Cardiorenal Syndrome: Pathophysiology

Cardiorenal syndrome commonly refers to the collective dysfunction of heart and kidney resulting in a cascade of feedback mechanism causing damage to both the organs and is associated with adverse clinical outcomes. The pathophysiology of cardiorenal syndrome is complex, multifactorial, and dynamic. Improving the understanding of disease mechanisms will aid in developing targeted pharmacologic and nonpharmacologic therapies for the management of this syndrome. This article discusses the various mechanisms involved in the pathophysiology of the cardiorenal syndrome.

Neutrophil Gelatinase-Associated Lipocalin for Acute Kidney Injury During Acute Heart Failure Hospitalizations: The AKINESIS Study

BACKGROUND

Worsening renal function (WRF) often occurs during acute heart failure (AHF) and can portend adverse outcomes; therefore, early identification may help mitigate risk. Neutrophil gelatinase-associated lipocalin (NGAL) is a novel renal biomarker that may predict WRF in certain disorders, but its value in AHF is unknown.

OBJECTIVES

This study sought to determine whether NGAL is superior to creatinine for prediction and/or prognosis of WRF in hospitalized patients with AHF treated with intravenous diuretic agents.

METHODS

This was a multicenter, prospective cohort study enrolling patients presenting with AHF requiring intravenous diuretic agents. The primary outcome was whether plasma NGAL could predict the development of WRF, defined as a sustained increase in plasma creatinine of 0.5 mg/dl or ≥50% above first value or initiation of acute renal-replacement therapy, within the first 5 days of hospitalization. The main secondary outcome was in-hospital adverse events.

RESULTS

We enrolled 927 subjects (mean age, 68.5 years; 62% men). The primary outcome occurred in 72 subjects (7.8%). Peak NGAL was more predictive than the first NGAL, but neither added significant diagnostic utility over the first creatinine (areas under the curve: 0.656, 0.647, and 0.652, respectively). There were 235 adverse events in 144 subjects. The first NGAL was a better predictor than peak NGAL, but similar to the first creatinine (areas under the curve: 0.691, 0.653, and 0.686, respectively). In a post hoc analysis of subjects with an estimated glomerular filtration rate <60 ml/min/1.73 m(2), a first NGAL <150 ng/ml indicated a low likelihood of adverse events.

CONCLUSIONS

Plasma NGAL was not superior to creatinine for the prediction of WRF or adverse in-hospital outcomes. The use of plasma NGAL to diagnose acute kidney injury in AHF cannot be recommended at this time. (Acute Kidney Injury Neutrophil Gelatinase-Associated Lipocalin [N-GAL] Evaluation of Symptomatic Heart Failure Study [AKINESIS]; NCT01291836).

Natriuretic Peptides in Heart Failure: Atrial and B-type Natriuretic Peptides

The natriuretic peptides play a vital role in normal physiology and as counter-regulatory hormones in heart failure (HF). Clinical assessment of their levels (for B-type natriuretic peptide [BNP], N-terminal proBNP, and the midregion of N-terminal pro-atrial natriuretic peptide) have become valuable tools in diagnosing patients with HF as well as risk stratifying and guiding therapy. Their roles have further expanded beyond HF to other cardiovascular conditions and for risk stratification in asymptomatic individuals. Understanding the clinical use of these hormones is vital to achieving their full potential.

Role of Cardiac Troponin Levels in Acute Heart Failure

Cardiac troponin (cTn) is the primary biomarker for the diagnosis of myocardial necrosis in an acute coronary syndrome (ACS). cTn levels can also be elevated in many other conditions, including heart failure, with significant prognostic value. An elevated cTn level can be found in both acute and chronic heart failure and its presence is believed to be due to multiple different pathophysiological processes. In acute decompensated heart failure (AHF), an elevated cTn level has been repeatedly shown to correlate with increased short- and long-term mortality and, to a lesser extent, readmission rates. These associations have been demonstrated with both I and T isoforms of cTn, as well as when troponin is measured with conventional assays or new high-sense assays. In multimarker models, cTn has repeatedly been found to be an independent predictive variable enhancing prognostic ability of the model. cTn is therefore an important biomarker for prognosis in AHF.

Biomarkers for Heart Failure: An Update for Practitioners of Internal Medicine

Biomarkers have become an integral part of practicing medicine, especially in heart failure. The natriuretic peptides are commonly used in the evaluation of heart failure, but their role extends beyond diagnosis and includes risk stratification and management of heart failure patients. Newer biomarkers have arrived and are becoming part of routine care of heart failure patients. Both ST2 and high-sensitivity troponin have significant prognostic value for mortality, but also may assist in the titration of medical therapy. Procalcitonin can help guide appropriate antibiotic use in patients with heart failure. The ability to appropriately use and interpret these biomarkers is imperative to the care of heart failure patients, especially as these newer biomarkers become widely used.

B-type natriuretic peptide trend predicts clinical significance of worsening renal function in acute heart failure

AIMS

In acute heart failure (AHF), relationships between changes in B-type natriuretic peptide (BNP) and worsening renal function (WRF) and its prognostic implications have not been fully determined. We investigated the relationship between WRF and a decrease in BNP with in-hospital and 1-year mortality in AHF.

METHODS AND RESULTS

The Acute Kidney Injury NGAL Evaluation of Symptomatic heart faIlure Study (AKINESIS) was a prospective, international, multicentre study of AHF patients. Severe WRF (sWRF) was a sustained increase of ≥44.2 μmol/L (0.5 mg/dL) or ≥50% in creatinine, non-severe WRF (nsWRF) was a non-sustained increase of ≥26.5 μmol/L (0.3 mg/dL) or ≥50% in creatinine, and WRF with clinical deterioration was nsWRF with renal replacement therapy, inotrope use, or mechanical ventilation. Decreased BNP was defined as a ≥30% reduction in the last measured BNP compared to admission BNP. Among 814 patients, the incidence of WRF was not different between patients with or without decreased BNP (nsWRF: 33% vs. 31%, P = 0.549; sWRF: 11% vs. 9%, P = 0.551; WRF with clinical deterioration: 8% vs. 10%, P = 0.425). Decreased BNP was associated with better in-hospital and 1-year mortality regardless of WRF, while WRF was associated with worse outcomes only in patients without decreased BNP. In multivariate Cox regression analysis, decreased BNP, sWRF, and WRF with clinical deterioration were significantly associated with 1-year mortality.

CONCLUSIONS

Decreased BNP was associated with better in-hospital and long-term outcomes. WRF was only associated with adverse outcomes in patients without decreased BNP.

Decongestion discriminates risk for one-year mortality in patients with improving renal function in acute heart failure

AIMS

Improving renal function (IRF) is paradoxically associated with worse outcomes in acute heart failure (AHF), but outcomes may differ based on response to decongestion. We explored if the relationship of IRF with mortality in hospitalized AHF patients differs based on successful decongestion.

METHODS AND RESULTS

We evaluated 760 AHF patients from AKINESIS for the relationship between IRF, change in B-type natriuretic peptide (BNP), and 1-year mortality. IRF was defined as a ≥20% increase in estimated glomerular filtration rate (eGFR) relative to admission. Adequate decongestion was defined as a ≥40% decrease in last measured BNP relative to admission. IRF occurred in 22% of patients who had a mean age of 69 years, 58% were men, 72% were white, and median admission eGFR was 49 mL/min/1.73 m2 . IRF patients had more severe heart failure reflected by lower admission eGFR, higher blood urea nitrogen, lower systolic blood pressure, lower sodium, and higher use of inotropes. IRF patients had higher 1-year mortality (25%) than non-IRF patients (15%) (P < 0.01). However, this relationship differed by BNP trajectory (P-interaction = 0.03). When stratified by BNP change, non-IRF patients and IRF patients with decreasing BNP had lower 1-year mortality than either non-IRF and IRF patients without decreasing BNP. However, in multivariate analysis, IRF was not associated with mortality [adjusted hazard ratio (HR) 1.0, 95% confidence interval (CI) 0.7-1.5] while BNP was (adjusted HR 0.5, 95% CI 0.3-0.7). When IRF was evaluated as transiently occurring or persisting at discharge, again only BNP change was significantly associated with mortality.

CONCLUSION

Improving renal function is associated with mortality in AHF but not independent of other variables and congestion status. Achieving adequate decongestion, as reflected by lower BNP, in AHF is more strongly associated with mortality than IRF.

Short-term prognostic implications of serum and urine neutrophil gelatinase-associated lipocalin in acute heart failure: findings from the AKINESIS study

AIMS

Kidney impairment has been associated with worse outcomes in acute heart failure (AHF), although recent studies challenge this association. Neutrophil gelatinase-associated lipocalin (NGAL) is a novel biomarker of kidney tubular injury. Its prognostic role in AHF has not been evaluated in large cohorts. The present study aimed to determine if serum NGAL (sNGAL) or urine NGAL (uNGAL) is superior to creatinine for predicting short-term outcomes in AHF.

METHODS AND RESULTS

The study was conducted in an international, multicentre, prospective cohort consisting of 927 patients with AHF. Admission and peak values of sNGAL, uNGAL and uNGAL/urine creatinine (uCr) ratio were compared to admission and peak serum creatinine (sCr). The composite endpoints were death, initiation of renal replacement therapy, heart failure (HF) readmission and any emergent HF-related outpatient visit within 30 and 60 days, respectively. The mean age of the cohort was 69 years and 62% were male. The median length of stay was 6 days. The composite endpoint occurred in 106 patients and 154 patients within 30 and 60 days, respectively. Serum NGAL was more predictive than uNGAL and the uNGAL/uCr ratio but was not superior to sCr [area under the curve: admission sNGAL 0.61, 95% confidence interval (CI) 0.55-0.67, and 0.59, 95% CI 0.54-0.65; peak sNGAL: 0.60, 95% CI 0.54-0.66, and 0.57, 95% CI 0.52-0.63; admission sCr: 0.60, 95% CI 0.54-0.64, and 0.59, 95% CI 0.53-0.64; peak sCr: 0.61, 95% CI 0.55-0.67, and 0.59, 95% CI 0.54-0.64, at 30 and 60 days, respectively]. NGAL was not predictive of the composite endpoint in multivariate analysis.

CONCLUSIONS

Serum NGAL outperformed uNGAL but neither was superior to admission or peak sCr for predicting adverse events.

Urinary Biomarkers and Kidney Outcomes: Impact of Indexing Versus Adjusting for Urinary Creatinine

RATIONALE & OBJECTIVE

Urinary biomarker concentrations are frequently indexed to urinary creatinine (Ucr) concentration in spot samples to account for urine dilution; however, this may introduce biases. We evaluated whether indexing versus adjusting urinary biomarker concentrations for Ucr concentration altered their associations with outcomes.

STUDY DESIGN

Observational cohort.

SETTING & PARTICIPANTS

We analyzed data from 2,360 Systolic Blood Pressure Intervention Trial (SPRINT) participants with estimated glomerular filtration rates < 60 mL/min/1.73 m2 and urinary albumin (UAlb) and 8 urinary kidney tubule biomarkers measured at baseline.

OUTCOMES

The primary outcome was a composite of cardiovascular disease events; secondary outcomes were all-cause mortality and a composite of kidney outcomes (50% estimated glomerular filtration rate decline, end-stage kidney disease, or transplantation).

ANALYTICAL APPROACH

We used Cox proportional hazards regression to examine the associations of 1/Ucr with outcomes and compared the associations of UAlb and 8 individual urinary tubule biomarkers with outcomes, analyzed by indexing to Ucr, adjusting for 1/Ucr or the biomarker alone (without Ucr concentration).

RESULTS

During a median follow-up of 3.3 years, 307 composite cardiovascular events, 166 deaths, and 34 composite kidney outcomes occurred. After multivariable adjustment, 1/Ucr was significantly associated with cardiovascular events (HR, 1.27 per 2-fold higher; 95% CI, 1.11-1.45), not associated with either mortality (HR, 1.06; 95% CI, 0.87-1.28) or kidney events (HR, 1.49; 95% CI, 0.95-2.35). For UAlb and urinary tubule biomarker concentrations, most risk estimates were not significantly different when indexed to Ucr concentration versus adjusted for 1/Ucr.

LIMITATIONS

Cohort excluded patients with diabetes and overall had low levels of albuminuria.

CONCLUSIONS

1/Ucr is independently associated with cardiovascular events in trial participants with chronic kidney disease. Indexing versus adjusting for 1/Ucr does not significantly change the associations of most urinary biomarkers with clinical outcomes.

Usefulness of Proneurotensin to Predict Cardiovascular and All-Cause Mortality in a United States Population (from the Reasons for Geographic and Racial Differences in Stroke Study)

Cardiovascular disease is a leading cause of death. Proneurotensin is a biomarker associated with the development of cardiovascular disease, cardiovascular mortality, and all-cause mortality. We assessed the association of fasting proneurotensin with mortal events by gender and race (black-white) in a US population. Using a case-cohort subpopulation of the Reasons for Geographic and Racial Differences in Stroke study, fasting proneurotensin was measured on a 1,046-person subcohort and in 651 participants with incident coronary heart disease. Higher proneurotensin was associated with all-cause mortality (hazard ratio [HR] 1.6 per interquartile range, 95% confidence interval [CI] 1.3 to 1.9) and cardiovascular mortality (HR 1.8, 95% CI 1.2 to 2.6). For all-cause and cardiovascular mortality, association was stronger in women (HR 1.9, 95% CI 1.4 to 2.6 and HR 2.5, 95% CI 1.4 to 4.7, respectively) than men (HR 1.4, 95% CI 1.0 to 1.8 and HR 1.4, 95% CI 0.9 to 2.3, respectively), although this difference was not significant. Proneurotensin predicted all-cause mortality in both races and was not predictive of cardiovascular mortality in whites but was in blacks. Proneurotensin was not associated with incident coronary heart disease events. Elevated proneurotensin levels predicted all-cause and cardiovascular mortality in both genders, with a trend toward stronger association in women. Associations were similar in blacks and whites. In conclusion, proneurotensin may be a useful biomarker for all-cause and cardiovascular mortality regardless of race, and it is potentially specific in women.

Relation of Decongestion and Time to Diuretics to Biomarker Changes and Outcomes in Acute Heart Failure

Prompt treatment may mitigate the adverse effects of congestion in the early phase of heart failure (HF) hospitalization, which may lead to improved outcomes. We analyzed 814 acute HF patients for the relationships between time to first intravenous loop diuretics, changes in biomarkers of congestion and multiorgan dysfunction, and 1-year composite end point of death or HF hospitalization. B-type natriuretic peptide (BNP), high sensitivity cardiac troponin I (hscTnI), urine and serum neutrophil gelatinase-associated lipocalin, and galectin 3 were measured at hospital admission, hospital day 1, 2, 3 and discharge. Time to diuretics was not correlated with the timing of decongestion defined as BNP decrease ≥ 30% compared with admission. Earlier BNP decreases but not time to diuretics were associated with earlier and greater decreases in hscTnI and urine neutrophil gelatinase-associated lipocalin, and lower incidence of the composite end point. After adjustment for confounders, only no BNP decrease at discharge was significantly associated with mortality but not the composite end point (p = 0.006 and p = 0.062, respectively). In conclusion, earlier time to decongestion but not the time to diuretics was associated with better biomarker trajectories. Residual congestion at discharge rather than the timing of decongestion predicted a worse prognosis.

Potential Utility of Cardiorenal Biomarkers for Prediction and Prognostication of Worsening Renal Function in Acute Heart Failure

BACKGROUND

Multiple different pathophysiologic processes can contribute to worsening renal function (WRF) in acute heart failure.

METHODS AND RESULTS

We retrospectively analyzed 787 patients with acute heart failure for the relationship between changes in serum creatinine and biomarkers including brain natriuretic peptide, high sensitivity cardiac troponin I, galectin 3, serum neutrophil gelatinase-associated lipocalin, and urine neutrophil gelatinase-associated lipocalin. WRF was defined as an increase of greater than or equal to 0.3 mg/dL or 50% in creatinine within first 5 days of hospitalization. WRF was observed in 25% of patients. Changes in biomarkers and creatinine were poorly correlated (r ≤ 0.21) and no biomarker predicted WRF better than creatinine. In the multivariable Cox analysis, brain natriuretic peptide and high sensitivity cardiac troponin I, but not WRF, were significantly associated with the 1-year composite of death or heart failure hospitalization. WRF with an increasing urine neutrophil gelatinase-associated lipocalin predicted an increased risk of heart failure hospitalization.

CONCLUSIONS

Biomarkers were not able to predict WRF better than creatinine. The 1-year outcomes were associated with biomarkers of cardiac stress and injury but not with WRF, whereas a kidney injury biomarker may prognosticate WRF for heart failure hospitalization.

Effect on Survival of Concurrent Hemoconcentration and Increase in Creatinine During Treatment of Acute Decompensated Heart Failure

Hemoconcentration during the treatment of acute decompensated heart failure is a surrogate for plasma volume reduction and is associated with improved survival, but most definitions only allow for hemoconcentration to be determined retrospectively. An increase in serum creatinine can also be a marker of aggressive decongestion, but in isolation is not specific. Our objective was to determine if combined hemoconcentration and worsening creatinine could better identify patients that were aggressively treated and, as such, may have improved postdischarge outcomes. A total of 4,181 patients hospitalized with acute decompensated heart failure were evaluated. Those who experienced both hemoconcentration and worsening creatinine at any point had a profile consistent with aggressive in-hospital treatment and longer length of stay (p <0.01), higher loop diuretic doses (p <0.001), greater weight (p = 0.001), and net fluid loss (p <0.001) compared with the remainder of the cohort. In isolation, neither worsening creatinine (p = 0.11) nor hemoconcentration (p = 0.36) at any time were associated with improved survival. However, patients who experienced both (21%) had significantly better survival (hazard ratio 0.80, 95% confidence interval 0.69 to 0.94, pinteraction = 0.005). In conclusion, this combination of hemoconcentration and worsening creatinine, which can be determined prospectively during patient care, was associated with in-hospital parameters consistent with aggressive diuresis and improved postdischarge survival.

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.

Successful heart-kidney transplantation from a Hepatitis C viremic donor to negative recipient: One year of follow-up

Every year the number of patients waiting for a heart transplant increases faster than the number of available donor organs. Some potential donor organs are from donors with active communicable diseases, including hepatitis C virus (HCV), potentially making donation prohibitive. The advent of direct-acting antiviral agents for HCV has drastically changed the treatment of HCV. Recently, these agents have been used to treat HCV in organ donor recipients who acquired the disease from the donor organ. We report a case of heart-kidney transplantation from an HCV viremic donor to HCV negative recipient with successful treatment and sustained virologic response.

Pro-neurotensin/neuromedin N and risk of ischemic stroke: The REasons for Geographic And Racial Differences in Stroke (REGARDS) study

The tridecapeptide neurotensin has been implicated in the pathogenesis of cardiometabolic disease. Its stable precursor, pro-neurotensin/neuromedin N (pro-NT/NMN), has been associated with composite cardiovascular outcomes including coronary heart disease (CHD) and stroke. The exclusive association of pro-NT/NMN with ischemic stroke has not been evaluated. We conducted a prospective case-cohort study in the REasons for Geographic And Racial Differences in Stroke (REGARDS) study. From 2003 to 2007, REGARDS enrolled 30,239 white or black adults aged ⩾ 45 years. Baseline fasting pro-NT/NMN was measured by immunoassay in the analytic sample including 448 incident ischemic stroke cases and 818 random cohort sample participants. A total of 464 ischemic strokes occurred. Risk of stroke was assessed with a Cox proportional-hazards model incorporating demographic covariates and a second adding stroke risk factors. Increased pro-NT/NMN was associated with ischemic stroke in the demographic model overall (hazard ratio (HR) per standard deviation (SD) pro-NT/NMN 1.16, 95% confidence interval (CI) 1.01-1.33) and in men (HR per SD pro-NT/NMN 1.25, 95% CI 1.04-1.50); HRs were attenuated in the risk factor model. Pre-existing diabetes mellitus and CHD were the largest confounders of ischemic stroke risk, each accounting for an estimated 19% of the association of pro-NT/NMN with ischemic stroke observed in the demographic model. There were no significant interactions of race or sex with pro-NT/NMN. Further research on associations of pro-NT/NMN with stroke risk factors such as diabetes mellitus is indicated.

Advancements in biomarkers for cardiovascular disease: diagnosis, prognosis, and therapy

Biomarkers are essential tools in the practice of cardiology. They assist with diagnosis, prognosis, and guiding therapy in many different cardiovascular diseases. Numerous biomarkers have become strongly associated with different cardiovascular conditions, such as troponin with acute coronary syndrome and natriuretic peptides with heart failure. Even though these biomarkers have been in practice for almost two decades, their uses continue to expand beyond their original roles. Additionally, many new biomarkers have been discovered with increasing utility in cardiovascular disease, including soluble suppression of tumorigenicity 2, galectin 3, and biomarkers of fibrosis, metabolism, and inflammation. How these old and new biomarkers are being expanded into clinical practice is constantly in evolution. This review will highlight some of the recent major advancements in the rapidly evolving field of biomarkers.

Necessity of hospitalization and stress testing in low risk chest pain patients

BACKGROUND

Copeptin is a marker of endogenous stress including early myocardial infarction(MI) and has value in early rule out of MI when used with cardiac troponin I(cTnI).

OBJECTIVES

The goal of this study was to demonstrate that patients with a normal electrocardiogram and cTnI<0.040μg/l and copeptin<14pmol/l at presentation and after 2 h may be candidates for early discharge with outpatient follow-up potentially including stress testing.

METHODS

This study uses data from the CHOPIN trial which enrolled 2071 patients with acute chest pain. Of those, 475 patients with normal electrocardiogram and normal cTnI(<0.040μg/l) and copeptin<14pmol/l at presentation and after 2 h were considered "low risk" and selected for further analysis.

RESULTS

None of the 475 "low risk" patients were diagnosed with MI during the 180day follow-up period (including presentation). The negative predictive value of this strategy was 100% (95% confidence interval(CI):99.2%-100.0%). Furthermore no one died during follow up. 287 (60.4%) patients in the low risk group were hospitalized. In the "low risk" group, the only difference in outcomes (MI, death, revascularization, cardiac rehospitalization) was those hospitalized underwent revascularization more often (6.3%[95%CI:3.8%-9.7%] versus 0.5%[95%CI:0.0%-2.9%], p=.002). The hospitalized patients were tested significantly more via stress testing or angiogram (68.6%[95%CI:62.9%-74.0%] vs 22.9%[95%CI:17.1%-29.6%], p<.001). Those tested had less cardiac rehospitalizations during follow-up (1.7% vs 5.1%, p=.040).

CONCLUSIONS

In conclusion, patients with a normal electrocardiogram, troponin and copeptin at presentation and after 2 h are at low risk for MI and death over 180days. These low risk patients may be candidates for early outpatient testing and cardiology follow-up thereby reducing hospitalization.

Acute right heart failure caused by tacrolimus after renal transplantation: Serial observation by speckle tracking and Doppler echocardiography

Tacrolimus is an immunosuppressive agent well known to be capable of producing renal impairment. Acute renal failure with right heart failure caused by tacrolimus is rarely described. We report the findings of one such case in which tacrolimus caused acute renal failure with severe tricuspid regurgitation and right ventricular failure documented by echocardiography.