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Congestion is the primary pathophysiological lesion in most heart failure (HF) hospitalizations. Renal congestion increases renal tubular pressure, reducing glomerular filtration rate (GFR) and diuresis. Because each nephron is a fluid-filled column, renal negative pressure therapy (rNPT) applied to the urinary collecting system should reduce tubular pressure, potentially improving kidney function. We evaluated the renal response to rNPT in congestive HF. Ten anesthetized ∼80-kg pigs underwent instrumentation with bilateral renal pelvic JuxtaFlow catheters. GFR was determined by iothalamate clearance (mGFR) and renal plasma flow (RPF) by para-aminohippurate clearance. Each animal served as its own control with randomization of left versus right kidney to -30 mmHg rNPT or no rNPT. mGFR and RPF were measured simultaneously from the rNPT and no rNPT kidney. Congestive HF was induced via cardiac tamponade maintaining central venous pressure at 20-22.5 mmHg throughout the experiment. Before HF induction, rNPT increased natriuresis, diuresis, and mGFR compared with the control kidney ( P < 0.001 for all). Natriuresis, diuresis, and mGFR decreased following HF ( P < 0.001 for all) but were higher in rNPT kidney versus control ( P < 0.001 for all). RPF decreased during HF ( P < 0.001) without significant differences between rNPT treatments. During HF, the rNPT kidney had similar diuresis and natriuresis ( P > 0.5 for both) and higher fractional excretion of sodium ( P = 0.001) compared with the non-rNPT kidney in the no HF period. In conclusion, rNPT resulted in significantly increased diuresis, natriuresis, and mGFR, with or without experimental HF. rNPT improved key renal parameters of the congested cardiorenal phenotype.

Heart failure is characterized by pathologic hemodynamic derangements, including elevated cardiac filling pressures ("backward" failure), which may or may not coexist with reduced cardiac output ("forward" failure). Even when normal during unstressed conditions such as rest, hemodynamics classically become abnormal during stressors such as exercise in patients with heart failure. This has important upstream and downstream effects on multiple organ systems, particularly with respect to the lungs and kidneys. Hemodynamic abnormalities in heart failure are affected by processes that extend well beyond the cardiac myocyte, including important roles for pericardial constraint, ventricular interaction, and altered venous capacity. Hemodynamic perturbations have widespread effects across multiple heart failure phenotypes, ranging from reduced to preserved ejection fraction, acute to chronic disease, and cardiogenic shock to preserved perfusion states. In the lung, hemodynamic derangements lead to the development of abnormalities in ventilatory control and efficiency, pulmonary congestion, capillary stress failure, and eventually pulmonary vascular disease. In the kidney, hemodynamic perturbations lead to sodium and water retention and worsening renal function. Improved understanding of the mechanisms by which altered hemodynamics in heart failure affect the lungs and kidneys is needed in order to design novel strategies to improve clinical outcomes.

Objectives: This study aimed to examine whether incorporation of a comprehensive set of measures of decongestion modifies the association of acute declines in kidney function with outcomes., Background: In-hospital acute declines in kidney function occur in approximately 20% to 30% of patients admitted with acute decompensated heart failure (ADHF) and may be associated with adverse outcomes., Methods: Using data from EVEREST (Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study With Tolvaptan), we used multivariable Cox regression models to evaluate the association between in-hospital changes in estimated glomerular filtration rate (eGFR) with death and a composite outcome of cardiovascular death and hospitalization for heart failure. We evaluated eGFR declines within the context of changes in markers of volume overload including b-type natriuretic peptide (BNP), N-terminal prohormone of B-type natriuretic peptide (NT-proBNP), and weight, as well as changes in measures of hemoconcentration including hematocrit, albumin, and total protein., Results: Among 3,715 patients over a median follow-up of 9.9 months, every 30% decline in eGFR was associated with higher risk of both death (hazard ratio [HR]: 1.19; 95% confidence interval [CI]: 1.07 to 1.31) and the composite outcome (HR: 1.09; 95% CI: 1.01 to 1.18) in adjusted models. The acute decline in eGFR was no longer associated with higher risk of either outcome as long as there was evidence of decongestion, either by declines in BNP, NT-proBNP, or weight or by increases in hematocrit, albumin or total protein. Interaction testing between decline in eGFR and changes in hematocrit, albumin, and total protein was statistically significant (p interaction of <0.01 for death and p interaction of ≤0.01 for composite for all 3 biomarkers). Interaction between change in eGFR and changes in BNP (p interaction = 0.07 for death; p interaction = 0.08 for composite), NT-proBNP (p interaction = 0.15 for death; p interaction = 0.18 for composite) and weight (p interaction = 0.13 for death; p interaction = 0.19 for composite) did not meet statistical significance., Conclusions: Overall, acute declines in eGFR are associated with adverse outcomes, with evidence of modification by changes in markers of decongestion, suggesting that they are no longer associated with adverse outcomes if these markers are concomitantly improving., (Copyright © 2020 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Patients with heart failure (HF) with preserved ejection fraction (HFpEF) and obesity display a number of pathophysiologic features that may render them more or less vulnerable to negative effects of decongestion on renal function, including greater right ventricular remodeling, plasma volume expansion and pericardial restraint. We aimed to contrast the renal response to decongestion in obese compared to nonobese patients with HFpEF METHODS AND RESULTS: National Institutes of Health heart failure network studies that enrolled patients with acute decompensated HFpEF (EF ≥ 50%) were included (DOSE, CARRESS, ROSE, and ATHENA). Obese HFpEF was defined as a body mass index ≥ 30 kg/m 2 . Compared to nonobese HFpEF (n = 118), patients with obese HFpEF (n = 214) were an average of 9 years younger (71 vs 80 years,< 0.001), were more likely to have diabetes (64% vs 31%, P< 0.001) but had less atrial fibrillation (56% vs 75%, P< 0.001). Renal dysfunction (glomerular filtration rate < 60 mL/min/1.73m 2 ) was present in 82% of patients, and there was no difference at baseline between obese and nonobese patients. Despite similar weight loss through decongestive therapies, obese patients with HFpEF demonstrated greater rise in creatinine (Cr) and decline in glomerular filtration rate, with a 2-fold higher incidence of mild worsening renal function (rise in Cr ≥ 0.3 mg/dL) (28 vs 14%, P = 0.008) and a substantially greater increase in severe worsening of renal function (rise in Cr > 0.5 mg/dL) (9 vs 0%, P = 0.002)., Conclusions: Despite being nearly a decade younger, obese patients with HFpEF experience greater deterioration in renal function during decongestion than do nonobese patients with HFpEF. Further study to elucidate the complex relationships between volume distribution, cardiorenal hemodynamics and adiposity in HFpEF is needed., (Copyright © 2019 Elsevier Inc. All rights reserved.)

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.

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., (© 2018 American Heart Association, Inc.)

Background: Recent epidemiological studies have implicated chloride, rather than sodium, as the driver of poor survival previously attributed to hyponatremia in heart failure. Accumulating basic science evidence has identified chloride as a critical factor in renal salt sensing. Our goal was to probe the physiology bridging this basic and epidemiological literature., Methods and Results: Two heart failure cohorts were included: (1) observational: patients receiving loop diuretics at the Yale Transitional Care Center (N=162) and (2) interventional pilot: stable outpatients receiving ≥80 mg furosemide equivalents were studied before and after 3 days of 115 mmol/d supplemental lysine chloride (N=10). At the Yale Transitional Care Center, 31.5% of patients had hypochloremia (chloride ≤96 mmol/L). Plasma renin concentration correlated with serum chloride (r=-0.46; P<0.001) with no incremental contribution from serum sodium (P=0.49). Hypochloremic versus nonhypochloremic patients exhibited renal wasting of chloride (P=0.04) and of chloride relative to sodium (P=0.01), despite better renal free water excretion (urine osmolality 343±101 mOsm/kg versus 475±136; P<0.001). Hypochloremia was associated with poor diuretic response (odds ratio, 7.3; 95% confidence interval, 3.3-16.1; P<0.001). In the interventional pilot, lysine chloride supplementation was associated with an increase in serum chloride levels of 2.2±2.3 mmol/L, and the majority of participants experienced findings such as hemoconcentration, weight loss, reduction in amino terminal, pro B-type natriuretic peptide, increased plasma renin activity, and increased blood urea nitrogen to creatinine ratio., Conclusions: Hypochloremia is associated with neurohormonal activation and diuretic resistance with chloride depletion as a candidate mechanism. Sodium-free chloride supplementation was associated with increases in serum chloride and changes in several cardiorenal parameters., Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02031354., (© 2016 American Heart Association, Inc.)

Background: Reduction in systolic blood pressure (SBP reduction) during the treatment of acute decompensated heart failure is strongly and independently associated with worsening renal function. Our objective was to determine whether SBP reduction or titration of oral neurohormonal antagonists during acute decompensated heart failure treatment negatively influences diuresis and decongestion., Methods and Results: SBP reduction was evaluated from admission to discharge in consecutive acute decompensated heart failure admissions (n=656). Diuresis and decongestion were examined across a range of parameters, such as diuretic efficiency, fluid output, hemoconcentration, and diuretic dose. The average reduction in SBP was 14.4 ± 19.4 mm Hg, and 77.6% of the population had discharge SBP lower than admission. SBP reduction was strongly associated with worsening renal function (odds ratio, 1.9; 95% confidence interval, 1.2-2.9; P=0.004), a finding that persisted after adjusting for parameters of diuresis and decongestion (odds ratio, 2.0; 95% confidence interval, 1.3-3.2; P=0.002). However, SBP reduction did not negatively affect diuresis or decongestion (P ≥ 0.25 for all parameters). Uptitration of neurohormonal antagonists occurred in >50% of admissions and was associated with a modest additional reduction in blood pressure (≤ 5.6 mm Hg). Notably, worsening renal function was not increased, and diuretic efficiency was significantly improved with the uptitration of neurohormonal antagonists., Conclusions: Despite a higher rate of worsening renal function, blood pressure reduction was not associated with worsening of diuresis or decongestion. Furthermore, titration of oral neurohormonal antagonists was actually associated with improved diuresis in this cohort. These results provide reassurance that the guideline-recommended titration of chronic oral medication during acute decompensated heart failure hospitalization may not be antagonistic to the short-term goal of decongestion., (© 2015 American Heart Association, Inc.)

Background: The long-term durability and prognostic significance of improvement in renal function after mechanical circulatory support (MCS) has yet to be characterized in a large multicenter population. The primary goals of this analysis were to describe serial post-MCS changes in estimated glomerular filtration rate (eGFR) and determine their association with all-cause mortality., Methods and Results: Adult patients enrolled in the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) with serial creatinine levels available (n=3363) were studied. Early post-MCS, eGFR improved substantially (median improvement, 48.9%; P<0.001) with 22.3% of the population improving their eGFR by ≥100% within the first few weeks. However, in the majority of patients, this improvement was transient, and by 1 year, eGFR was only 6.7% above the pre-MCS value (P<0.001). This pattern of early improvement followed by deterioration in eGFR was observed with both pulsatile and continuous-flow devices. Interestingly, poor survival was associated with both marked improvement (adjusted hazard ratio [HR], 1.64; 95% confidence interval [CI], 1.19-2.26; P=0.002) and worsening in eGFR (adjusted HR, 1.63; 95% CI, 1.15-2.13; P=0.004)., Conclusions: Post-MCS, early improvement in renal function is common but seems to be largely transient and not necessarily indicative of an improved prognosis. This pattern was observed with both pulsatile and continuous-flow devices. Additional research is necessary to better understand the mechanistic basis for these complex post-MCS changes in renal function and their associated survival disadvantage., Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00119834.

Background: Identifying reversible renal dysfunction (RD) in the setting of heart failure is challenging. The goal of this study was to evaluate whether elevated admission blood urea nitrogen/creatinine ratio (BUN/Cr) could identify decompensated heart failure patients likely to experience improvement in renal function (IRF) with treatment., Methods and Results: Consecutive hospitalizations with a discharge diagnosis of heart failure were reviewed. IRF was defined as ≥20% increase and worsening renal function as ≥20% decrease in estimated glomerular filtration rate. IRF occurred in 31% of the 896 patients meeting eligibility criteria. Higher admission BUN/Cr was associated with in-hospital IRF (odds ratio, 1.5 per 10 increase; 95% confidence interval [CI], 1.3-1.8; P<0.001), an association persisting after adjustment for baseline characteristics (odds ratio, 1.4; 95% CI, 1.1-1.8; P=0.004). However, higher admission BUN/Cr was also associated with post-discharge worsening renal function (odds ratio, 1.4; 95% CI, 1.1-1.8; P=0.011). Notably, in patients with an elevated admission BUN/Cr, the risk of death associated with RD (estimated glomerular filtration rate <45) was substantial (hazard ratio, 2.2; 95% CI, 1.6-3.1; P<0.001). However, in patients with a normal admission BUN/Cr, RD was not associated with increased mortality (hazard ratio, 1.2; 95% CI, 0.67-2.0; P=0.59; p interaction=0.03)., Conclusions: An elevated admission BUN/Cr identifies decompensated patients with heart failure likely to experience IRF with treatment, providing proof of concept that reversible RD may be a discernible entity. However, this improvement seems to be largely transient, and RD, in the setting of an elevated BUN/Cr, remains strongly associated with death. Further research is warranted to develop strategies for the optimal detection and treatment of these high-risk patients.

Background: In the setting of acute decompensated heart failure, worsening renal function (WRF) and improved renal function (IRF) have been associated with similar hemodynamic derangements and poor prognosis. Our aim was to further characterize IRF and its associated mortality risk., Methods and Results: Consecutive patients with a discharge diagnosis of congestive heart failure at the Hospital of the University of Pennsylvania were reviewed. IRF was defined as a ≥20% improvement and WRF as a ≥20% deterioration in glomerular filtration rate. Overall, 903 patients met the eligibility criteria, with 31.4% experiencing IRF. Baseline venous congestion/right-side cardiac dysfunction was more common (P ≤ .04) and volume of diuresis (P = .003) was greater in patients with IRF. IRF was associated with a greater incidence of preadmission (odds ratio [OR] 4.2, 95% confidence interval [CI] 2.6-6.7; P < .0001) and postdischarge (OR 1.8, 95% CI 1.2-2.7; P = .006) WRF. IRF was associated with increased mortality (adjusted hazard ratio 1.3, 95% CI, 1.1-1.7; P = .011), a finding largely restricted to patients with postdischarge recurrence of renal dysfunction (P interaction = .038)., Conclusions: IRF is associated with significantly worsened survival and may represent the resolution of venous congestion-induced preadmission WRF. Unlike WRF, the renal dysfunction in IRF patients occurs independently from the confounding effects of acute decongestion and may provide incremental information for the study of cardiorenal interactions., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Background: Worsening renal function (WRF) in the setting of heart failure has been associated with increased mortality. However, it is unclear if this decreased survival is a direct result of the reduction in glomerular filtration rate (GFR) or if the mechanism underlying the deterioration in GFR is driving prognosis. Given that WRF in the setting of angiotensin-converting enzyme inhibitor (ACE-I) initiation is likely mechanistically distinct from spontaneously occurring WRF, we investigated the relative early WRF-associated mortality rates in subjects randomized to ACE-I or placebo., Methods and Results: Subjects in the Studies Of Left Ventricular Dysfunction (SOLVD) limited data set (n=6337) were studied. The interaction between early WRF (decrease in estimated GFR ≥20% at 14 days), randomization to enalapril, and mortality was the primary end point. In the overall population, early WRF was associated with increased mortality (adjusted hazard ratio [HR], 1.2; 95% CI, 1.0-1.4; P=0.037). When analysis was restricted to the placebo group, this association strengthened (adjusted HR, 1.4; 95% CI, 1.1-1.8; P=0.004). However, in the enalapril group, early WRF had no adverse prognostic significance (adjusted HR, 1.0; 95% CI, 0.8-1.3; P=1.0; P=0.09 for the interaction). In patients who continued to receive study drug despite early WRF, a survival advantage remained with enalapril therapy (adjusted HR, 0.66; 95% CI, 0.5-0.9; P=0.018)., Conclusions: These data support the notion that the mechanism underlying WRF is important in determining its prognostic significance. Specifically, early WRF in the setting of ACE-I initiation appears to represent a benign event that is not associated with a loss of benefit from continued ACE-I therapy.

Aims: One of the primary determinants of blood flow in regional vascular beds is perfusion pressure. Our aim was to investigate if reduction in blood pressure during the treatment of decompensated heart failure would be associated with worsening renal function (WRF). Our secondary aim was to evaluate the prognostic significance of this potentially treatment-induced form of WRF., Methods and Results: Subjects included in the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) trial limited data were studied (386 patients). Reduction in systolic blood pressure (SBP) was greater in patients experiencing WRF (-10.3 ± 18.5 vs. -2.8 ± 16.0 mmHg, P < 0.001) with larger reductions associated with greater odds for WRF (odds ratio = 1.3 per 10 mmHg reduction, P < 0.001). Systolic blood pressure reduction (relative change > median) was associated with greater doses of in-hospital oral vasodilators (P ≤ 0.017), thiazide diuretic use (P = 0.035), and greater weight reduction (P = 0.023). In patients with SBP-reduction, WRF was not associated with worsened survival [adjusted hazard ratio (HR) = 0.76, P = 0.58]. However, in patients without SBP-reduction, WRF was strongly associated with increased mortality (adjusted HR = 5.3, P < 0.001, P interaction = 0.001)., Conclusion: During the treatment of decompensated heart failure, significant blood pressure reduction is strongly associated with WRF. However, WRF that occurs in the setting of SBP-reduction is not associated with an adverse prognosis, whereas WRF in the absence of this provocation is strongly associated with increased mortality. These data suggest that WRF may represent the final common pathway of several mechanistically distinct processes, each with potentially different prognostic implications.

Background: Overly aggressive diuresis leading to intravascular volume depletion has been proposed as a cause for worsening renal function during the treatment of decompensated heart failure. If diuresis occurs at a rate greater than extravascular fluid can refill the intravascular space, the concentration of such intravascular substances as hemoglobin and plasma proteins increases. We hypothesized that hemoconcentration would be associated with worsening renal function and possibly would provide insight into the relationship between aggressive decongestion and outcomes., Methods and Results: Subjects in the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness trial limited data set with a baseline/discharge pair of hematocrit, albumin, or total protein values were included (336 patients). Baseline-to-discharge increases in these parameters were evaluated, and patients with >or=2 in the top tertile were considered to have evidence of hemoconcentration. The group experiencing hemoconcentration received higher doses of loop diuretics, lost more weight/fluid, and had greater reductions in filling pressures (P<0.05 for all). Hemoconcentration was strongly associated with worsening renal function (odds ratio, 5.3; P<0.001), whereas changes in right atrial pressure (P=0.36) and pulmonary capillary wedge pressure (P=0.53) were not. Patients with hemoconcentration had significantly lower 180-day mortality (hazard ratio, 0.31; P=0.013). This relationship persisted after adjustment for baseline characteristics (hazard ratio, 0.16; P=0.001)., Conclusions: Hemoconcentration is significantly associated with measures of aggressive fluid removal and deterioration in renal function. Despite this relationship, hemoconcentration is associated with substantially improved survival. These observations raise the question of whether aggressive decongestion, even in the setting of worsening renal function, can positively affect survival.

Objectives: Worsening renal function (WRF) during the treatment of decompensated heart failure, frequently defined as an absolute increase in serum creatinine >or=0.3 mg/dl, has been reported as a strong adverse prognostic factor in several studies. We hypothesized that this definition of WRF is biased by baseline renal function secondary to the exponential relationship between creatinine and renal function., Methods: We reviewed consecutive admissions with a discharge diagnosis of heart failure. An increase in creatinine >or=0.3 mg/dl (WRF(CREAT)) was compared to a decrease in GFR >or=20% (WRF(GFR))., Results: Overall, 993 admissions met eligibility. WRF(CREAT) occurred in 31.5% and WRF(GFR) in 32.7%. WRF(CREAT) and WRF(GFR) had opposing relationships with baseline renal function (OR = 1.9 vs. OR = 0.51, respectively, p < 0.001). Both definitions had similar unadjusted associations with death at 30 days [WRF(GFR) OR = 2.3 (95% CI 1.1-4.8), p = 0.026; WRF(CREAT) OR = 2.1 (95% CI 1.0-4.4), p = 0.047]. Controlling for baseline renal insufficiency, WRF(GFR) added incrementally in the prediction of mortality (p = 0.009); however, WRF(CREAT) did not (p = 0.11)., Conclusions: WRF, defined as an absolute change in serum creatinine, is heavily biased by baseline renal function. An alternative definition of WRF should be considered for future studies of cardio-renal interactions., (Copyright 2010 S. Karger AG, Basel.)

Objectives: The purpose of this study was to investigate whether a surrogate for renal neurohormonal activation, blood urea nitrogen (BUN), could identify patients destined to experience adverse outcomes associated with the use of high-dose loop diuretics (HDLD). Background: Loop diuretics are commonly used to control congestive symptoms in heart failure; however, these agents cause neurohormonal activation and have been associated with worsened survival. Methods: Subjects in the BEST (Beta-Blocker Evaluation of Survival Trial) receiving loop diuretics at baseline were analyzed (N = 2,456). The primary outcome was the interaction between BUN- and HDLD-associated mortality. Results: In the overall cohort, HDLD use (≥160 mg/day) was associated with increased mortality (hazard ratio [HR]: 1.56; 95% confidence interval [CI]: 1.35 to 1.80). However, after extensively controlling for baseline characteristics, this association did not persist (HR: 1.06; 95% CI: 0.89 to 1.25). In subjects with BUN levels above the median (21.0 mg/dl), both the unadjusted (HR: 1.59; 95% CI: 1.34 to 1.88) and adjusted (HR: 1.29; 95% CI: 1.07 to 1.60) risk of death was higher in the HDLD group. In patients with BUN levels below the median, there was no associated risk with HDLD (HR: 0.99; 95% CI: 0.75 to 1.34) and after controlling for baseline characteristics, the HDLD group had significantly improved survival (HR: 0.71; 95% CI: 0.49 to 0.96) (p interaction = 0.018). Conclusions: The risk associated with HDLD use is strongly dependent on BUN concentrations with reduced survival in patients with an elevated BUN level and improved survival in patients with a normal BUN level. These data suggest a role for neurohormonal activation in loop diuretic–associated mortality. [Copyright &y& Elsevier]