Renal Dysfunction in Heart Failure With Preserved Ejection Fraction: Insights From the RELAX Trial

Sudden Cardiac Death Risk Stratification in Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) poses a significant clinical challenge, with sudden cardiac death (SCD) emerging as one of the leading causes of mortality. Despite advancements in cardiovascular medicine, predicting and preventing SCD in HFpEF remains complex due to multifactorial pathophysiological mechanisms and patient heterogeneity. Unlike heart failure with reduced ejection fraction, where impaired contractility and ventricular remodeling predominate, HFpEF pathophysiology involves heavy burden of comorbidities such as hypertension, obesity, and diabetes. Diverse mechanisms, including diastolic dysfunction, microvascular abnormalities, and inflammation, also contribute to distinct disease and SCD risk profiles. Various parameters such as clinical factors and electrocardiogram features have been proposed in SCD risk assessment. Advanced imaging modalities and biomarkers offer promise in risk prediction, yet comprehensive risk stratification models specific to HFpEF ar0e lacking. This review offers recent evidence on SCD risk factors and discusses current therapeutic strategies aimed at reducing SCD risk in HFpEF.

Determinants of Anaerobic Threshold at Each Stage of Renal Dysfunction in Patients With Heart Disease

Patients with heart disease have a low anaerobic threshold (AT), and the determinants of AT may differ, depending on the severity of renal dysfunction. This study aimed to verify the determinants of AT for each stage of renal function in patients with heart disease. We consecutively enrolled 250 patients with heart disease who underwent cardiopulmonary exercise testing in our institution. The patients were divided into 3 groups by their estimated glomerular filtration rate (eGFR): <45, 45 to 59, and ≥60 ml/min/1.73 m2. A multivariate linear regression analysis was performed to evaluate the independent determinants of AT for each group. In total, 201 patients were analyzed. AT decreased with the deterioration of renal function (eGFR <45, 10.9 ± 2.1 vs eGFR 45 to 59, 12.4 ± 2.5 vs eGFR ≥60, 14.0 ± 2.6 ml/min/kg, p <0.001). In the eGFR <45 group, left ventricular ejection fraction and hemoglobin were significantly associated with AT (β = 0.427, p = 0.006 and β = 0.488, p = 0.002, respectively). In the eGFR 45 to 59 and ≥60 groups, ΔPETO2 (end-tidal oxygen partial pressure from rest to AT) showed a significant association with AT (β = 0.576, p <0.001 and β = 0.308, p = 0.003, respectively). The determinants of AT depended on the stage of renal dysfunction in patients with heart disease. In conclusion, in the eGFR <45 group, the determinants of AT were left ventricular ejection fraction and hemoglobin, whereas in the eGFR 45 to 59 and eGFR ≥60 groups, the determinant of AT was ΔPETO2.

Sildenafil and Kidney Function in Heart Failure with Preserved Ejection Fraction

Key Points

Sildenafil induced an acute effect on eGFR without change in the overall eGFR slope after 24 weeks in a heart failure with preserved ejection fraction (HFpEF) cohort. N -terminal pro–brain natriuretic peptide levels and baseline diuretic use were most strongly associated with eGFR decline in this HFpEF cohort. Long-term studies are required to determine sildenafil's influence on kidney function and outcomes in HFpEF.

Background

CKD worsens the prognosis for people with heart failure with preserved ejection fraction (HFpEF). In the Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in Diastolic HFpEF (RELAX) trial, sildenafil decreased eGFR compared with placebo despite favorable kidney effects in preclinical models. Since acute eGFR decline precedes long-term kidney benefits for select medications, we assessed the influence of sildenafil on acute and chronic eGFR slopes.

Methods

The RELAX trial randomized 216 participants to placebo or sildenafil and assessed 24-week changes in cardiopulmonary exercise testing, cardiovascular imaging, and laboratory data. We applied linear mixed modeling to calculate the total, acute (0–12 weeks), and chronic (3–24 weeks) eGFR slopes by treatment. Using regression modeling, we assessed respective associations between eGFR slope and baseline data and clinical end points. We repeated the analyses using a binary outcome on the basis of a substantial (≥20%) decline in eGFR.

Results

The mean baseline eGFR was 60.8 ml/min per 1.73 m2, and the mean eGFR slope during follow-up was −3.21 ml/min per 1.73 m2 per year. Sildenafil did not alter total eGFR slope compared with placebo (difference +0.47 ml/min per 1.73 m2 per year, 95% confidence interval [CI], −6.63 to 7.57 ml/min per 1.73 m2 per year). Sildenafil users tended to experience a more negative acute eGFR slope (difference −3.15 ml/min per 1.73 m2 per year) and more positive chronic slope (+2.06 ml/min per 1.73 m2 per year) compared with placebo, but neither difference reached statistical significance. Baseline N -terminal pro–B-type natriuretic peptide and loop diuretic use were associated with worse eGFR trajectory regardless of treatment. Substantial eGFR decline was associated with increase in endothelin-1 and a greater risk of hospitalization or death (HR, 2.34, 95% CI, 1.21 to 4.53, P =0.01).

Conclusions

Sildenafil induced an acute effect on eGFR without change in the overall eGFR slope after 24 weeks in an HFpEF cohort, suggesting lack of long-term risk related to early reduction in eGFR after initiating treatment. Long-term studies are needed to determine the effect of sildenafil on kidney function in HFpEF.

How to Manage Heart Failure With Preserved Ejection Fraction: Practical Guidance for Clinicians

Although patients with heart failure with preserved ejection fraction (HFpEF) (left ventricular ejection fraction ≥50%) comprise nearly half of those with chronic heart failure, evidence-based treatment options for this population have historically been limited. Recently, however, emerging data from prospective, randomized trials enrolling patients with HFpEF have greatly altered the range of pharmacologic options to modify disease progression in selected patients with HFpEF. In the context of this evolving landscape, clinicians are increasingly in need of practical guidance regarding the best approach to management of this growing population. In this review, we build on the recently published heart failure guidelines by integrating contemporary data from recent randomized trials to provide a contemporary framework for diagnosis and evidence-based treatment of patients with HFpEF. Where gaps in knowledge persist, we provide "best available" data from post hoc analyses of clinical trials or data from observational studies to guide management until more definitive studies are available.

Systemic immune-inflammation index as a prognostic marker for advanced chronic heart failure with renal dysfunction

AIMS

We aim to investigate the correlation between high levels of the systemic immune-inflammation index (SII) and long-term mortality and major cardiovascular adverse events in advanced chronic heart failure patients with renal dysfunction.

METHODS AND RESULTS

Seven hundred seventeen advanced chronic heart failure patients with renal dysfunction, who visited the First affiliated hospital of Zhengzhou University from September 2019 to December 2020, were included. All-cause mortalities (ACM) were selected as primary endpoints and major cardiovascular adverse events (MACEs) as the secondary endpoints. Based on the receiver operating characteristic (ROC) curve and the Youden index, the optimal cut-off values of SII for ACM and MACEs were 1228 and 1406. In the group where ACM were the primary endpoint, patients were categorized into the low-SII group (n = 479) and the high-SII group (n = 238). Patients in the group using MACEs as the secondary endpoint were also categorized into the low-SII groups (n = 514) and the high-SII groups (n = 203). Univariate and multivariate COX regression were used to screen the independent predictors for ACM and MACEs, revealing the relationship between SII levels and endpoints. According to the univariate COX analysis, SII was the risk factor (hazard ratio [HR] = 2.144, 95% confidence interval [CI]: 1.565-2.938, P < 0.001) for the ACM subgroup. It was also the risk factor (HR = 1.625, CI: 1.261-2.905, P < 0.001) for the MACEs subgroup. Multivariate COX regression analysis indicated that the occurrence of ACM and MACEs in high-level SII and low-level SII patients had statistical differences. The incidence of ACM increased by 70.3% (HR = 1.703; 95% CI: 1.200-2.337; P = 0.002) in patients of the high SII level group, the incidence of MACEs increased by 58.3% (HR = 1.583, 95% CI: 1.213-2.065, P = 0.001). Kaplan-Meier (K-M) survival analysis further suggested that patients with a high SII level had an increased risk of having ACM (log-rank P < 0.001) and MACEs (log-rank P < 0.001) within 30 months. SII could be considered as a novel predictor of the occurrence of ACM and MACEs for patients with advanced chronic heart failure and renal dysfunction.

CONCLUSIONS

This study suggested that SII is a novel independent predictor of mortality in advanced chronic heart failure patients with renal dysfunction, and it should be considered in current clinical management.

Biomarkers in HFpEF for Diagnosis, Prognosis, and Biological Phenotyping

PURPOSE OF REVIEW

The heterogeneity of heart failure with preserved ejection fraction (HFpEF) is responsible for the limited success of broad management strategies. The role of biomarkers has been evolving helping to provide insight into the diversity of pathophysiology, prognosis, and potential targets for treatments. We will review the role of traditional and novel biomarkers in diagnosing, prognosticating, and evolving the management of patients with HFpEF. As circulating biomarker discovery rapidly evolves, we will explore technology for new biomarker discovery with examples of successful implementation.

RECENT FINDINGS

Besides cardiac-specific biomarkers (natriuretic peptides and troponin), other novel nonspecific biomarkers increasingly identify the diversity of pathophysiological mechanisms of HFpEF including inflammation, fibrosis, and renal dysfunction. Newer approaches have provided increasing granularity providing opportunities to integrate large amounts of information from proteomics and genomics as biomarkers of interest in HFpEF. HFpEF has been marked with failure of many medications to show benefit, whether measuring single targeted biomarkers or broader targeted discovery proteomics or genomic circulating biomarkers are providing increasing opportunities to better understand and manage HFpEF patients.

Determinants of Peak Oxygen Uptake at Each Stage of Renal Dysfunction in Patients with Heart Disease

Background

Identifying the causes of low peak oxygen uptake (peak V̇ O 2 ) in heart disease patients with renal dysfunction is necessary for prognostic improvement strategies. The purpose of this study was to verify the determinants of peak V̇ O 2 for each stage of renal function in heart disease patients, focusing on end-tidal oxygen partial pressure ( PETO 2 ).

Methods

Two hundred fifty heart disease patients who underwent cardiopulmonary exercise testing (CPET) in our institution were consecutively enrolled. Patients were divided into three groups by their estimated glomerular filtration rate (eGFR): < 45, 45-59 and ≥ 60 mL/min/1.73 m 2 . Patient characteristics and CPET parameters including Δ 2 (rest-anaerobic threshold) were compared between the groups. The relationship between Δ PETO PETO 2 and peak V̇ O 2 was also investigated for each group.

Results

In total, 201 patients were analyzed. Δ PETO 2 decreased with the deterioration of renal function (eGFR < 45, 0.1 mmHg vs. eGFR 45-59, 2.4 mmHg vs. eGFR ≥ 60, 5.2 mmHg, p < 0.001). In the eGFR < 45 group, left ventricular ejection fraction (LVEF) and hemoglobin (Hb) were significantly associated with peak V̇ O 2 β = 0.518, p < 0.001 and β = 0.567, p < 0.001, respectively), whereas Δ PETO 2 was not. In the eGFR 45-59 group, age, Hb, and Δ PETO 2 showed a significant association with peak V̇ O 2 ( β = -0.354, p = 0.006; β = 0.258, p = 0.007; β = 0.501, p < 0.001; respectively). In the univariate analysis, eGFR 45-59 group showed the highest coefficient of determination of Δ PETO 2 to peak V̇ O 2 ( R 2 = 0.247, p < 0.001).

Conclusions

The determinants of peak V̇ O 2 in heart disease patients depended on the stage of renal function. The determinants of peak V̇ O 2 in patients with eGFR < 45 were LVEF and Hb, while Δ PETO 2 was the strongest predictor of peak V̇ O 2 in patients with eGFR 45-59.

Impaired pulmonary vasomotor control in exercising swine with multiple comorbidities

Pulmonary hypertension is common in heart failure with preserved ejection fraction (HFpEF). Here, we tested the hypothesis that comorbidities [diabetes mellitus (DM, streptozotocin), hypercholesterolemia (HC, high-fat diet) and chronic kidney disease (CKD, renal microembolization)] directly impair pulmonary vasomotor control in a DM + HC + CKD swine model. 6 months after induction of DM + HC + CKD, pulmonary arterial pressure was similar in chronically instrumented female DM + HC + CKD (n = 19) and Healthy swine (n = 18). However, cardiac output was lower both at rest and during exercise, implying an elevated pulmonary vascular resistance (PVR) in DM + HC + CKD swine (153 ± 10 vs. 122 ± 9 mmHg∙L^-1∙min∙kg). Phosphodiesterase 5 inhibition and endothelin receptor antagonism decreased PVR in DM + HC + CKD (- 12 ± 12 and - 22 ± 7 mmHg∙L^-1∙min∙kg) but not in Healthy swine (- 1 ± 12 and 2 ± 14 mmHg∙L^-1∙min∙kg), indicating increased vasoconstrictor influences of phosphodiesterase 5 and endothelin. Inhibition of nitric oxide synthase produced pulmonary vasoconstriction that was similar in Healthy and DM + HC + CKD swine, but unmasked a pulmonary vasodilator effect of endothelin receptor antagonism in Healthy (- 56 ± 26 mmHg∙L^-1∙min∙kg), whereas it failed to significantly decrease PVR in DM + HC + CKD, indicating loss of nitric oxide mediated inhibition of endothelin in DM + HC + CKD. Scavenging of reactive oxygen species (ROS) had no effect on PVR in either Healthy or DM + HC + CKD swine. Cardiovascular magnetic resonance imaging, under anesthesia, showed no right ventricular changes. Finally, despite an increased contribution of endogenous nitric oxide to vasomotor tone regulation in the systemic vasculature, systemic vascular resistance at rest was higher in DM + HC + CKD compared to Healthy swine (824 ± 41 vs. 698 ± 35 mmHg∙L^-1∙min∙kg). ROS scavenging induced systemic vasodilation in DM + HC + CKD, but not Healthy swine. In conclusion, common comorbidities directly alter pulmonary vascular control, by enhanced PDE5 and endothelin-mediated vasoconstrictor influences, well before overt left ventricular backward failure or pulmonary hypertension develop.

Renal Dysfunction and Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) and chronic kidney disease (CKD) constitute a high-risk phenotype with significant morbidity and mortality and poor prognosis. Multiple proinflammatory comorbid conditions influence the pathogenesis of HFpEF and CKD. Renal dysfunction in HFpEF is a consequence of the complex interplay between hemodynamic factors, systemic congestion, inflammation, endothelial dysfunction, and neurohormonal mechanisms. In contrast to heart failure with reduced ejection fraction, there is a dearth of effective targeted therapies for HFpEF. Tailoring study design toward the different phenotypes and delving into their pathophysiology may be fruitful in development of effective phenotype-specific targeted pharmaceutical therapies.

Association of Visit-to-Visit Variability in Kidney Function and Serum Electrolyte Indexes With Risk of Adverse Clinical Outcomes Among Patients With Heart Failure With Preserved Ejection Fraction

Importance

Although kidney dysfunction and abnormalities in serum electrolyte levels are associated with poor clinical outcomes in patients with heart failure with preserved ejection fraction (HFpEF), the association of visit-to-visit variability in such laboratory measures with long-term outcomes is unclear.

Objective

To evaluate the associations of visit-to-visit variability in indexes of kidney function (creatinine and blood urea nitrogen [BUN] levels) and serum electrolyte (sodium, chloride, and potassium) with the risk of adverse clinical outcomes among patients with chronic, stable HFpEF.

Design, Setting, and Participants

This cohort analysis used data from the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist (TOPCAT) trial. All participants with 3 or more serial laboratory measurements who were event free within the first 4 months of enrollment were included. Data were analyzed from March 1, 2019, to January 31, 2020.

Main Outcomes and Measures

Adjusted associations between indexes of variability in serum laboratory measurements during the first 4 months of follow-up and risk of the primary composite outcome (a composite of aborted cardiac arrest, hospitalization for heart failure, or cardiovascular death) and all-cause mortality were assessed using Cox proportional hazards regression models.

Results

Of the 3445 patients enrolled in the TOPCAT trial (mean [SD] age, 68-69 [10] years; 49.7%-51.5% female), 2479 (BUN) to 3195 (potassium) were analyzed, depending on availability of serial measurements. Participants with higher laboratory variability in kidney function parameters were older, had more comorbidities, and had more severe symptoms of HFpEF. Higher visit-to-visit variability in BUN (hazard ratio [HR] per 1-SD higher average successive variability [ASV], 1.21; 95% CI, 1.10-1.33) and creatinine (HR per 1-SD higher ASV, 1.13; 95% CI, 1.04-1.22) were independently associated with a higher risk of the primary composite outcome as well as mortality independent of other baseline confounders, changes in kidney function, changes in medication dosages, and variability in other cardiometabolic parameters (systolic blood pressure and body mass index). The higher risk associated with greater variability in kidney function was consistent across subgroups of patients stratified by the presence of chronic kidney disease (CKD) at baseline (CKD: HR per 1-SD higher ASV, 1.39; 95% CI, 1.16-1.67 and no CKD: HR per 1-SD higher ASV, 1.13; 95% CI, 1.01-1.27), among placebo and spironolactone treatment arms separately (spironolactone arm: 1.30; 95% CI, 1.03-1.65 and placebo arm: HR per 1-SD higher ASV, 1.27; 95% CI, 1.04-1.56). Among serum electrolytes, variability in sodium and potassium measures were also significantly associated with a higher risk of primary composite events (sodium: HR per 1-SD higher ASV, 1.14; 95% CI, 1.01-1.30 and potassium: HR per 1-SD higher ASV, 1.21; 95% CI, 1.02-1.44).

Conclusions and Relevance

In HFpEF, visit-to-visit variability in laboratory indexes of kidney function and serum electrolytes is common and independently associated with worse long-term clinical outcomes.

Fibroblast Growth Factor 23 and Exercise Capacity in Heart Failure with Preserved Ejection Fraction

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) is characterized by left ventricular hypertrophy and decreased exercise capacity. Fibroblast growth factor 23 (FGF23), a hormone involved in phosphate, vitamin D, and iron homeostasis, is linked to left ventricular hypertrophy and HF. We measured c-terminal FGF23 (cFGF23) and intact FGF23 (iFGF23) levels and examined their associations with exercise capacity in patients with HFpEF.

METHODS AND RESULTS

Using multivariable linear regression and linear mixed models, we studied the associations of cFGF23 and iFGF23 with baseline and mean weekly change over 24 weeks in peak oxygen consumption and 6-minute walk distance in individuals enrolled in the Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in HFpEF trial. Our study population included 172 individuals with available plasma for cFGF23 and iFGF23 measurements. Median (25th-75th percentile) baseline cFGF23 and iFGF23 levels were 208.7 RU/mL (132.1-379.5 RU/mL) and 90.3 pg/mL (68.6-128.5 pg/mL), respectively. After adjustment for cardiovascular disease and hematologic and kidney parameters, higher cFGF23 was independently associated with a lower peak oxygen consumption at baseline. Higher iFGF23 was independently associated with shorter 6-minute walk distance at baseline. No significant associations were appreciated with the longitudinal outcomes.

CONCLUSIONS

In patients with HFpEF, higher FGF23 levels are independently associated with decreased exercise capacity at baseline.