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

Pathophysiology of acute heart failure: a world to know

Our understanding of the pathophysiological mechanisms of heart failure (HF) has changed considerably in recent years, progressing from a merely haemodynamic viewpoint to a concept of systemic and multifactorial involvement in which numerous mechanisms interact and concatenate. The effects of these mechanisms go beyond the heart itself, to other organs of vital importance such as the kidneys, liver and lungs. Despite this, the pathophysiology of acute HF still has aspects that elude our deeper understanding. Haemodynamic overload, venous congestion, neurohormonal systems, natriuretic peptides, inflammation, oxidative stress and its repercussion on cardiac and vascular remodelling are currently considered the main players in acute HF. Starting with the concept of acute HF, this review provides updates on the various mechanisms involved in this disease.

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.

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.

Effect of estimated plasma volume reduction on renal function for acute heart failure differs between patients with preserved and reduced ejection fraction

BACKGROUND

The prognostic relevance of plasma volume reduction (PVR) in acute heart failure patients remains unclear because of the confounding hemodynamic effect of left ventricular ejection fraction impairment on kidney function.

METHODS AND RESULTS

Subjects enrolled in the West Tokyo Heart Failure Registry were examined. The PV at admission and discharge was estimated from the subjects' body weight and its deviation from the ideal body weight. Patients in the top tertile of estimated PVR were classified as PVR+. Of the 381 patients with acute heart failure, 181 (47.5%) had heart failure with preserved ejection fraction (HFpEF). Estimated PVR was associated with worsening renal function in the HFpEF (odds ratio, 3.28; 95% confidence interval, 1.55-6.96; P=0.002) but not in the heart failure with reduced ejection fraction cohort (odds ratio, 1.22; 95% confidence interval, 0.61-2.42; P=0.57). This association in the HFpEF cohort remained significant after adjusting for a history of hypertension and diabetes mellitus and the estimated glomerular filtration rate (odds ratio, 3.34; 95% confidence interval, 1.52-7.33; P=0.003). The use of intravenous diuretics was a significant predictor of PVR in the HFpEF and heart failure with reduced ejection fraction groups.

CONCLUSIONS

The effect of estimated PVR differs by HF type, and the estimated PVR during hospitalization is a predictor of worsening renal function in patients with HFpEF but not in heart failure with reduced ejection fraction.

CLINICAL TRIAL REGISTRATION

URL: http://www.umin.ac.jp/ctr/index-j.html. Unique identifier: UMIN000001549.

Novel markers and therapies for patients with acute heart failure and renal dysfunction

BACKGROUND

Acute kidney injury complicates decompensated heart failure in ∼33% of cases and is associated with morbidity and mortality; thus, we sought to systematically review this topic in order to summarize novel diagnostic and therapeutic approaches.

METHODS

Structured PubMed searches on these topics were conducted in February 2014 and relevant literature was identified. The PubMed search identified a total of 192 articles that were individually screened for inclusion in this analysis, and 58 were included.

RESULTS

Acute kidney injury, defined by substantial increases in serum creatinine, is associated consistently with prolonged length of stay, rehospitalization, and mortality. Biomarker studies suggested that natriuretic peptides are prognostic for shorter- and longer-term mortality. Novel proteins indicating kidney damage and albumin in the urine are associated with acute kidney injury. The most promising acute pharmacologic treatment appears to be serelaxin, which has been shown to improve acute heart failure symptoms, hemodynamic parameters, and renal function.

CONCLUSIONS

The presence of acute kidney injury results in worse clinical outcomes for patients with acute heart failure. Novel biomarkers and therapies hold the promise of improving both cardiac and renal outcomes in these patients.

Cardiorenal interactions in acute decompensated heart failure: contemporary concepts facing emerging controversies

Simultaneous dysfunction of the heart and the kidney represents a distinct spectrum of disease states composed of complex clinical scenarios with adverse outcomes. Worsening renal function (WRF) in the setting of acute decompensated heart failure (ADHF) is one such clinical setup for which the underlying mechanisms are poorly understood. Apparent discrepancies exist between the emerging data on the cardiorenal interactions of patients with ADHF and contemporary concepts such as the low forward flow or the high backward pressure hypotheses. The findings of recent retrospective studies also suggest that apparent "improvement in renal function" might be yet another risk factor for untoward outcomes in this patient population, further challenging our current understanding of the cardiorenal interactions. Besides, these data do not seem to fully support our conventional thinking about other aspects of these interactions such as the independent adverse impact of WRF on the outcomes of patients with ADHF, pointing to congestion as a possibly overlooked factor. In this article, we provide an overview of these emerging controversial issues with the goal of identifying the areas where clinical research could be most helpful, because it is of paramount importance to characterize the pathways leading to WRF in ADHF to develop a mechanistically relevant management strategy. Although the paucity of data coupled with the complexity of this field precludes any firm conclusion, these discussions are meant to prompt clinicians and researchers to revisit a number of long-believed concepts surrounding the cardiorenal interactions in ADHF.

A patient with heart failure and worsening kidney function

There is high prevalence of CKD, defined by reduced GFR, in patients with heart failure. Reduced kidney function is associated with increased morbidity and mortality in this patient population. The cardiorenal syndrome (CRS) involves a bidirectional relationship between the heart and kidneys whereby dysfunction in either may exacerbate the function of the other, but this syndrome has been difficult to precisely define because it has many complex physiologic, biochemical, and hormonal abnormalities. The pathophysiology of CRS is not completely understood, but potential mechanisms include reduced kidney perfusion due to decreased forward flow, increased right ventricular and venous pressure, and neurohormonal adaptations. Treatment options include inotropic medications; diuretics; ultrafiltration; and medications, such as β-blockers, inhibitors of the renin-angiotensin-aldosterone system, and more novel treatments that focus on unique aspects of the pathophysiology. Recent observational studies suggest that treatments that result in a decrease in venous pressure and lead to hemoconcentration may be associated with improved outcomes. Patients with CRS that is not responsive to medical interventions should be considered for ventricular assist devices, heart transplantation, or combined heart and kidney transplantation.

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.

Haemoconcentration, renal function, and post-discharge outcomes among patients hospitalized for heart failure with reduced ejection fraction: insights from the EVEREST trial

AIMS

Haemoconcentration has been studied as a marker of decongestion in patients with hospitalization for heart failure (HHF). We describe the relationship between haemoconcentration, worsening renal function, post-discharge outcomes, and clinical and laboratory markers of congestion in a large multinational cohort of patients with HHF.

METHODS AND RESULTS

In 1684 patients with HHF with ejection fraction (EF) ≤40% assigned to the placebo arm of the Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study with Tolvaptan (EVEREST) trial, absolute in-hospital haematocrit change was calculated as the change between baseline and discharge or day 7 (whichever occurred first). Patient characteristics, changes in renal function, and outcomes over a median follow-up of 9.9 months were compared by in-hospital haematocrit change. Overall, 26% of patients had evidence of haemoconcentration (i.e., ≥3% absolute increase in haematocrit). Patients with greater increases in haematocrit tended to have better baseline renal function. Haemoconcentration correlated with greater risk of in-hospital worsening renal function, but renal parameters generally returned to baseline within 4 weeks post-discharge. Patients with haemoconcentration were less likely to have clinical congestion at discharge, and experienced greater in-hospital decreases in body weight and natriuretic peptide levels. After adjustment for baseline clinical risk factors, every 5% increase of in-hospital haematocrit change was associated with a decreased risk of all-cause death [hazard ratio (HR) 0.81, 95% confidence interval (CI) 0.70-0.95]. Haematocrit change was also associated with decreased cardiovascular mortality or heart failure (HF) hospitalization at ≤100 days post-randomization (HR 0.73, 95% CI 0.71-0.76).

CONCLUSION

In this large cohort of patients with HHF with reduced EF, haemoconcentration was associated with greater improvements in congestion and decreased mortality and HF re-hospitalization despite an increased risk of in-hospital worsening renal function.