Hemodynamic Correlates and Diagnostic Role of Cardiopulmonary Exercise Testing in Heart Failure With Preserved Ejection Fraction

Heart Failure With Preserved Ejection Fraction: A Comprehensive Review and Update of Diagnosis, Pathophysiology, Treatment, and Perioperative Implications

Almost three-quarters of all heart failure patients who are older than 65 have heart failure with preserved ejection fraction (HFpEF). The proportion and hospitalization rate of patients with HFpEF are increasing steadily relative to patients in whom heart failure occurs as result of reduced ejection fraction. The predominance of the HFpEF phenotype most likely is explained by the prevalence of medical conditions associated with an aging population. A multitude of age-related, medical, and lifestyle risk factors for HFpEF have been identified as potential causes for the sustained low-grade proinflammatory state that accelerates disease progression. Profound left ventricular (LV) systolic and diastolic stiffening, elevated LV filling pressures, reduced arterial compliance, left atrial hypertension, pulmonary venous congestion, and microvascular dysfunction characterize HFpEF, but pulmonary arterial hypertension, right ventricular dilation and dysfunction, and atrial fibrillation also frequently occur. These cardiovascular features make patients with HFpEF exquisitely sensitive to the development of hypotension in response to acute declines in LV preload or afterload that may occur during or after surgery. With the exception of symptom mitigation, lifestyle modifications, and rigorous control of comorbid conditions, few long-term treatment options exist for these unfortunate individuals. Patients with HFpEF present for surgery on a regular basis, and anesthesiologists need to be familiar with this heterogeneous and complex clinical syndrome to provide successful care. In this article, the authors review the diagnosis, pathophysiology, and treatment of HFpEF and also discuss its perioperative implications.

Clinical, Demographic, and Imaging Correlates of Anemia in Heart Failure With Preserved Ejection Fraction (from the RELAX Trial)

Anemia is a commonly occurring comorbidity among patients of heart failure with preserved ejection fraction (HFpEF) but limited data exists on the cardiovascular phenotype of anemia in HFpEF. We sought to characterize the clinical features, exercise capacity, and outcomes in patients with HFpEF to elucidate the phenotype and pathophysiology of anemia in HFpEF. Post hoc analyses of participants enrolled in the RELAX (Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in Diastolic Heart Failure) trial was performed. Anemia was defined as hemoglobin <13 g/dL in men and <12 g/dL in women. Multivariate adjusted regression modeling was done to assess for differences in peak oxygen uptake. Adjusted hazard ratios were generated to assess difference in hospitalization events using a Cox proportional hazards model. Anemic HFpEF patients were more likely to be older, male, and have worse renal function (p <0.05 for all). N-terminal pro-B-type natriuretic peptide, troponin I, pro-collagen III N-terminal peptide, C-telopeptide for type I collagen, uric acid, cystatin-c, and galectin-3 (p <0.05 for all) levels were higher in anemic HFpEF patients. In adjusted models, anemic HFpEF patients had worse exercise capacity (peak oxygen uptake: 11.3 vs 12.1 mL/kg/min; p = 0.004). The hazard for cardiac or renal cause of hospitalization in those with anemia was 2.0 (95% confidence interval: 0.9 to 4.3). Anemic HFpEF patients have worse exercise capacity and are more likely to be hospitalized. A better understanding of the physiologic phenotypes of HFpEF patients may allow for greater personalization of treatment and prognostication in HFpEF patients.

Performance and Interpretation of Invasive Hemodynamic Exercise Testing

Exertional dyspnea is a common complaint for patients seen in pulmonary, cardiac, and general medicine clinics, and elucidating the cause is often challenging, particularly when physical examination, echocardiography, radiography, and pulmonary function test results are inconclusive. Invasive cardiopulmonary exercise testing has emerged as the gold standard test to define causes of dyspnea and exertional limitation in this population. In this review, we describe the methods for performing and interpreting invasive cardiopulmonary exercise testing, with particular attention to the hemodynamic and blood sampling data as they apply to patients being evaluated for heart failure and pulmonary hypertension.

Early Stages of Obesity-related Heart Failure Are Associated with Natriuretic Peptide Deficiency and an Overall Lack of Neurohormonal Activation: The Copenhagen Heart Failure Risk Study

Objective

This study evaluated the associations between the natriuretic peptide activity and the neurohormonal response in non-obese and obese outpatients with and without heart failure (HF).

Background

Obesity-related HF may be a distinct subtype of HF. Obesity is associated with lower plasma concentrations of natriuretic peptides. The associations between obesity and neurohormonal activation estimated by mid-regional pro-adrenomedullin (MR-proADM) and copeptin in patients with HF is not elucidated.

Methods

This prospective cohort-study included 392 outpatients ≥60years, plus ≥1 risk-factor(-s) for HF (hypertension, ischemic heart disease, atrial fibrillation, diabetes, chronic kidney disease), and without known HF. Patients were categorized 'non-obese' BMI = 18.5-29.9 kg/m2 (n = 273) and 'obese' BMI ≥ 30 kg/m2 (n = 119). The diagnosis of HF required signs, symptoms, and abnormal echocardiography. NT-proBNP, MR-proANP, MR-proADM, and copeptin were analyzed.

Results

Obese patients were younger, had a higher prevalence of diabetes and chronic kidney disease, but a lower prevalence of atrial fibrillation. A total of 39 (14.3%) non-obese and 26 (21.8%) obese patients were diagnosed with HF. In obese patients, HF was not associated with higher plasma concentrations of NT-proBNP (Estimate: 0.063; 95%CI: -0.037-1.300; P = 0.064), MR-proANP (Estimate: 0.207; 95%CI: -0.101-0.515; P = 0.187), MR-proADM (Estimate: 0.112; 95%CI: -0.047-0.271; P = 0.168), or copeptin (Estimate: 0.093; 95%CI: -0.333-0.518; P = 0.669). Additionally, obese patients with HF had lower plasma concentrations of NT-proBNP (Estimate: -0.998; 95%CI: -1.778-0.218; P = 0.012), and MR-proANP (Estimate: -0.488; 95%CI: -0.845-0.132; P = 0.007) compared to non-obese patients with HF, whereas plasma concentrations of MR-proADM (Estimate: 0.066; 95%CI: -0.119-0.250; P = 0.484) and copeptin (Estimate: 0.140; 95%CI: -0.354-0.633; P = 0.578) were comparable.

Conclusions

Patients with obesity-related HF have natriuretic peptide deficiency and lack of increased plasma concentrations of MR-proADM and copeptin suggesting that patients with obesity-related HF have a blunted overall neurohormonal activity.

Peripheral Determinants of Oxygen Utilization in Heart Failure With Preserved Ejection Fraction: Central Role of Adiposity

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ΔAVo₂ during exercise is a complex metric that incorporates into its calculation skeletal muscle blood flow and DmO₂ across the skeletal muscle capillary membrane.

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Although ΔAVo₂ was reduced in patients with HFpEF during both systemic and local (forearm) exercise, there was no difference in forearm DmO₂ among subjects with HFpEF, those with hypertension, and healthy control subjects; therefore, abnormalities in forearm DmO₂ cannot explain the reduced forearm ΔAVo₂ seen in subjects with HFpEF.

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Local forearm exercise performance predicted about one-third of the variability in systemic aerobic capacity, demonstrating that peripheral factors are important in determining whole-body exercise tolerance.

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Degree of adiposity strongly correlated with ΔAVo₂ during both local and whole-body exercise, suggesting that adipose tissue may play an active role in limiting exercise capacity in subjects with HFpEF.

The aim of this study was to determine the arteriovenous oxygen content difference (ΔAVo₂) in adult subjects with and without heart failure with preserved ejection fraction (HFpEF) during systemic and forearm exercise. Subjects with HFpEF had reduced ΔAVo₂. Forearm diffusional conductance for oxygen, a lumped conductance parameter that incorporates all impediments to the movement of oxygen from red blood cells in skeletal muscle capillaries into the mitochondria within myocytes, was estimated. Forearm diffusional conductance for oxygen was not different among adults with HFpEF, those with hypertension, and healthy control subjects; therefore, diffusional conductance cannot explain the reduced forearm ΔAVo₂. Instead, adiposity was strongly associated with ΔAVo₂, suggesting an active role for adipose tissue in reducing exercise capacity in patients with HFpEF.

How to diagnose heart failure with preserved ejection fraction: the HFA-PEFF diagnostic algorithm: a consensus recommendation from the Heart Failure Association (HFA) of the European Society of Cardiology (ESC)

Making a firm diagnosis of chronic heart failure with preserved ejection fraction (HFpEF) remains a challenge. We recommend a new stepwise diagnostic process, the 'HFA-PEFF diagnostic algorithm'. Step 1 (P=Pre-test assessment) is typically performed in the ambulatory setting and includes assessment for heart failure symptoms and signs, typical clinical demographics (obesity, hypertension, diabetes mellitus, elderly, atrial fibrillation), and diagnostic laboratory tests, electrocardiogram, and echocardiography. In the absence of overt non-cardiac causes of breathlessness, HFpEF can be suspected if there is a normal left ventricular (LV) ejection fraction, no significant heart valve disease or cardiac ischaemia, and at least one typical risk factor. Elevated natriuretic peptides support, but normal levels do not exclude a diagnosis of HFpEF. The second step (E: Echocardiography and Natriuretic Peptide Score) requires comprehensive echocardiography and is typically performed by a cardiologist. Measures include mitral annular early diastolic velocity (e'), LV filling pressure estimated using E/e', left atrial volume index, LV mass index, LV relative wall thickness, tricuspid regurgitation velocity, LV global longitudinal systolic strain, and serum natriuretic peptide levels. Major (2 points) and Minor (1 point) criteria were defined from these measures. A score ≥5 points implies definite HFpEF; ≤1 point makes HFpEF unlikely. An intermediate score (2-4 points) implies diagnostic uncertainty, in which case Step 3 (F₁ : Functional testing) is recommended with echocardiographic or invasive haemodynamic exercise stress tests. Step 4 (F₂ : Final aetiology) is recommended to establish a possible specific cause of HFpEF or alternative explanations. Further research is needed for a better classification of HFpEF.

Comprehensive Diagnostic Evaluation of Cardiovascular Physiology in Patients With Pulmonary Vascular Disease: Insights From the PVDOMICS Program

BACKGROUND

Invasive hemodynamic evaluation through right heart catheterization plays an essential role in the diagnosis, categorization, and risk stratification of patients with pulmonary hypertension.

METHODS

Subjects enrolled in the PVDOMICS (Redefining Pulmonary Hypertension through Pulmonary Vascular Disease Phenomics) program undergo an extensive invasive hemodynamic evaluation that includes repeated measurements at rest and during several provocative physiological challenges. It is a National Institutes of Health/National Heart, Lung, and Blood Institute initiative to reclassify pulmonary hypertension groups based on clustered phenotypic and phenomic characteristics. At a subset of centers, participants also undergo an invasive cardiopulmonary exercise test to assess changes in hemodynamics and gas exchange during exercise.

CONCLUSIONS

When coupled with other physiological testing and blood -omic analyses involved in the PVDOMICS study, the comprehensive right heart catheterization protocol described here holds promise to clarify the diagnosis and clustering of pulmonary hypertension patients into cohorts beyond the traditional 5 World Symposium on Pulmonary Hypertension groups. This article will describe the methods applied for invasive hemodynamic characterization in the PVDOMICS program. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02980887.

Hemodynamic assessment in heart failure

Hemodynamics play a central role in the pathophysiology of heart failure (HF), yet their proper assessment and optimization remains challenging. Heart failure is defined as the inability of the heart to deliver adequate perfusion (cardiac output) to the body at rest or exercise, or to require an elevation in cardiac filling pressures in order to do this. This bedrock definition is important because it relies on measurable quantities (filling pressures and output) that are readily assessed in the cardiac catheterization laboratory. Here we present three cases to illustrate how better understanding of the determinants of cardiac output and stroke volume: preload, afterload, contractility, and lusitropy, as well as the determinants of congestion (high filling pressures) may be used to guide optimization of hemodynamic status. The goal is that the readers will be able to think more critically when evaluating the hemodynamics of their patient in HF and recognize the complex interplay that determines the complex balance between cardiac ejection and filling capabilities, and how this alters symptoms and outcomes for patients with HF. KEY POINTS: Careful assessment of hemodynamics in the catheterization laboratory allows for actionable insight to a patient's volume status, cardiac function and can help prognosticate outcomes. Exercise hemodynamics in heart failure is a powerful tool to better understand the cause of symptoms and predict outcomes. Clinicians should aim to decrease biventricular filling pressures to normal values to improve morbidity and reduce risk for readmission. In patients with heart failure and reduced ejection fraction, clinicians should aim to decrease afterload as much as can be tolerated by the renal function and patient's symptoms. Low cardiac output can often be improved by optimizing preload and afterload rather than initiating inotropes, which should be reserved until needed. In advanced heart failure, the right heart function becomes a key determinant of symptoms and outcomes.

Haemodynamic and metabolic phenotyping of hypertensive patients with and without heart failure by combining cardiopulmonary and echocardiographic stress test

AIM

We combined cardiopulmonary exercise test (CPET) and exercise stress echocardiography (ESE) to identify early haemodynamic and metabolic alterations in patients with hypertension (HT) with and without heart failure with preserved ejection fraction (HFpEF).

METHODS AND RESULTS

Fifty stable HFpEF-HT outpatients (mean age 68 ± 14 years) on optimal medical therapy, 63 well-controlled HT subjects (mean age 63 ± 11 years) and 32 age and sex-matched healthy controls (mean age 59 ± 15 years) underwent a symptom-limited graded ramp bicycle CPET-ESE. The acquisition protocol included left ventricular cardiac output, global longitudinal strain, E/e', peak oxygen consumption (VO₂ ), non-invasive arterial-venous oxygen content difference (AVO₂ diff) and lung ultrasound B-lines. There was a decline in peak VO₂ from controls (24.4 ± 3 mL/min/kg) to HFpEF-HT (15.2 ± 2 mL/min/kg), passing through HT (18.7 ± 2 mL/min/kg; P < 0.0001). HFpEF-HT displayed a lower peak cardiac output (9.8 ± 0.9 L/min) compared to HT (12.6 ± 1.0 L/min; P = 0.02) and controls (13.3 ± 1.0 L/min; P = 0.01). Peak AVO₂ diff was reduced in HFpEF-HT and HT (13.3 ± 2 and 13.5 ± 2 mL/dL vs. controls: 16.9 ± 2 mL/dL; P < 0.0001). A different left ventricular contractility was observed among groups, expressed as low-load global longitudinal strain (-16.8 ± 5% in HFpEF-HT, -18.2 ± 3% in HT, and 20.9 ± 3% in controls; P < 0.0001), and distribution of E/e' and B-lines [HFpEF-HT: 13.7 ± 3 and 16, interquartile range (IQR) 10-22; HT: 9.5 ± 2 and 8, IQR 4-10; controls: 6.2 ± 2 and 0, IQR 0-2; P < 0.0001].

CONCLUSIONS

Reduced peak VO₂ values in HT with and without HFpEF may be the result of decreased AVO₂ diff. CPET-ESE can also identify mild signs of left ventricular systo-diastolic dysfunction and pulmonary congestion, promoting advances in personalized therapy.

Diastolic Dysfunction and Heart Failure With Preserved Ejection Fraction: Understanding Mechanisms by Using Noninvasive Methods

Research in the last decade has substantially advanced our understanding of the pathophysiology of heart failure with preserved ejection fraction (HFpEF). However, treatment options remain limited as clinical trials have largely failed to identify effective therapies. Part of this failure may be related to mechanistic heterogeneity. It is speculated that categorizing HFpEF patients based upon underlying pathophysiological phenotypes may represent the key next step in delivering the right therapies to the right patients. Echocardiography may provide valuable insight into both the pathophysiology and underlying phenotypes in HFpEF. Echocardiography also plays a key role in the evaluation of patients with unexplained dyspnea, where HFpEF is suspected but the diagnosis remains unknown. The combination of the E/e' ratio and right ventricular systolic pressure has recently been shown to add independent value to the diagnostic evaluation of patients suspected of having HFpEF. Finally, echocardiography enables identification of the different causes that mimic HFpEF but are treated differently, such as valvular heart disease, pericardial constriction, and high-output heart failure or infiltrative myopathies such as cardiac amyloid. This review summarizes the current understanding of the pathophysiology and phenotyping of HFpEF with particular attention to the role of echocardiography in this context.

Stress Echocardiography-Derived E/e' Predicts Abnormal Exercise Hemodynamics in Heart Failure With Preserved Ejection Fraction

Background

The correlation between echocardiographic parameters and hemodynamics data in patients with heart failure with preserved ejection fraction (HFpEF) is unclear. It is important to find a non-invasive echocardiographic parameter for predicting exercise pulmonary capillary wedge pressure (PCWP).

Aim

This study sought to determine the correlation between echocardiographic parameters and hemodynamics data at rest and during exercise in HFpEF patients.

Methods and Results

This study was a cross-sectional cohort exploratory analysis of baseline data from the ILO-HOPE trial. A total of 34 HFpEF patients were enrolled. The average age was 70 ± 12 years, and most (74%) were women. The patients underwent invasive cardiac catheterization and expired gas analysis at rest and during exercise. Echocardiography including tissue Doppler imaging was performed, and global longitudinal strain and other novel diastolic function indexes were analyzed at rest and during exercise. At rest, no significant correlation was noted between resting PCWP and echocardiographic parameters. However, a significant correlation was observed between post-exercise PCWP and stress E/e′ (septal, lateral, and mean) ratio (p = 0.003, 0.031, 0.012). Moreover, post-exercise ΔPCWP showed a good correlation with stress E/e′ (septal, lateral, and mean; all p ≤ 0.001) and global longitudinal strain (GLS) during exercise (p = 0.03). After multivariate regression analysis with adjustment for possible confounding factors including age and sex, there was still a significant correlation between post-exercise ΔPCWP and E/e′ (r = 0.62, p < 0.001 for E/e′_mean).

Conclusion

Only stress echocardiography derived tissue Doppler E/e′ ratio is closely correlated with abnormal exercise hemodynamics (PCWP and post-exercise ΔPCWP) in HFpEF. This echocardiographic marker is substantially more sensitive than other novel echocardiographic parameters during exercise, and may have significant diagnostic utility for ambulatory HFpEF patients with dyspnea.

Clinical Trial Registration

https://www.clinicaltrials.gov, identifier NCT03620526.

The β-Adrenergic Agonist Albuterol Improves Pulmonary Vascular Reserve in Heart Failure With Preserved Ejection Fraction

RATIONALE

Pulmonary vascular resistance fails to decrease appropriately during exercise in patients with heart failure with preserved ejection fraction (HFpEF). Interventions that enhance pulmonary vasodilation might be beneficial in this cohort but could also worsen left atrial hypertension, exacerbating lung congestion. Intravenous β-agonists reduce pulmonary vascular resistance but are not suitable for chronic use.

OBJECTIVE

We hypothesized that the inhaled β-adrenergic agonist albuterol would improve pulmonary vasodilation during exercise in patients with HFpEF, without increasing left heart filling pressures.

METHODS AND RESULTS

We performed a randomized, double-blind, placebo-controlled trial testing the effects of inhaled albuterol on resting and exercise hemodynamics in subjects with HFpEF using high-fidelity micromanometer catheters and expired gas analysis. The primary end point was pulmonary vascular resistance during exercise. Subjects with HFpEF (n=30) underwent resting and exercise hemodynamic assessment and were then randomized 1:1 to inhaled, nebulized albuterol or placebo. Rest and exercise hemodynamic testing was then repeated. Albuterol improved the primary end point of exercise pulmonary vascular resistance as compared with placebo (-0.6±0.5 versus +0.1±0.7 WU; P=0.003). Albuterol enhanced cardiac output reserve and right ventricular pulmonary artery coupling, reduced right atrial and pulmonary artery pressures, improved pulmonary artery compliance, and enhanced left ventricular transmural distending pressure (all P <0.01), with no increase in pulmonary capillary hydrostatic pressures.

CONCLUSIONS

Albuterol improves pulmonary vascular reserve in patients with HFpEF without worsening left heart congestion. Further study is warranted to evaluate the chronic efficacy of β-agonists in HFpEF and other forms of pulmonary hypertension.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov . Unique identifier: NCT02885636.

H2FPEF Score for the Prediction of Exercise Intolerance and Abnormal Hemodynamics in Japanese - Evaluation by Exercise Stress Echocardiography Combined With Cardiopulmonary Exercise Testing

BACKGROUND

Both the H₂FPEF-score and nomogram-score, which consist of simple clinical parameters, can assist in diagnosing "early" heart failure with preserved ejection fraction (HFpEF) and only exertional dyspnea, but their these usefulness in Japanese remains unclear. We sought to investigate the correlation between these scores and exercise response, including the peak oxygen uptake (V̇O₂), the pulmonary artery systolic pressure (PASP), the ratio of early diastolic transmitral flow velocity to early diastolic mitral annular velocity (E/e') and stroke volume (SV) using exercise stress echocardiography (ESE) combined with cardiopulmonary exercise testing (CPET).Methods and Results:In this single-center, retrospective cross-sectional study the H₂FPEF-score and nomogram-score were calculated in a total of 139 patients who underwent ESE combined with CPET. The scores correlated with peak V̇O₂(r=-0.48, r=-0.44), PASP (r=0.23, r=0.29) and SV (r=-0.32, r=-0.19) at peak exercise. The nomogram-score correlated with E/e' (r=0.24). The prevalence of exercise intolerance (percent predicted peak V̇O₂<75% and <50%) increased as the H₂FPEF-score increased and reached 88.9% and 22.2% among the patients with high H₂FPEF-score (6-9 points).

CONCLUSIONS

The H₂FPEF-score may be useful as the initial step to diagnosing 'early' HFpEF. The nomogram-score may be more useful in Japanese because of its more universal association with exercise response than the H₂FPEF-score.

Hemodynamic Effects of Weight Loss in Obesity: A Systematic Review and Meta-Analysis

OBJECTIVES

The authors aimed to explore whether weight loss may improve central hemodynamics in obesity.

BACKGROUND

Hemodynamic abnormalities in obese heart failure with preserved ejection fraction patients are correlated with the amount of excess body mass, suggesting a possible causal relationship.

METHODS

Relevant databases were systematically searched from inception to May 2018, without language restriction. Studies reporting invasive hemodynamic measures before and following therapeutic weight loss interventions in patients with obesity but no clinically overt heart failure were extracted.

RESULTS

A total of 9 studies were identified, providing data for 110 patients. Six studies tested dietary intervention and 3 studies tested bariatric surgery. Over a median duration of 9.7 months (range 0.75 to 23.0 months), a median weight loss of 43 kg (range 10 to 58 kg) was associated with significant reductions in heart rate (-9 beats/min, 95% confidence interval [CI]: -12 to -6; p < 0.001), mean arterial pressure (-7 mm Hg, 95% CI: -11 to -3; p < 0.001), and resting oxygen consumption (-85 ml/min, 95% CI: -111 to -60; p < 0.001). Central cardiac hemodynamics improved, manifested by reductions in pulmonary capillary wedge pressure (-3 mm Hg, 95% CI: -5 to -1; p < 0.001) and mean pulmonary artery pressure (-5 mm Hg, 95% CI: -8 to -2; p = 0.001). Exercise hemodynamics were assessed in a subset of patients (n = 49) in which there was significant reduction in exercise pulmonary artery pressure (p = 0.02).

CONCLUSIONS

Therapeutic weight loss in obese patients without HF is associated with favorable hemodynamic effects. Randomized controlled trials evaluating strategies for weight loss in obese patients with heart failure such as the obese phenotype of heart failure with preserved ejection fraction are needed.

Heart Failure With Preserved Ejection Fraction In Perspective

Approximately half of the patients with signs and symptoms of heart failure have a left ventricular ejection fraction that is not markedly abnormal. Despite the historically initial surprise, heightened risks for heart failure specific major adverse events occur across the broad range of ejection fraction, including normal. The recognition of the magnitude of the problem of heart failure with preserved ejection fraction in the past 20 years has spurred an explosion of clinical investigation and growing intensity of informative outcome trials. This article addresses the historic development of this component of the heart failure syndrome, including the epidemiology, pathophysiology, and existing and planned therapeutic studies. Looking forward, more specific phenotyping and even genotyping of subpopulations should lead to improvements in outcomes from future trials.

Pulmonary vascular disease in the setting of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is defined as clinical features of heart failure, ideally with biomarker evidence such as elevated plasma natriuretic peptide levels, in the setting of an ejection fraction (EF) greater than 50% and imaging evidence of diastolic left ventricular dysfunction [1,2]. In the absence of cardiac imaging or invasive hemodynamics, this is a clinical syndrome that is often indistinguishable from heart failure with reduced ejection fraction (HFrEF). HFpEF and HFrEF present with a cadre of comparable signs and symptoms including jugular venous distention, pulmonary rales on auscultation, breathlessness, orthopnea, exercise intolerance, exertional dyspnea, fatigue and peripheral edema. HFpEF accounts for at least half of all diagnoses of heart failure [1,2]. Pulmonary hypertension (PH) is a common complication of HFpEF that is linked to worse disease morbidity and mortality. In fact, mortality has been linked to increases in the intrinsic pulmonary vascular resistance in the setting of increased left ventricular end diastolic pressure, characterized hemodynamically by rises in the transpulmonary pressure gradient, pulmonary vascular resistance or diastolic pressure gradient. Despite being the most common form of PH, there are no approved therapies for the treatment of PH secondary to HFpEF. This review will summarize the hemodynamic classifications of PH in the setting of HFpEF, mechanisms of disease, the potential contribution of pulmonary vascular disease to poor outcomes in patients with HFpEF, and new approaches to therapy.

Does Left Ventricular Systolic Function Matter? Treating Atrial Fibrillation in HFrEF Versus HFpEF

Atrial fibrillation (AF) and heart failure (HF) pose international health care challenges that contribute significantly to hospitalizations, morbidity, mortality, and significant health care costs. Both AF and HF contribute to the development of each other and both are associated with a worsened prognosis when they occur together. Assessment of systolic function via transthoracic echocardiography is essential in the investigation of the AF patient. Clinical and echocardiographic assessment may classify AF patients with HF into HF with reduced ejection fraction (HF-rEF) and HF with preserved ejection fraction (HF-pEF). Such classification can assist in numerous important management decisions in AF.

Exercise Ventilatory Efficiency in Older and Younger Heart Failure Patients With Preserved Ejection Fraction

BACKGROUND

Patients with heart failure with preserved ejection fraction (HFpEF) exhibit pulmonary abnormalities, but the studies to date have reported wide variability in the ventilatory equivalent for carbon dioxide (V̇_E/V̇CO₂) slope. It is possible that aging may contribute to that variability. We sought to compare ventilatory efficiency and its components in older and younger HFpEF patients during exercise.

METHODS AND RESULTS

Eighteen older (O; 80 ± 4 y) and 19 younger (Y; 59 ± 7 y) HFpEF patients performed cardiopulmonary exercise testing to volitional fatigue. Measurements of arterial blood gases were used to derive V_D/V_T, dead space ventilation, and alveolar ventilation. V̇_E/V̇CO₂ slope was greater in older compared with younger HFpEF patients (O 36 ± 7vs Y 31 ± 7; P = .04). At peak exercise, older HFpEF exhibited greater V_D/V_T compared with younger HFpEF (O 0.37 ± 0.10vs Y 0.28 ± 0.10; P < .01), whereas PaCO₂ was not different between groups (P = .58). V̇_E and alveolar ventilation were similar (P > .23), but dead space ventilation was greater in older compared with younger HFpEF at peak exercise (P = .04).

CONCLUSIONS

Older HFpEF patients exhibit greater ventilatory inefficiency resulting from elevated physiologic dead space during peak exercise compared with younger HFpEF patients. These results suggest that aging can worsen the pathophysiologic mechanisms underlying ventilatory efficiency during exercise in HFpEF.

The Role of Echocardiography in Heart Failure with Preserved Ejection Fraction: What Do We Want from Imaging?

Noninvasive imaging, particularly echocardiography, plays a central role in the evaluation for heart failure with preserved ejection fraction (HFpEF). Echocardiography helps to rule in HFpEF among patients with unexplained dyspnea when the diagnosis is uncertain. In established HFpEF, echocardiography provides important insights into pathophysiology and phenotyping, such as isolated left ventricular diastolic dysfunction, left atrial dysfunction, abnormal right ventricular-pulmonary artery coupling, ischemia, or obesity phenotypes. In addition, imaging enables risk stratification for HFpEF. This article provides a critical appraisal of the role of echocardiography in the diagnosis and evaluation of HFpEF.

Insights into the pulmonary vascular complications of heart failure with preserved ejection fraction

Pulmonary hypertension in the setting of heart failure with preserved ejection fraction (PH-HFpEF) is a growing public health problem that is increasing in prevalence. While PH-HFpEF is defined by a high mean pulmonary artery pressure, high left ventricular end-diastolic pressure and a normal ejection fraction, some HFpEF patients develop PH in the presence of pulmonary vascular remodelling with a high transpulmonary pressure gradient or pulmonary vascular resistance. Ageing, increased left atrial pressure and stiffness, mitral regurgitation, as well as features of metabolic syndrome, which include obesity, diabetes and hypertension, are recognized as risk factors for PH-HFpEF. Qualitative studies have documented that patients with PH-HFpEF develop more severe symptoms than those with HFpEF and are associated with more significant exercise intolerance, frequent hospitalizations, right heart failure and reduced survival. Currently, there are no effective therapies for PH-HFpEF, although a number of candidate drugs are being evaluated, including soluble guanylate cyclase stimulators, phosphodiesterase type 5 inhibitors, sodium nitrite and endothelin receptor antagonists. In this review we attempt to provide an updated overview of recent findings pertaining to the pulmonary vascular complications in HFpEF in terms of clinical definitions, epidemiology and pathophysiology. Mechanisms leading to pulmonary vascular remodelling in HFpEF, a summary of pre-clinical models of HFpEF and PH-HFpEF, and new candidate therapeutic strategies for the treatment of PH-HFpEF are summarized.

Effect of Inorganic Nitrite vs Placebo on Exercise Capacity Among Patients With Heart Failure With Preserved Ejection Fraction: The INDIE-HFpEF Randomized Clinical Trial

IMPORTANCE

There are few effective treatments for heart failure with preserved ejection fraction (HFpEF). Short-term administration of inorganic nitrite or nitrate preparations has been shown to enhance nitric oxide signaling, which may improve aerobic capacity in HFpEF.

OBJECTIVE

To determine the effect of 4 weeks' administration of inhaled, nebulized inorganic nitrite on exercise capacity in HFpEF.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter, double-blind, placebo-controlled, 2-treatment, crossover trial of 105 patients with HFpEF. Participants were enrolled from July 22, 2016, to September 12, 2017, at 17 US sites, with final date of follow-up of January 2, 2018.

INTERVENTIONS

Inorganic nitrite or placebo administered via micronebulizer device. During each 6-week phase of the crossover study, participants received no study drug for 2 weeks (baseline/washout) followed by study drug (nitrite or placebo) at 46 mg 3 times a day for 1 week followed by 80 mg 3 times a day for 3 weeks.

MAIN OUTCOMES AND MEASURES

The primary end point was peak oxygen consumption (mL/kg/min). Secondary end points included daily activity levels assessed by accelerometry, health status as assessed by the Kansas City Cardiomyopathy Questionnaire (score range, 0-100, with higher scores reflecting better quality of life), functional class, cardiac filling pressures assessed by echocardiography, N-terminal fragment of the prohormone brain natriuretic peptide levels, other exercise indices, adverse events, and tolerability. Outcomes were assessed after treatment for 4 weeks.

RESULTS

Among 105 patients who were randomized (median age, 68 years; 56% women), 98 (93%) completed the trial. During the nitrite phase, there was no significant difference in mean peak oxygen consumption as compared with the placebo phase (13.5 vs 13.7 mL/kg/min; difference, -0.20 [95% CI, -0.56 to 0.16]; P = .27). There were no significant between-treatment phase differences in daily activity levels (5497 vs 5503 accelerometry units; difference, -15 [95% CI, -264 to 234]; P = .91), Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (62.6 vs 61.9; difference, 1.1 [95% CI, -1.4 to 3.5]; P = .39), functional class (2.5 vs 2.5; difference, 0.1 [95% CI, -0.1 to 0.2]; P = .43), echocardiographic E/e' ratio (16.4 vs 16.6; difference, 0.1 [95% CI, -1.2 to 1.3]; P = .93), or N-terminal fragment of the prohormone brain natriuretic peptide levels (520 vs 533 pg/mL; difference, 11 [95% CI, -53 to 75]; P = .74). Worsening heart failure occurred in 3 participants (2.9%) during the nitrite phase and 8 (7.6%) during the placebo phase.

CONCLUSIONS AND RELEVANCE

Among patients with HFpEF, administration of inhaled inorganic nitrite for 4 weeks, compared with placebo, did not result in significant improvement in exercise capacity.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02742129.