Microvascular Dysfunction in Heart Failure with Preserved Ejection Fraction: Pathophysiology, Assessment, Prevalence and Prognosis

Coronary microvascular dysfunction and its role in heart failure with preserved ejection fraction for future prevention and treatment

Ischemic heart disease has long been established as the leading cause of heart failure, typically as a result of hemodynamically significant and obstructive coronary anatomy. Since, the role of dysfunctional coronary microvascular pathophysiologic mechanisms have also been associated with the development of congestive heart failure (CHF), most notably heart failure with preserved ejection fraction (HFpEF) although with limited clinical evidence. Conventional cardiometabolic and behavioral risk factors common to HFpEF such as diabetes mellitus (DM), obesity, hypertension, dyslipidemia, smoking, and chronic kidney disease foster a pro-inflammatory environment conducive to endothelial dysfunction and improper regulation of vasoactive substances. The impaired relaxation and increased vasoconstriction of damaged endothelium gives rise to impaired coronary blood flow and episodes of transient ischemia. Such coronary microvascular dysfunction (CMD) has its own implication on cardiovascular pathophysiologic mechanisms beyond symptomatic coronary and myocardial ischemia, and thus its own potential prevention goals and treatment targets for patients with HFpEF, where previous management had been limited. As such, we conducted a literature review to address the current landscape of data which links CMD to HFpEF. Furthermore, we considered the implications of biopsychosocial elements such as race, ethnicity, sex, gender, and the social determinants of health as they relate to the disparate health outcomes of those most at risk for CMD and HFpEF.

Heart failure and microvascular dysfunction: an in-depth review of mechanisms, diagnostic strategies, and innovative therapies

Microvascular dysfunction (MVD) is increasingly recognized as a critical contributor to the pathogenesis of heart failure (HF), particularly in heart failure with preserved ejection fraction (HFpEF) and heart failure with reduced ejection fraction (HFrEF). Coronary microvascular dysfunction (CMD) significantly impacts HFpEF by reducing coronary flow reserve and myocardial perfusion reserve, leading to adverse outcomes such as myocardial ischemia, diastolic dysfunction, and increased risk of major cardiovascular events, including atrial fibrillation. In HFrEF, microvascular impairment is linked to heightened oxidative stress, reduced nitric oxide production, and activation of the renin-angiotensin-aldosterone system, further driving disease progression and contributing to poor prognosis. Advancements in diagnostic techniques, such as positron emission tomography, cardiac magnetic resonance imaging, and biomarker analysis, improve our ability to assess CMD in heart failure patients, enabling earlier diagnosis and risk stratification. Emerging therapies, including sodium-glucose cotransporter-2 inhibitors, angiotensin receptor-neprilysin inhibitors, and endothelial-targeted interventions, enhance microvascular function and improve patient outcomes. The role of personalized medicine is becoming increasingly important, as individualized therapeutic approaches tailored to patient-specific microvascular abnormalities are essential for optimizing treatment effectiveness. This review underscores the pivotal role of MVD in HF. It highlights the urgent need for innovative therapeutic strategies and diagnostic tools to address this complex condition and improve clinical outcomes for HF patients.

Abnormal skeletal muscle and myocardial vasoreactivity manifests prior to heart failure in a diabetic cardiomyopathy rat model

Background

Microvascular dysfunction (MVD) is a recognized sign of disease in heart failure progression. Intact blood vessels exhibit abnormal vasoreactivity in early stage, subsequently deteriorating to rarefaction and reduced perfusion. In managing heart failure with preserved ejection fraction (HFpEF), earlier diagnosis is key to improving management. In this study, we applied a steady-state blood-pool magnetic resonance imaging (MRI) method to investigate if it can sensitively detect abnormal leg muscle vasoreactivity, a sign of MVD, posited to manifest before structural and functional cardiac changes emerge in a diabetes model of HFpEF.

Methods

Male and female Sprague-Dawley rats were maintained on either a high-fat, high-sugar diet or a control diet for 6 months after the induction of diabetes (n = 5 per group). Beginning at month 1 or 2 post-diabetes and every 2 months thereafter, rats underwent steady-state blood-pool MRI to assess vasoreactivity in the heart or skeletal muscle, respectively. A T1-reducing blood-pool agent was administered and the T1 relaxation time dynamically measured as animals breathed in elevated CO2 levels to modulate vessels.

Results

In male rats, the normally unresponsive heart to 10% CO2 revealed a pro-vasoconstriction response beginning at 5 months post-diabetes. Abnormal leg skeletal muscle vasoreactivity appeared even earlier, at 2 months: the usual vasodilatory response to 5% CO2 was interrupted with periods of vasoconstriction in diseased rats. In female rats, differences were observed between healthy and diseased animals only in the first 2 months post-diabetes and not later. In the heart, vasodilation to 10% CO2 seen in healthy females was abolished in diabetic females. In skeletal muscle, 5% CO2 was suboptimal in inducing reproducible vasoreactivity, but young diabetic females responded by vasodilation only.

Conclusions

Abnormal vasoreactivity presented earlier than overt functional changes in both heart and skeletal muscle in diabetic cardiomyopathy, and steady-state blood-pool MRI offered early diagnosis of microvascular dysfunction.

Low-Density Neutrophils and Neutrophil Extracellular Traps (NETs) Are New Inflammatory Players in Heart Failure

BACKGROUND

Heart failure with reduced (HFrEF) or preserved ejection fraction (HFpEF) is characterized by low-grade chronic inflammation. Circulating neutrophils regroup 2 subtypes termed high- and low-density neutrophils (HDNs and LDNs). LDNs represent less than 2% of total neutrophil under physiological conditions, but their counts increase in multiple pathologies, releasing more inflammatory cytokines and neutrophil extracellular traps (NETs). The aims of this study were to assess the differential count and role of HDNs, LDNs, and NETs-related activities in patients with heart failure (HF).

METHODS

HDNs and LDNs were isolated from human blood by density gradient and purified by fluorescence-activated cell sorting (FACS) and their counts obtained by flow cytometry. Formation of NETs (NETosis) was quantified by confocal microscopy. Circulating inflammatory and NETosis biomarkers were measured by enzyme-linked immunosorbent assay (ELISA). Neutrophil adhesion onto human extracellular matrix (hECM) was assessed by optical microscopy.

RESULTS

A total of 140 individuals were enrolled, including 33 healthy volunteers (HVs), 41 HFrEF (19 stable patients and 22 presenting acute decompensated HF [ADHF]), and 66 patients with HFpEF (36 stable patients and 30 presenting HF decompensation). HDNs and LDNs counts were significantly increased up to 39% and 2740%, respectively, in patients with HF compared with HVs. In patients with HF, the correlations among LDNs counts and circulating inflammatory (CRP, IL-6 and -8), troponin T, N-terminal prohormone of brain natriuretic peptide (NT-proBNP), and NETosis components were significant. In vitro, LDNs expressed more citrullinated histone H3 (H3Cit) and NETs and were more proadhesive, with ADHFpEF patients presenting the highest proinflammatory profile.

CONCLUSIONS

Patients with HFpEF present higher levels of circulating LDNs- and NETs-related activities, which are the highest in the context of acute HF decompensation.

Heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) accounts for nearly half of all heart failure cases and has a prevalence that is expected to rise with the growing ageing population. HFpEF is associated with significant morbidity and mortality. Specific HFpEF risk factors include age, diabetes, hypertension, obesity and atrial fibrillation. Haemodynamic contributions to HFpEF include changes in left ventricular structure, diastolic and systolic dysfunction, left atrial myopathy, pulmonary hypertension, right ventricular dysfunction, chronotropic incompetence, and vascular dysfunction. Inflammation, fibrosis, impaired nitric oxide signalling, sarcomere dysfunction, and mitochondrial and metabolic defects contribute to the cellular and molecular changes observed in HFpEF. HFpEF impacts multiple organ systems beyond the heart, including the skeletal muscle, peripheral vasculature, lungs, kidneys and brain. The diagnosis of HFpEF can be made in individuals with signs and symptoms of heart failure with abnormality in natriuretic peptide levels or evidence of cardiopulmonary congestion, facilitated by the use of HFpEF risk scores and additional imaging and testing with the exclusion of HFpEF mimics. Management includes initiation of guideline-directed medical therapy and management of comorbidities. Given the significant impact of HFpEF on quality of life, future research efforts should include a particular focus on how patients can live better with this disease.

Impact of coronary microvascular dysfunction in heart failure with preserved ejection fraction: a meta-analysis

AIMS

Several mechanisms have been identified in the aetiopathogenesis of heart failure with preserved ejection fraction (HFpEF). Among these, coronary microvascular dysfunction (CMD) may play a key pathophysiological role. We performed a systematic review and meta-analysis to investigate the prevalence, echocardiographic correlates, and prognostic implications of CMD in patients with HFpEF.

METHODS AND RESULTS

A systematic search for articles up to 1 May 2023 was performed. The primary aim was to assess the prevalence of CMD. Secondary aims were to compare key echocardiographic parameters (E/e' ratio, left atrial volume index [LAVi], and left ventricular mass index [LVMi]), clinical outcomes [death and hospitalization for heart failure (HF)], and prevalence of atrial fibrillation (AF) between patients with and without CMD. Meta-regressions according to baseline patient characteristics and study features were performed to explore potential heterogeneity sources. We identified 14 observational studies, enrolling 1138 patients with HFpEF. The overall prevalence of CMD was 58%. Compared with patients without CMD, patients with HFpEF and CMD had larger LAVi [mean difference (MD) 3.85 confidence interval (CI) 1.19-6.5, P < 0.01)], higher E/e' ratio (MD 2.76 CI 1.54-3.97; P < 0.01), higher prevalence of AF (odds ratio 1.61 CI 1.04-2.48, P = 0.03) and higher risk of death or hospitalization for HF [hazard ratio 3.19, CI 1.04-9.57, P = 0.04].

CONCLUSIONS

CMD is present in little more than half of the patients with HFpEF and is associated with echocardiographic evidence of more severe diastolic dysfunction and a higher prevalence of AF, doubling the risk of death or HF hospitalization.

The Therapy and Management of Heart Failure with Preserved Ejection Fraction: New Insights on Treatment

Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome characterised by the presence of diastolic dysfunction and elevated left ventricular filling pressure, in the setting of a left ventricular ejection fraction of at least 50%. Despite the epidemiological prevalence of HFpEF, a prompt diagnosis is challenging and many uncertainties exist. HFpEF is characterised by different phenotypes driven by various cardiac and non-cardiac comorbidities. This is probably the reason why several HFpEF clinical trials in the past did not reach strong outcomes to recommend a single therapy for this syndrome; however, this paradigm has recently changed, and the unmet clinical need for HFpEF treatment found a proper response as a result of a new class of drug, the sodium-glucose cotransporter 2 inhibitors, which beneficially act through the whole spectrum of left ventricular ejection fraction. The aim of this review was to focus on the therapeutic target of HFpEF, the role of new drugs and the potential role of new devices to manage the syndrome.

Statin administration improves vascular function in heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is characterized by impaired vascular endothelial function that may be improved by hydroxy-methylglutaryl-CoA (HMG-CoA) reductase enzyme inhibition. Thus, using a parallel, double-blind, placebo-controlled design, this study evaluated the efficacy of 30-day atorvastatin administration (10 mg daily) on peripheral vascular function and biomarkers of inflammation and oxidative stress in 16 patients with HFpEF [Statin: n = 8, 74 ± 6 yr, ejection fraction (EF) 52-73%; Placebo: n = 8, 67 ± 9 yr, EF 56-72%]. Flow-mediated dilation (FMD) and sustained-stimulus FMD (SS-FMD) during handgrip (HG) exercise, reactive hyperemia (RH), and blood flow during HG exercise were evaluated to assess conduit vessel function, microvascular function, and exercising muscle blood flow, respectively. FMD improved following statin administration (pre, 3.33 ± 2.13%; post, 5.23 ± 1.35%; P < 0.01), but was unchanged in the placebo group. Likewise, SS-FMD, quantified using the slope of changes in brachial artery diameter in response to increases in shear rate, improved following statin administration (pre: 5.31e-5 ± 3.85e-5 mm/s-1; post: 8.54e-5 ± 4.98e-5 mm/s-1; P = 0.03), with no change in the placebo group. Reactive hyperemia and exercise hyperemia responses were unchanged in both statin and placebo groups. Statin administration decreased markers of lipid peroxidation (malondialdehyde, MDA) (pre, 0.652 ± 0.095; post, 0.501 ± 0.094; P = 0.04), whereas other inflammatory and oxidative stress biomarkers were unchanged. Together, these data provide new evidence for the efficacy of low-dose statin administration to improve brachial artery endothelium-dependent vasodilation, but not microvascular function or exercising limb blood flow, in patients with HFpEF, which may be due in part to reductions in oxidative stress.NEW & NOTEWORTHY This is the first study to investigate the impact of statin administration on vascular function and exercise hyperemia in patients with heart failure with preserved ejection fraction (HFpEF). In support of our hypothesis, both conventional flow-mediated dilation (FMD) testing and brachial artery vasodilation in response to sustained elevations in shear rate during handgrip exercise increased significantly in patients with HFpEF following statin administration, beneficial effects that were accompanied by a decrease in biomarkers of oxidative damage. However, contrary to our hypothesis, reactive hyperemia and exercise hyperemia were unchanged in patients with HFpEF following statin therapy. These data provide new evidence for the efficacy of low-dose statin administration to improve brachial artery endothelium-dependent vasodilation, but not microvascular reactivity or exercising muscle blood flow in patients with HFpEF, which may be due in part to reductions in oxidative stress.

Physiology and functional significance of the coronary microcirculation: An overview of its implications in health and disease

Ischemic, Coronary Heart Disease (CHD) is a leading cause of morbidity and death worldwide.

Novel Strategies in Diagnosing Heart Failure with Preserved Ejection Fraction: A Comprehensive Literature Review

Heart failure (HF) with preserved ejection fraction (HFpEF) is a prevalent global condition affecting approximately 50% of the HF population. With the aging of the worldwide population, its incidence and prevalence are expected to rise even further. Unfortunately, until recently, no effective medications were available to reduce the high mortality and hospitalization rates associated with HFpEF, making it a significant unmet need in cardiovascular medicine. Although HFpEF is commonly defined as HF with normal ejection fraction and elevated left ventricular filling pressure, performing invasive hemodynamic assessments on every individual suspected of having HFpEF is neither feasible nor practical. Consequently, several clinical criteria and diagnostic tools have been proposed to aid in diagnosing HFpEF. Overall, these criteria and tools are designed to assist healthcare professionals in identifying and evaluating patients who may have HFpEF based on a combination of signs, symptoms, biomarkers, and non-invasive imaging findings. By employing these non-invasive diagnostic approaches, clinicians can make informed decisions regarding the best pharmacological and rehabilitation strategies for individuals with suspected HFpEF. This literature review aims to provide an overview of all currently available methods for diagnosing and monitoring this disabling condition.

Contemporary Evidence and Practice on Right Heart Catheterization in Patients with Acute or Chronic Heart Failure

Heart failure (HF) has a global prevalence of 1-2%, and the incidence around the world is growing. The prevalence increases with age, from around 1% for those aged <55 years to >10% for those aged 70 years or over. Based on studies in hospitalized patients, about 50% of patients have heart failure with reduced ejection fraction (HFrEF), and 50% have heart failure with preserved ejection fraction (HFpEF). HF is associated with high morbidity and mortality, and HF-related hospitalizations are common, costly, and impact both quality of life and prognosis. More than 5-10% of patients deteriorate into advanced HF (AdHF) with worse outcomes, up to cardiogenic shock (CS) condition. Right heart catheterization (RHC) is essential to assess hemodynamics in the diagnosis and care of patients with HF. The aim of this article is to review the evidence on RHC in various clinical scenarios of patients with HF.

Peripheral Microvascular Dysfunction in Children and Adults with Congenital Heart Disease: A Literature Review

Although there is a continually growing number of patients with congenital heart disease (CHD) due to medical and surgical advances, these patients still have a poorer prognosis compared to healthy individuals of similar age. In patients with heart failure, microvascular dysfunction (MVD) has recently emerged as a crucial modulator of disease initiation and progression. Because of the substantial pathophysiological overlap between CHD and heart failure induced by other etiologies, MVD could be important in the pathophysiology of CHD as well. MVD is believed to be a systemic disease and may be manifested in several vascular beds. This review will focus on what is currently known about MVD in the peripheral vasculature in CHD. Therefore, a search on the direct assessment of the vasodilatory capacity of the peripheral microcirculation in patients with CHD was conducted in the PubMed database. Since there is little data available and the reported studies are also very heterogeneous, peripheral MVD in CHD is not sufficiently understood to date. Its exact extent and pathophysiological relevance remain to be elucidated in further research.

Changes of left atrial morphology and function evaluated with four-dimensional automated left atrial quantification echocardiography in patients with coronary slow flow phenomenon and preserved left ventricular ejection fraction

BACKGROUND

Coronary slow flow phenomenon (CSFP) can cause left ventricular diastolic dysfunction (LVDD). In multiple studies, the left atrial (LA) strain has been reported to be an excellent parameter for assessing LVDD. The 4-dimensional automated LA quantification (4D Auto LAQ) dedicated to the LA was recently available. Our study aimed to evaluate subclinical changes in LA morphology and function with 4D Auto LAQ in patients with CSFP and preserved left ventricular ejection fraction (LVEF).

METHODS

Forty-eight patients with CSFP confirmed with coronary angiography and 46 age and gender-matched controls with normal coronary flow were enrolled. The thrombolysis in myocardial infarction frame count (TFC) method was used to record coronary blood flow velocities for each major coronary artery. LA volume, LA longitudinal and circumferential strains during each of the three LA phases (reservoir, conduit, and contraction), LA total emptying fraction (LATEF), LA active emptying fraction (LAAEF), and LA passive emptying fraction (LAPEF) were quantified with 4D Auto LAQ analysis.

RESULTS

Compared with controls, LA longitudinal reservoir strain (LASr), LA longitudinal strain during the conduit phase (LAScd), LA contraction strain (LASct), LA conduit circumferential strain (LAScd-c), LATEF, LAPEF decreased significantly in individuals with CSFP. Of the 4D- LAQ parameters, only LASr [odds ratio (OR): 0.773, P < 0.001] and LATEF [OR: 0.762, P < 0.001] were associated with CSFP in multivariate analysis. A LASr ≤23.00% can differentiate CSFP from controls [sensitivity, 66.7%; specificity, 93.5%; area under the curve (AUC), 0.823; P < 0.001]. A LASr of ≤19.00% could predict the elevation of LV filling pressure in the CSFP cohort [sensitivity, 76.9%; specificity, 74.3%; area under the curve (AUC), 0.792; P < 0.001]. LASr was the only index to demonstrate significant changes compared to controls in single-vessel CSFP. Compared to the right coronary artery (RCA) and left circumflex (LCX), TFC of the left anterior descending (LAD) artery was the only independent variable of LASr (Standardized Coefficients: -0.386, P = 0.037).

CONCLUSIONS

Impairment of LA reservoir function reflected by changes in LASr and LATEF can be seen in patients with CSFP. LASr could predict the elevation of LV filling pressure in CSFP individuals. LASr is more sensitive than LATEF in detecting LA reservoir dysfunction in single-vessel CSFP. CSFP in LAD exerts a more prominent influence on LASr than RCA or LCX.

Characterization of a robust mouse model of heart failure with preserved ejection fraction

Heart failure (HF) is a leading cause of morbidity and mortality particularly in older adults and patients with multiple metabolic comorbidities. Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome with multisystem organ dysfunction in which patients develop symptoms of HF as a result of high left ventricular (LV) diastolic pressure in the context of normal or near normal LV ejection fraction (LVEF; ≥50%). Challenges to create and reproduce a robust rodent phenotype that recapitulates the multiple comorbidities that exist in this syndrome explain the presence of various animal models that fail to satisfy all the criteria of HFpEF. Using a continuous infusion of angiotensin II and phenylephrine (ANG II/PE), we demonstrate a strong HFpEF phenotype satisfying major clinically relevant manifestations and criteria of this pathology, including exercise intolerance, pulmonary edema, concentric myocardial hypertrophy, diastolic dysfunction, histological signs of microvascular impairment, and fibrosis. Conventional echocardiographic analysis of diastolic dysfunction identified early stages of HFpEF development and speckle tracking echocardiography analysis including the left atrium (LA) identified strain abnormalities indicative of contraction-relaxation cycle impairment. Diastolic dysfunction was validated by retrograde cardiac catheterization and analysis of LV end-diastolic pressure (LVEDP). Among mice that developed HFpEF, two major subgroups were identified with predominantly perivascular fibrosis and interstitial myocardial fibrosis. In addition to major phenotypic criteria of HFpEF that were evident at early stages of this model (3 and 10 days), accompanying RNAseq data demonstrate activation of pathways associated with myocardial metabolic changes, inflammation, activation of extracellular matrix (ECM) deposition, microvascular rarefaction, and pressure- and volume-related myocardial stress.NEW & NOTEWORTHY Heart failure with preserved ejection fraction (HFpEF) is an emerging epidemic affecting up to half of patients with heart failure. Here we used a chronic angiotensin II/phenylephrine (ANG II/PE) infusion model and instituted an updated algorithm for HFpEF assessment. Given the simplicity in generating this model, it may become a useful tool for investigating pathogenic mechanisms, identification of diagnostic markers, and for drug discovery aimed at both prevention and treatment of HFpEF.

The cardio-renal-metabolic connection: a review of the evidence

Type 2 diabetes (T2D), cardiovascular disease (CVD) and chronic kidney disease (CKD), are recognized among the most disruptive public health issues of the current century. A large body of evidence from epidemiological and clinical research supports the existence of a strong interconnection between these conditions, such that the unifying term cardio-metabolic-renal (CMR) disease has been defined. This coexistence has remarkable epidemiological, pathophysiologic, and prognostic implications. The mechanisms of hyperglycemia-induced damage to the cardio-renal system are well validated, as are those that tie cardiac and renal disease together. Yet, it remains controversial how and to what extent CVD and CKD can promote metabolic dysregulation. The aim of this review is to recapitulate the epidemiology of the CMR connections; to discuss the well-established, as well as the putative and emerging mechanisms implicated in the interplay among these three entities; and to provide a pathophysiological background for an integrated therapeutic intervention aiming at interrupting this vicious crosstalks.

Positron Emission Tomography in Heart Failure: From Pathophysiology to Clinical Application

Imaging modalities are increasingly being used to evaluate the underlying pathophysiology of heart failure. Positron emission tomography (PET) is a non-invasive imaging technique that uses radioactive tracers to visualize and measure biological processes in vivo. PET imaging of the heart uses different radiopharmaceuticals to provide information on myocardial metabolism, perfusion, inflammation, fibrosis, and sympathetic nervous system activity, which are all important contributors to the development and progression of heart failure. This narrative review provides an overview of the use of PET imaging in heart failure, highlighting the different PET tracers and modalities, and discussing fields of present and future clinical application.

Impact of the Remission of Type 2 Diabetes on Cardiovascular Structure and Function, Exercise Capacity and Risk Profile: A Propensity Matched Analysis

Type 2 diabetes (T2D) confers a high risk of heart failure frequently with evidence of cardiovascular structural and functional abnormalities before symptom onset. The effects of remission of T2D on cardiovascular structure and function are unknown. The impact of the remission of T2D, beyond weight loss and glycaemia, on cardiovascular structure and function and exercise capacity is described. Adults with T2D without cardiovascular disease underwent multimodality cardiovascular imaging, cardiopulmonary exercise testing and cardiometabolic profiling. T2D remission cases (Glycated hemoglobin (HbA1c) < 6.5% without glucose-lowering therapy, ≥3 months) were propensity score matched 1:4 based on age, sex, ethnicity and time of exposure to those with active T2D (n = 100) with the nearest-neighbour method and 1:1 with non-T2D controls (n = 25). T2D remission was associated with a lower leptin-adiponectin ratio, hepatic steatosis and triglycerides, a trend towards greater exercise capacity and significantly lower minute ventilation/carbon dioxide production (VE/VCO2 slope) vs. active T2D (27.74 ± 3.95 vs. 30.52 ± 5.46, p < 0.0025). Evidence of concentric remodeling remained in T2D remission vs. controls (left ventricular mass/volume ratio 0.88 ± 0.10 vs. 0.80 ± 0.10, p < 0.025). T2D remission is associated with an improved metabolic risk profile and ventilatory response to exercise without concomitant improvements in cardiovascular structure or function. There is a requirement for continued attention to risk factor control for this important patient population.