestion and risk of WRF. Future research is necessary to determine if targeting congestion may help prevent WRF.