Diuresis-Related Weight Loss Reflects Interstitial Compartment Decongestion with Minimal Impact on Intravascular Volume Expansion or Outcomes in Post-Acute Heart Failure: Metrics of Decongestion and Volume Status

Full decongestion in acute heart failure therapy

Incomplete decongestion is the main cause of readmission in the early post-discharge period of a hospitalization for acute heart failure. Recent heart failure guidelines have highlighted initiation and rapid up-titration of quadruple therapy with angiotensin receptor neprilysin inhibitor, beta adrenergic receptor blocker, mineralocorticoid receptor antagonist, and sodium glucose cotransporter 2 inhibitor to prevent hospitalizations for heart failure with reduced ejection fraction. However, full decongestion remains the foremost therapeutic goal of hospitalization for heart failure. While early addition of sodium glucose cotransporter 2 inhibitors and mineralocorticoid receptor antagonists may be helpful, the value of the other therapeutics comes after decongestion is complete.

Evaluation and Management of Hyponatremia in Heart Failure

PURPOSE OF REVIEW

To provide a contemporary overview of the pathophysiology, evaluation, and treatment of hyponatremia in heart failure (HF).

RECENT FINDINGS

Potassium and magnesium losses due to poor nutritional intake and treatment with diuretics cause an intracellular sodium shift in HF that may contribute to hyponatremia. Impaired renal blood flow leading to a lower glomerular filtration rate and increased proximal tubular reabsorption lead to an impaired tubular flux through diluting distal segments of the nephron, compromising electrolyte-free water excretion. Hyponatremia in HF is typically a condition of impaired water excretion by the kidneys on a background of potassium and magnesium depletion. While those cations can and should be easily repleted, further treatment should mainly focus on improving the underlying HF and hemodynamics, while addressing congestion. For decongestive treatment, proximally acting diuretics such as sodium-glucose co-transporter-2 inhibitors, acetazolamide, and loop diuretics are the preferred options.

Serial blood volume measurements in patients with compensated chronic heart failure: How do volume profiles change over time?

Among patients with chronic heart failure (HF) intravascular volume profiles vary significantly despite similar clinical compensation. However, little is known regarding changes in blood volume (BV) profiles over time. The objective of this analysis was to identify the extent and character of changes in volume profiles over time. A prospective analysis was undertaken in patients who were hospitalized and treated for fluid overload. Quantitative BV analyses were obtained in a compensated state at hospital discharge (baseline) and follow-up at 1, 3, and 6 mo. Data were available on 10 patients who remained stable without rehospitalization or medication change over a 6-mo period. Baseline BV profiles were highly variable at hospital discharge with an average deviation of +28% above normal in 6 patients and normal BV in 4 patients. Over the follow-up period, the median change in BV was -201 mL [-3% (-6, +3%)] from baseline with profiles remaining in the same volume category in 9 out of 10 patients. Crossover from normal BV to mild contraction (-13% of normal) occurred in one patient. Red blood cell mass demonstrated the largest change over 6 mo [median -275 (-410, +175) mL] with a deviation from normal of -14 (-20, +8) % (reflecting mild anemia). These findings suggest that BV profiles in clinically compensated patients with HF do not change substantially over a 6-mo period regardless of baseline expanded or normal BV. This lack of change in volume profiles particularly from an expanded BV has implications for long-term volume management, clinical outcomes, and also our understanding of volume homeostasis in HF.NEW & NOTEWORTHY The novel findings of this study demonstrate that blood volume profiles while highly variable in clinically compensated patients with HF on stable medical therapy do not change substantially over a 6-mo period regardless of baseline expanded or normal blood volumes. This lack of change in volume profiles particularly from an expanded blood volume has implications for long-term volume management and also for how we understand the pathophysiology of volume homeostasis in chronic HF.

Critical Analysis of the Effects of SGLT2 Inhibitors on Renal Tubular Sodium, Water and Chloride Homeostasis and Their Role in Influencing Heart Failure Outcomes

SGLT2 (sodium-glucose cotransporter 2) inhibitors interfere with the reabsorption of glucose and sodium in the early proximal renal tubule, but the magnitude and duration of any ensuing natriuretic or diuretic effect are the result of an interplay between the degree of upregulation of SGLT2 and sodium-hydrogen exchanger 3, the extent to which downstream compensatory tubular mechanisms are activated, and (potentially) the volume set point in individual patients. A comprehensive review and synthesis of available studies reveals several renal response patterns with substantial variation across studies and clinical settings. However, the common observation is an absence of a large acute or chronic diuresis or natriuresis with these agents, either when given alone or combined with other diuretics. This limited response results from the fact that renal compensation to these drugs is rapid and nearly complete within a few days or weeks, preventing progressive volume losses. Nevertheless, the finding that fractional excretion of glucose and lithium (the latter being a marker of proximal sodium reabsorption) persists during long-term treatment with SGLT2 inhibitors indicates that pharmacological tolerance to the effects of these drugs at the level of the proximal tubule does not meaningfully occur. This persistent proximal tubular effect of SGLT2 inhibitors can be hypothesized to produce a durable improvement in the internal set point for volume homeostasis, which may become clinically important during times of fluid expansion. However, it is difficult to know whether a treatment-related change in the volume set point actually occurs or contributes to the effect of these drugs to reduce the risk of major heart failure events. SGLT2 inhibitors exert cardioprotective effects by a direct effect on cardiomyocytes that is independent of the presence of or binding to SGLT2 or the actions of these drugs on the proximal renal tubule. Nevertheless, changes in the volume set point mediated by SGLT2 inhibitors might potentially act cooperatively with the direct favorable molecular and cellular effects of these drugs on cardiomyocytes to mediate their benefits on the development and clinical course of heart failure.

Measurement of Blood Volume in Patients with Heart Failure: Clinical Relevance, Surrogates, Historical Background and Contemporary Methodology

The development of clinical congestion resulting from volume overload, either by renal fluid retention or redistribution of blood volume from venous reservoirs, is a recurrent scenario in patients with chronic heart failure (HF). As a result, the treatment of congestion, most commonly by initiating aggressive diuretic therapy, is a front-line issue in the management of patients with HF. However, the association of clinical congestion and volume overload with physical signs and symptoms, as well as other surrogates of volume assessment, has limitations in accuracy and, therefore, reliability to direct appropriate interventions. The ability to quantitate intravascular volume and identify the variability in volume profiles among patients with HF can uniquely inform individualized volume management and aid in risk stratification. This tool is provided by contemporary nuclear medicine-based BVA-100 methodology, which uses the well-established indicator-dilution principle and is a requested topic for discussion in this review.

Body fluid regulation via chronic inhibition of sodium-glucose cotransporter-2 in patients with heart failure: a post hoc analysis of the CANDLE trial

BACKGROUND

In patients with chronic heart failure (CHF) and type 2 diabetes (T2D), sodium-glucose cotransporter-2 (SGLT2) inhibition improves cardiorenal outcomes, but details of the effects on distinct subsets of body fluid volume remain incomplete.

METHODS

This was a post hoc analysis of patients with CHF and T2D in the CANDLE trial (UMIN000017669), an investigator-initiated, multi-center, randomized open-label trial that compared the effect of canagliflozin (100 mg, n = 113) with glimepiride (starting dose: 0.5 mg, n = 120) on changes in N-terminal pro-brain natriuretic peptide. The estimated plasma volume (ePV, calculated with the Straus formula) and estimated extracellular volume (eEV, determined by the body surface area) were compared between treatment groups at weeks 4, 12, and 24.

RESULTS

Among 233 patients analyzed, 166 (71.2%) had an ejection fraction (EF) > 50%. Reductions in ePV and eEV were observed only in the canagliflozin group until week 12 (change from baseline at week 12, ePV; - 7.63%; 95% confidence interval [CI], - 10.71 to - 4.55%, p < 0.001, eEV; - 123.15 mL; 95% CI, - 190.38 to - 55.92 mL, p < 0.001). While ePV stopped falling after week 12, eEV continued to fall until week 24 ([change from baseline at week 24] - [change from baseline at week 12], ePV; 1.01%; 95%CI, - 2.30-4.32%, p = 0.549, eEV; - 125.15 mL; 95% CI, - 184.35 to - 65.95 mL, p < 0.001).

CONCLUSIONS

Maintenance of a modest reduction in ePV and continuous removal of eEV via chronic SGLT2 inhibition suggests that favorable body fluid regulation contributes to the cardiorenal benefits of SGLT2 inhibitors in patients with CHF, irrespective of EF.

TRIAL REGISTRATION

UMIN000017669.

Fluid Volume Homeostasis in Heart Failure: A Tale of 2 Circulations

Fluid volume homeostasis in health and heart failure (HF) requires a complex interaction of 2 systems, the intravascular and interstitial-lymphatic circulations. With the development of HF both the intravascular and interstitial compartments undergo variable degrees of volume remodeling which can include significant expansion. This reflects the impact of multiple pathophysiologic mechanisms on both fluid compartments which initially play a compensatory role to stabilize intravascular circulatory integrity but with progression in HF can evolve to produce the various manifestations of volume overload and clinical HF congestion. The intent of this review is to help enhance recognition of the pathophysiologic and clinical importance of the interlinked roles of these 2 circulatory systems in volume regulation and chronic HF. It would also be hoped that a better understanding of the interacting functions of the intravascular and interstitial-lymphatic fluid compartments can potentially aid development of novel management strategies particularly addressing the generally undertargeted interstitial-lymphatic system and help bring such approaches forward through a more integrated view of these 2 circulatory systems.

Worsening of Renal Function Among Hospitalized Patients With Acute Heart Failure: Phenotyping, Outcomes, and Predictors

OBJECTIVE

To define clinical phenotyping and its associated outcome of worsening of renal function (WRF) in hospitalized acute heart failure (AHF) patients.

PATIENTS AND METHODS

Latent class analysis was performed in 113 AHF patients who developed WRF within 72 hours in the DOSE (Diuretic Optimization Strategies Evaluation) trial (from March 2008 to November 2009) and ROSE-AHF (Renal Optimization Strategies Evaluation in Acute Heart Failure) trial (from September 2010 to March 2013) to identify potential WRF phenotypes. Clinical characteristics and outcome (in-hospital and post-discharge) were compared between different phenotypes.

RESULTS

Two WRF phenotypes were identified by latent class analysis, which we named WRF minimally responsive to diuretics (WRF-MRD) and WRF responsive to diuretics (WRF-RD). Among the population, 58 (9.5%) developed WRF-MRD and 55 (9.0%) developed WRF-RD. Patients with WRF-MRD had more comorbidities than WRF-RD. In WRF-MRD, there were an early increase in serum creatinine, a smaller amount of net fluid loss and weight loss, and a higher rate of worsening or persistent heart failure over 72 hours. In contrast, for those with WRF-RD, they had faster in-hospital net fluid loss and weight loss and a better 60-day survival after discharge even compared with patients without WRF (P=.004). Furthermore, baseline chronic obstructive pulmonary disease, diabetes, and cystatin C were independent predictors of WRF-MRD, whereas serum hemoglobin and sodium predicted WRF-RD.

CONCLUSIONS

Among hospitalized AHF patients, we identified two phenotypes of WRF with distinct response to heart failure treatment, predictors, and short-term prognosis after discharge. The results could help early differentiation of WRF phenotypes in clinical practice.

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.

Quantitative Blood Volume Analysis and Hemodynamic Measures of Vascular Compliance in Patients with Worsening Heart Failure: BVA and Hemodynamic Profiles in Worsening HF

BACKGROUND

The role of blood volume (BV) expansion versus a change in vascular compliance in worsening heart failure (HF) remains under debate. We aimed to assess the relationship between BV and resting and stress hemodynamics in worsening HF, and to further elucidate the significance of BV in cardiac decompensation.

METHODS AND RESULTS

Patients with worsening HF underwent radiolabeled indicator-dilution BV analysis and cardiac catheterization. Intravascular volumes and resting/stress hemodynamics were recorded. Provocative stress maneuvers included change in systolic blood pressure (ΔSBP) from lying to standing and Valsalva, and intracardiac pressure changes with leg raise. Correlation between BV and invasive hemodynamics were assessed by linear regression. Of 27 patients with worsening HF, patient characteristics included mean age 61±12 years, 70% male, 19% Black, and mean ejection fraction 29±15%. Thirteen (48%) had hypervolemia measured by total BV (TBV). TBV weakly correlated with ΔSBP by position (R²=0.009) and Valsalva (R²=0.003), and with right atrial (R²=0.049) and pulmonary capillary wedge (R²=0.047) pressure changes during leg raise.

CONCLUSIONS

In patients with worsening HF, BV mildly correlated with intracardiac pressures at rest. Provocative maneuvers intended to test vascular compliance did not correlate with BV, indicating that compliance may serve as a standalone metric in HF.

Deviations From the Ideal Plasma Volume and Isolated Tricuspid Valve Surgery—Paving the Way for New Risk Stratification Parameters

Background

Congestion and plasma volume expansion are important features of heart failure, whose prognostic significance has been investigated in a range of surgical and non-surgical settings. The aim of this study was to evaluate the value of the estimated plasma volume status (ePVS) in patients undergoing isolated tricuspid valve surgery.

Methods

This study included patients who underwent isolated tricuspid valve surgery at the Vienna General Hospital (Austria) between July 2008 and November 2018. The PVS cut-off was calculated using ROC analysis and Youden's Index.

Results

Eighty eight patients (median age: 58 [IQR: 35-70] years; 44.3% male; 75.6% NYHA III/IV; median EuroSCORE II 2.65 [IQR: 1.70-5.10]; 33.0% endocarditis-related regurgitation; 60.2% isolated repair; 39.8% isolated replacement) were included in this study. Patients who died within 1 year following surgery had significantly higher baseline ePVS values than survivors (median ePVS 5.29 [IQR: −1.55-13.55] vs. −3.68 [IQR: −10.92-4.22]; p = 0.005). During a median actuarial follow-up of 3.02 (IQR: 0.36-6.80) years, patients with a preoperative ePVS ≥ −4.17 had a significantly increased mortality (log-rank p = 0.006).

Conclusions

ePVS is an easily obtainable risk parameter for patients undergoing isolated tricuspid valve surgery capable of predicting mid- and long-term outcomes after isolated tricuspid valve surgery.

Assessment of Phasic Changes of Vascular Size by Automated Edge Tracking-State of the Art and Clinical Perspectives

Assessment of vascular size and of its phasic changes by ultrasound is important for the management of many clinical conditions. For example, a dilated and stiff inferior vena cava reflects increased intravascular volume and identifies patients with heart failure at greater risk of an early death. However, lack of standardization and sub-optimal intra- and inter- operator reproducibility limit the use of these techniques. To overcome these limitations, we developed two image-processing algorithms that quantify phasic vascular deformation by tracking wall movements, either in long or in short axis. Prospective studies will verify the clinical applicability and utility of these methods in different settings, vessels and medical conditions.

In-Hospital Weight Loss and Outcomes in Patients With Heart Failure

BACKGROUND

Acute decompensation of heart failure (HF) is often marked by fluid retention, and weight loss is a marker of successful diuresis. We examined the relationship between in-hospital weight loss and post-discharge outcomes in patients with HF.

METHODS

We conducted a propensity score-matched study of 8830 patients hospitalized for decompensated HF in the Medicare-linked Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients with Heart Failure (OPTIMIZE-HF) registry, in which 4415 patients in the weight-loss group and 4415 patients in the no-weight-loss group were balanced on 75 baseline characteristics. We defined weight loss as an admission-to-discharge weight loss of 1-30 kilograms, and we defined no weight loss as a weight gain or loss of < 1 kilogram. Hazard ratios (HRs) and 95% confidence intervals (CIs) for outcomes associated with weight loss were estimated.

RESULTS

Patients had a mean age of 78 years, 57% were women, and 11% were African American. The median weight loss in the weight-loss group was 3.6 (interquartile range, 2.0-6.0) kilograms. HRs and 95% CIs for 30-day all-cause mortality, all-cause readmission and HF readmission associated with weight loss were 0.75 (0.63-0.90), 0.90 (0.83-0.99) and 0.83 (0.72-0.96), respectively. Respective 60-day HRs (95% CIs) were 0.80 (0.70-0.92), 0.91 (0.85-0.98) and 0.88 (0.79-0.98). These associations were attenuated and lost significance during 6 months of follow-up.

CONCLUSIONS

Among older patients hospitalized for decompensated HF, in-hospital weight loss was associated with a lower risk of mortality and hospital readmission. These findings suggest that in-hospital weight loss, a marker of successful diuresis and decongestion, is also a marker of improved clinical outcomes.

Blood volume expansion, normovolemia, and clinical outcomes in chronic human heart failure: more is better

Expansion in blood volume (BV) is a well-recognized response to arterial underfilling secondary to impaired cardiac output in heart failure (HF). However, the effectiveness of this response in terms of outcomes remains inadequately understood. Prospective analysis was undertaken in 110 patients with HF hospitalized and treated for fluid overload. BVs were measured in a compensated state at the hospital discharge using the indicator-dilution methodology. Data were analyzed for composite 1-year HF-related mortality/first rehospitalization. Despite uniform standard of care, marked heterogeneity in BVs was identified across the cohort. The cohort was stratified by BV expansion greater than or equal to +25% above normal (51% of cohort), mild-moderate expansion (22%), and normal BV (27%). Kaplan-Meier (K-M) survival estimates and regression analyses revealed BV expansion (greater than or equal to +25%) to be associated with better event-free survival relative to normal BV (P = 0.038). Increased red blood cell mass (RBCm; RBC polycythemia) was identified in 43% of the overall cohort and 70% in BV expansion greater than or equal to +25%. K-M analysis demonstrated polycythemia to be associated with better outcomes compared with normal RBCm (P < 0.002). Persistent BV expansion to include RBC polycythemia is common and, importantly, associated with better clinical outcomes compared with normal total BV or normal RBCm in patients with chronic HF. However, compensatory BV expansion is not a uniform physiological response to the insult of HF with marked variability in BV profiles despite uniform standard of care diuretic therapy. Therefore, recognizing the variability in volume regulation pathophysiology has implications not only for impact on clinical outcomes and risk stratification but also potential for informing individualized volume management strategies.NEW & NOTEWORTHY The novel findings of this study demonstrate that intravascular volume profiles among the patients with chronic heart failure (HF) vary substantially even with similar clinical compensation. Importantly, a profile of blood volume (BV) expansion (compared with a normal BV) is associated with lower HF mortality/morbidity. Furthermore, RBC polycythemia is common and independently associated with improved outcomes. These observations support BV expansion with RBC polycythemia as a compensatory mechanism in chronic HF.