Coronary microvascular dysfunction and future risk of heart failure with preserved ejection fraction

Rationale and design of the women's ischemia syndrome evaluation mechanisms of coronary microvascular dysfunction leading to preheart failure with preserved ejection fraction (WISE Pre-HFPEF)

BACKGROUND

There is increasing recognition that the pathophysiology of coronary microvascular dysfunction (CMD) plays a pivotal role in the development of heart failure with preserved ejection fraction (HFpEF). However, the mechanisms underlying this role are not known.

STUDY DESIGN AND METHODS

The Women's Ischemia Syndrome Evaluation Mechanisms of Coronary Microvascular Dysfunction Leading to Pre-Heart Failure With Preserved Ejection Fraction (WISE Pre-HFpEF) is a prospective cohort study enrolling 180 women and men undergoing clinically indicated invasive coronary angiography for suspected ischemia with no obstructive coronary artery disease. The study aims to investigate (1) CMD-related ischemia contribution to myocellular damage and impaired left ventricular (LV) relaxation as determined invasively by ultra-high sensitivity cardiac troponin I (u-hs-cTnI) measurements in the coronary sinus/great cardiac vein and LV pressure-volume loops, respectively, during provocative stress testing with isometric handgrip, and (2) CMD-related ischemic myocellular damage contribution to LV diastolic dysfunction progression as assessed using cardiac magnetic resonance imaging obtained at enrollment and 1-2 years later, along with prospectively repeated ambulatory u-hs-cTnI measurements.

CONCLUSIONS

The WISE pre-HFpEF study is designed to investigate whether ischemic myocardial damage secondary to CMD contributes to the progression of LV diastolic dysfunction. The findings from this study will provide new understanding of the role of CMD in HFpEF development as well as the potential benefits of CMD-directed therapies for the prevention and treatment of HFpEF.

TRIAL REGISTRATION

ClilicalTrial.gov, NCT03876223.

The association of coronary microvascular dysfunction and cardiac maladaptation with clinical outcomes in heart failure with preserved ejection fraction: A prospective dynamic SPECT study

BACKGROUND

Accumulating evidences have suggested a pathophysiological link between coronary microvascular dysfunction (CMD) and heart failure with preserved ejection fraction (HFpEF). The clinical relevance and prognostic impact of myocardial blood flow (MBF) using single-photon emission computed tomography (SPECT) among HFpEF patients remain unexplored clearly.

METHODS

Fifty-five patients with HFpEF and 48 controls were prospectively enrolled. All underwent dynamic myocardial perfusion imaging with (99 m) Tc-sestamibi at rest and a stress test at peak with dipyridamole. MBF and myocardial flow reserve (MFR) parameters were obtained after perfusion and further related to cardiac structural and advanced functional strain measures using echocardiography and clinical outcomes.

RESULTS

CMD (defined as global MFR <2.5) was more prevalent in HFpEF than in control (71 % vs 16.7 %). Patients with HFpEF had worse longitudinal strain indices, lower post-stress MBF (2.37 ± 0.78 vs. 3.30 ± 0.94 ml/min/g, p < 0.001), higher global rest MBF (1.11 ± 0.55 vs. 0.89 ± 0.19 ml/min/g, p = 0.008), and lower global MFR (2.34 ± 0.84 vs. 3.68 ± 1.04, p < 0.001) than the controls. These results were similar for the regional MFRs in the vascular-based analysis. Lower MFR correlated with more impaired left ventricular, left atrial, and right ventricular strain measures (r = -0.44, 0.38, and 0.27, respectively, all p < 0.05). Patients with HFpEF and CMD had increased risks of all-cause mortality and hospitalization compared with those without HFpEF nor CMD (adjusted hazard: 6.42, 95 % CI: 1.40-29.43, p = 0.017).

CONCLUSIONS

CMD by dynamic SPECT is frequently observed among patients with HFpEF and correlated with more impaired overall cardiac mechanics. HFpEF with comorbid CMD had worse clinical outcome.

Single nucleotide polymorphisms: Implications in the early diagnosis and targeted intervention of coronary microvascular dysfunction

Coronary microvascular dysfunction (CMD) is a clinical syndrome of myocardial ischemia caused by structural and/or functional abnormalities of pre-coronary arterioles and arterioles. While genetics and other factors play a role in CMD etiology, the key pathogenic mechanism remains unclear. Currently, the diagnostic procedure for CMD is still cumbersome, and there is a lack of effective targeted interventions. Single nucleotide polymorphisms (SNPs) offer promise in addressing these issues. SNPs, reflecting common genetic variations, have garnered extensive investigation across multiple diseases. Several SNPs associated with CMD have been discovered, and some have the potential to be therapeutic targets. Nevertheless, studies on CMD-related SNPs are relatively nascent and limited in number. In this review, we summarize the previously reported CMD-associated SNPs, delineate their pathophysiological mechanisms, and predict potentially important CMD sites by analyzing the SNPs linked to diseases sharing similar pathogenetic mechanisms and risk factors, such as coronary artery disease. We aim to explore reliable genetic markers implicated in CMD risk and prognosis, thereby providing a novel approach for early diagnosis and gene-targeted interventions of CMD in subsequent studies.

Protective role of the longevity-associated BPIFB4 gene on cardiac microvascular cells and cardiac aging

In recent years, the role of the cardiac microvasculature in modulating the symptoms and disease progression of patients affected by cardiac pathology has been reconsidered. The term cardiac microvascular disease (CMD) describes the set of functional and/or structural alterations of the cardiac microvasculature that reduce the ability of the heart to adequately increase its coronary blood flow to keep up with increased metabolic demand. CMD is involved in the evolution of heart disease of both ischemic and non-ischemic origin as well as in cardiac aging. The primary actors involved in this process are the cells of the stromal compartment, whose nature and biology are now investigated to a new level of detail thanks to single-cell omics studies. Recent studies on the genetics of extreme longevity have identified a polymorphic haplotype variant of the BPIFB4 gene that confers prolonged life span and health span, atheroprotective advantages, and an improved immune response. The aim of this review was to focus on the beneficial effects of the longevity-associated variant (LAV) of BPIFB4 on cardiac microvascular cell biology, providing novel and exciting mechanisms of its action directed against the development or progression of many age-related cardiovascular diseases, thus emphasizing its translational therapeutic potential.

Multimodality Imaging in the Diagnosis of Coronary Microvascular Disease: An Update

Coronary microvascular dysfunction (CMD) is characterized by structural and functional abnormalities in the coronary microvasculature which can lead to ischaemia and angina and is increasingly recognized as a major contributor to adverse cardiovascular outcomes. Despite its clinical importance, the diagnosis of CMD remains limited compared with traditional atherosclerotic coronary artery disease. Furthermore, the historical lack of non-invasive methods for detecting and quantifying CMD has hindered progress in understanding its pathophysiology and clinical implications. This review explores advancements in non-invasive cardiac imaging that have enabled the detection and quantification of CMD. It evaluates the clinical utility, strengths and limitation of these imaging modalities in diagnosing and managing CMD. Having improved our understanding of CMD pathophysiology, cardiac imaging can provide insights into its prognosis and enhance diagnostic accuracy. Continued innovation in imaging technologies is essential for advancing knowledge about CMD, leading to improved cardiovascular outcomes and patient care.

Underpinnings of Heart Failure With Preserved Ejection Fraction in Women - From Prevention to Improving Function. A Co-publication With the American Journal of Preventive Cardiology and the Journal of Cardiac Failure

Heart failure with preserved ejection fraction (HFpEF) represents a major clinical challenge with rising global prevalence. Women have a nearly double lifetime risk of developing HFpEF compared to heart failure with reduced ejection fraction (HFrEF). In HFpEF, sex differences emerge both in how traditional cardiovascular risk factors (such as hypertension, obesity, and diabetes) affect cardiac function and through distinct pathophysiological mechanisms triggered by sex-specific events like menopause and adverse pregnancy outcomes. These patterns influence not only disease development, but also therapeutic responses, necessitating sex-specific approaches to treatment. This review aims to synthesize existing knowledge regarding HFpEF in women including traditional and sex-specific risk factors, pathophysiology, presentation, and therapies, while outlining important knowledge gaps that warrant further investigation. The impact of HFpEF spans a woman's entire lifespan, requiring prevention and management strategies tailored to different life stages. While understanding of sex-based differences in HFpEF has improved, significant knowledge gaps persist. Through examination of current evidence and challenges, this review highlights promising opportunities for innovative research, therapeutic development, and clinical care approaches that could transform the management of HFpEF in women.

Partial Regulation of Ketone Metabolism by Hypoxia in H9C2 Cardiomyocytes

OBJECTIVE

Hypoxia plays a critical role in the pathophysiology of cardiomyopathy, myocardial infarction, and heart failure. Promoting ketone metabolism has been shown to be beneficial for myocardial cells under hypoxic conditions. However, the expression and regulatory mechanisms of key enzymes in the ketone pathway under hypoxic conditions are still unclear. This study aimed to investigate the effects of hypoxia on the expression of key enzymes in the ketone metabolic pathway and the underlying regulatory mechanisms involved.

METHODS

H9C2 myocardial cells were cultured for 6 h in an oxygen-glucose-deprived state, and the expression of various genes was detected by quantitative real-time PCR. ELISA and lactate dehydrogenase (LDH) cytotoxicity assay were used to measure CoAs, itaconic acid, and LDH levels, respectively, and the dependence of gene expression on hypoxia-inducible factor-1 alpha (HIF-1α) was evaluated using the inhibitor LW6.

RESULTS

H9C2 cardiomyocytes exhibited increased ketone body metabolism in response to hypoxia. Hypoxia induced the expression of the ketone body enzymes succinyl-CoA:3-oxoacid CoA transferase (SCOT/OXCT1), 3-hydroxybutyrate dehydrogenase 2 (BDH2), and acyl-CoA: cholesterol acyltransferase 1 (ACAT1) in cardiomyocytes, with a concomitant increase in the level of acyl-CoA and a decrease in the level of succinyl-CoA. The HIF-1α inhibitor LW6 could partially reverse the expression of BDH2 and ACAT1, as well as the levels of succinyl-CoA. Interestingly, however, hypoxia-induced SCOT/OXCT1 expression was not regulated by the HIF-1α inhibitor. In addition, hypoxia promoted the expression of inflammatory factors.

CONCLUSION

These data confirm the critical role of ketone metabolism in myocardial hypoxia and help to elucidate the pathophysiology of cardiomyopathy, myocardial infarction and heart failure.

Diabetic microvascular complications are associated with left ventricular hypertrophy in patients with type 2 diabetes mellitus

BACKGROUND

Left ventricular hypertrophy (LVH) is an important and common pathologic change in the heart of patients with diabetes mellitus. Microvascular complications have been reported to be involved in the development and process of LVH. This study aimed to explore the association between diabetic microvascular complications and LVH in patients with type 2 diabetes mellitus (T2DM).

MATERIAL AND METHODS

This is a cross-sectional study. A total of 2912 patients with T2DM were enrolled, including 360 patients with LVH and 2552 patients without LVH. Demographic data, medical history and laboratory indices were collected, along with information on diabetic microvascular complications and results from cardiac ultrasonography. The study utilized multivariable logistic regression to evaluate the independent effects of microvascular complications (DR, DPN, or DKD) and the cumulative number of these complications on the presence of LVH, while adjusting for potential confounding factors.

RESULT

In patients with T2DM, those with LVH were older and had higher body mass index, waist circumference and hip circumference than those without LVH. Additionally, the proportion of patients with diabetic retinopathy (DR) and diabetic kidney disease (DKD) was larger among those with LVH compared to those without LVH. After adjusting for potential confounding factors, DR and DKD were associated with increased odds of LVH (odds ratio [OR] = 1.351 and OR = 1.404, respectively). The risk of LVH also increased progressively in patients with two or more diabetic microvascular conditions compared to those with only one. In subgroup analysis, the risk of LVH increased with the number of microvascular conditions in male patients with T2DM.

CONCLUSIONS

Diabetic microvascular complications were significantly associated with LVH in T2DM. Moreover, the risk of LVH increased with the number of microvascular complications, particularly in males with T2DM.

Incident heart failure and recurrent coronary events following acute myocardial infarction

BACKGROUND AND AIMS

Recurrent myocardial infarction (MI) and incident heart failure (HF) are major post-MI complications. Herein, contemporary post-MI risks for recurrent MI and HF are described.

METHODS

A total of 6804 patients with a primary discharge diagnosis of MI at 28 Baylor Scott & White Health hospitals (January 2015 to December 2021) were studied. Patient characteristics, treatment, and outcomes, including incident HF, recurrent MI, all-cause death, and all-cause and cardiovascular rehospitalizations, were assessed. Landmark approach anchored at 3 months post-discharge was used to assess 1-year outcomes.

RESULTS

Median age was 69 years, 59.7% were male, and 76.7% had non-ST-elevation MI. Comorbidities included hypertension (89%), dyslipidaemia (87%), Type 2 diabetes (48%), and chronic kidney disease (34%); 17% had a history of MI and 23% of HF; 63% underwent percutaneous/surgical revascularization. In landmark-anchored 1-year outcomes (N = 6210), 413 (6.7%) patients died, 1730 (27.9%) had all-cause and 735 (11.8%) cardiovascular hospitalizations, 234 (3.8%) had recurrent MI. Of patients without history of HF, 1160 (23.8%) developed incident HF [42.2%, 26.7%, and 31.1% with ejection fraction (EF) < 40%, 41-49%, and >50%, respectively) within 3 months of discharge. Patients who developed HF had higher risk of death and hospitalizations (all P < .001), irrespective of EF. Of 2179 patients with EF > 50% without prevalent HF or HF during index hospitalization, 257 (11.8%) developed HF and 77 (3.5%) recurrent MI within 1 year.

CONCLUSIONS

In a contemporary post-MI cohort, the risk for incident HF was greater than recurrent MI, even among those with normal EF and no HF at discharge.

Coronary microvascular dysfunction endotypes: IMR tips and tricks

Coronary microvascular dysfunction (CMD) is an important clinical disease spectrum which has gained widespread attention due to chronic anginal symptoms, and worse clinical outcomes, with or without obstructive coronary artery disease (CAD). Coronary microcirculatory dysfunction is due to a wide array of mechanisms such as inflammation, platelet aggregation, vessel wall collagen deposition, imbalance of nitric oxide, free radicals, and sympathetic/parasympathetic simulation. As noted in this supplement, CMD can occur as a primary disease or co-exist with multi-array of diverse cardiac conditions such as CAD (old infarct), hypertrophic cardiomyopathy, Takotsubo cardiomyopathy, hypertension, or infiltrative diseases. CMD, which is often under diagnosed, leads to increase in medical expenses, decrease in quality of life, exacerbation of underlying conditions such as heart failure and even increased mortality. CMD presents a challenge for patients as well as physicians to manage. In this chapter, we review CMD and focus on its endotypes, techniques for microcirculatory assessment, associated tips and tricks and available treatment options.

Evolution of Coronary Microvascular Dysfunction Prevalence over Time and Across Diagnostic Modalities in Patients with ANOCA: A Systematic Review

Background: A considerable number of patients with angina undergo invasive coronary angiography, which might reveal non-obstructive coronary arteries (ANOCA). In this setting, they might have coronary microvascular disease (CMD). Its prevalence significantly varies in the literature. This systematic review aims to document the prevalence of CMD over time according to the diagnostic modalities. Methods: A systematic literature review was conducted using PubMed, the Cochrane Library, and Embase, covering publications from inception to 1 May 2024. Among 1471 identified articles, 297 full-text articles were assessed for eligibility. All studies reporting the prevalence of CMD in ANOCA patients based on invasive coronary artery (ICA), positron emission tomography-computed tomography (PET-CT), transthoracic echocardiography (TTE), or cardiac magnetic resonance (CMR) were included. Results: The review included 53 studies (published between 1998 and 2024), encompassing a total of 16,602 patients. Of these studies, 23 used ICA, 15 used PET-CT, 8 used TTE, and 7 used CMR. A statistically significant increase in CMD prevalence over time was observed across all diagnostic modalities (p < 0.05), except for PET-CT, which showed a consistent and stable prevalence over time. Notably, the prevalence rates from all of the diagnostic methods converged towards the 50% prevalence detected by PET-CT. Conclusions: The prevalence of CMD in patients with ANOCA is subject to debate. However, the current data suggest that regardless of the diagnostic method used, the most recent studies tend to converge towards a prevalence value of 50%, which has been consistently reported by PET-CT from the beginning.

Skeletal muscle adiposity, coronary microvascular dysfunction, and adverse cardiovascular outcomes

BACKGROUND AND AIMS

Skeletal muscle (SM) fat infiltration, or intermuscular adipose tissue (IMAT), reflects muscle quality and is associated with inflammation, a key determinant in cardiometabolic disease. Coronary flow reserve (CFR), a marker of coronary microvascular dysfunction (CMD), is independently associated with body mass index (BMI), inflammation and risk of heart failure, myocardial infarction, and death. The relationship between SM quality, CMD, and cardiovascular outcomes is not known.

METHODS

Consecutive patients (n = 669) undergoing evaluation for coronary artery disease with cardiac stress positron emission tomography demonstrating normal perfusion and preserved left ventricular ejection fraction were followed over a median of 6 years for major adverse cardiovascular events (MACEs), including death and hospitalization for myocardial infarction or heart failure. Coronary flow reserve was calculated as stress/rest myocardial blood flow. Subcutaneous adipose tissue (SAT), SM, and IMAT areas (cm2) were obtained from simultaneous positron emission tomography attenuation correction computed tomography using semi-automated segmentation at the 12th thoracic vertebra level.

RESULTS

Median age was 63 years, 70% were female, and 46% were nonwhite. Nearly half of patients were obese (46%, BMI 30-61 kg/m2), and BMI correlated highly with SAT and IMAT (r = .84 and r = .71, respectively, P < .001) and moderately with SM (r = .52, P < .001). Decreased SM and increased IMAT, but not BMI or SAT, remained independently associated with decreased CFR (adjusted P = .03 and P = .04, respectively). In adjusted analyses, both lower CFR and higher IMAT were associated with increased MACE [hazard ratio 1.78 (95% confidence interval 1.23-2.58) per -1 U CFR and 1.53 (1.30-1.80) per +10 cm2 IMAT, adjusted P = .002 and P < .0001, respectively], while higher SM and SAT were protective [hazard ratio .89 (.81-.97) per +10 cm2 SM and .94 (.91-.98) per +10 cm2 SAT, adjusted P = .01 and .003, respectively]. Every 1% increase in fatty muscle fraction [IMAT/(SM + IMAT)] conferred an independent 2% increased odds of CMD [CFR <2, odds ratio 1.02 (1.01-1.04), adjusted P = .04] and a 7% increased risk of MACE [hazard ratio 1.07 (1.04-1.09), adjusted P < .001]. There was a significant interaction between CFR and IMAT, not BMI, such that patients with both CMD and fatty muscle demonstrated highest MACE risk (adjusted P = .02).

CONCLUSIONS

Increased intermuscular fat is associated with CMD and adverse cardiovascular outcomes independently of BMI and conventional risk factors. The presence of CMD and SM fat infiltration identified a novel at-risk cardiometabolic phenotype.

Exploring Mortality and Prognostic Factors of Heart Failure with In-Hospital and Emergency Patients by Electronic Medical Records: A Machine Learning Approach

Purpose

As HF progresses into advanced HF, patients experience a poor quality of life, distressing symptoms, intensive care use, social distress, and eventual hospital death. We aimed to investigate the relationship between morality and potential prognostic factors among in-patient and emergency patients with HF.

Patients and Methods

A case series study: Data are collected from in-hospital and emergency care patients from 2014 to 2021, including their international classification of disease at admission, and laboratory data such as blood count, liver and renal functions, lipid profile, and other biochemistry from the hospital's electrical medical records. After a series of data pre-processing in the electronic medical record system, several machine learning models were used to evaluate predictions of HF mortality. The outcomes of those potential risk factors were visualized by different statistical analyses.

Results

In total, 3871 hF patients were enrolled. Logistic regression showed that intensive care unit (ICU) history within 1 week (OR: 9.765, 95% CI: 6.65, 14.34; p-value < 0.001) and prothrombin time (OR: 1.193, 95% CI: 1.098, 1.296; <0.001) were associated with mortality. Similar results were obtained when we analyzed the data using Cox regression instead of logistic regression. Random forest, support vector machine (SVM), Adaboost, and logistic regression had better overall performances with areas under the receiver operating characteristic curve (AUROCs) of >0.87. Naïve Bayes was the best in terms of both specificity and precision. With ensemble learning, age, ICU history within 1 week, and respiratory rate (BF) were the top three compelling risk factors affecting mortality due to HF. To improve the explainability of the AI models, Shapley Additive Explanations methods were also conducted.

Conclusion

Exploring HF mortality and its patterns related to clinical risk factors by machine learning models can help physicians make appropriate decisions when monitoring HF patients' health quality in the hospital.

Coronary Microvascular Function in Asymptomatic Middle-Aged Individuals With Cardiometabolic Risk Factors

BACKGROUND

In patients with ischemic heart disease, coronary microvascular dysfunction is associated with cardiovascular risk factors and poor prognosis; however, data from healthy individuals are scarce.

OBJECTIVES

The purpose of this study was to assess the impact of cardiovascular risk factors and subclinical atherosclerosis on coronary microvascular function in middle-aged asymptomatic individuals.

METHODS

Myocardial perfusion was measured at rest and under stress using cardiac magnetic resonance in 453 individuals and used to generate myocardial blood flow (MBF) maps and calculate myocardial perfusion reserve (MPR). Subclinical atherosclerosis was assessed using 3-dimensional vascular ultrasound of the carotid and femoral arteries and coronary artery calcium scoring at baseline and at 3-year follow-up.

RESULTS

Median participant age was 52.6 years (range: 48.9-55.8 years), and 84.5% were male. After adjusting for age and sex, rest MBF was directly associated with the number of the metabolic syndrome components present (elevated waist circumference, systolic and diastolic blood pressure, fasting glucose, and triglycerides and low high-density lipoprotein cholesterol), insulin resistance (homeostatic model assessment for insulin resistance), and presence of diabetes. MPR was reduced in the presence of several metabolic syndrome components, elevated homeostatic model assessment for insulin resistance, and diabetes. Stress MBF was inversely associated with coronary artery calcium presence and with global plaque burden. Higher stress MBF and MPR were associated with less atherosclerosis progression (increase in plaque volume) at 3 years.

CONCLUSIONS

In asymptomatic middle-aged individuals free of known cardiovascular disease, the presence of cardiometabolic risk factors and systemic (poly-vascular) subclinical atherosclerosis are associated with impaired coronary microvascular function. Better coronary microvascular function reduces atherosclerosis progression at follow-up. (Progression of Early Subclinical Atherosclerosis [PESA]; NCT01410318).

Coronary Microvascular Dysfunction: Insights on Prognosis and Future Perspectives

Coronary microvascular dysfunction (CMD) comprises a wide spectrum of structural and/or functional abnormalities of coronary microcirculation that can lead to myocardial ischemia. Emerging evidence has indicated that CMD is a relevant cause of morbidity and mortality and is associated with a high risk of major adverse cardiovascular events (MACEs) and heart failure with preserved ejection fraction as well as poor quality of life. This review aims to elucidate briefly the pathogenesis and diagnostic modalities of CMD and to shed light on contemporary evidence on the prognostic impact of CMD. Finally, we will provide an overview of novel emerging therapeutic strategies for CMD.

The role of coronary microcirculation in heart failure with preserved ejection fraction: An unceasing odyssey

Heart failure with preserved ejection fraction (HFpEF) represents an entity with complex pathophysiologic pathways, among which coronary microvascular dysfunction (CMD) is believed to be an important orchestrator. Research in the field of CMD has highlighted impaired vasoreactivity, capillary rarefaction, and inflammation as potential mediators of its development. CMD can be diagnosed via several noninvasive methods including transthoracic echocardiography, cardiac magnetic resonance, and positron emission tomography. Moreover, invasive methods such as coronary flow reserve and index of microcirculatory resistance are commonly employed in the assessment of CMD. As far as the association between CMD and HFpEF is concerned, numerous studies have highlighted the coexistence of CMD in the majority of HFpEF patients. Additionally, patients affected by both conditions may be facing an adverse prognosis. Finally, there is limited evidence suggesting a beneficial effect of renin-angiotensin-aldosterone system blockers, ranolazine, and sodium-glucose cotransporter-2 inhibitors in CMD, with further evidence being awaited regarding the impact of other pharmacotherapies such as anti-inflammatory agents.

Heart-brain microvascular MRI study: protocol for a multicentre, observational, cohort study in the UK assessing associations between small vessel disease of the heart and brain

INTRODUCTION

Ischaemic heart disease (IHD) and cerebrovascular disease are leading causes of morbidity and mortality worldwide. Cerebral small vessel disease (CSVD) is a leading cause of dementia and stroke. While coronary small vessel disease (coronary microvascular dysfunction) causes microvascular angina and is associated with increased morbidity and mortality. The vascular anatomy of the heart and brain is similar with conduit arteries distributed over the surface of these organs which in turn branch into a network of microscopic penetrating arteries which provide organ perfusion via an end-organ microcirculation. It has also been demonstrated that coronary microvascular dysfunction and CSVD share common vascular risk factors and pathophysiological mechanisms of disease. This has led to a link between the conditions being hypothesised, however, there is an evidence gap clearly demonstrating this relationship. The CorCMR (coronary microvascular angina cardiovascular magnetic resonance imaging) brain imaging study will provide novel insights into the associations between small vessel disease of the heart and brain and related clinical significance.

METHODS AND ANALYSIS

The CorCMR brain imaging study is a prospective, observational, multicentre cohort study including a blinded, central analysis and independent clinical trials unit; a prespecified study nested within the CorCMR trial. We will enrol patients with anginal symptoms who have undergone invasive coronary angiography which has demonstrated no obstructive coronary artery disease. The participants will then undergo brain MRI (to detect CSVD) immediately followed by a quantitative stress perfusion cardiac MRI (to detect coronary microvascular dysfunction). Participants will also undergo neurocognitive testing. The objectives of the study are to assess the prevalence of MRI features of CSVD in patients with angina and no obstructive coronary artery disease; to assess the association between coronary microvascular dysfunction and CSVD and to assess the association between CSVD and cognition.

ETHICS AND DISSEMINATION

The CorCMR study is approved by the UK National Research Ethics Service (Reference 20/WS/0159). Findings will be disseminated through peer-reviewed publications. All patients provided written informed consent.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov ID NCT04805814.

Repeat administration of human umbilical cord mesenchymal stem cells improves left ventricular diastolic function in mice with heart failure with preserved ejection fraction

Currently, no therapy is proven to effectively improve heart failure with preserved ejection fraction (HFpEF). Although stem cell therapy has demonstrated promising results in treating ischemic heart disease, the effectiveness of treating HFpEF with human umbilical cord mesenchymal stem cells (hucMSCs) remains unclear. To answer this question, we administered hucMSCs intravenously (i.v.), either once or repetitively, in a mouse model of HFpEF induced by a high-fat diet and NG-nitroarginine methyl ester hydrochloride. hucMSC treatment improved left ventricular diastolic dysfunction, reduced heart weight and pulmonary edema, and attenuated cardiac modeling (inflammation, interstitial fibrosis, and hypertrophy) in HFpEF mice. Repeat hucMSC administration had better outcomes than a single injection. In vitro, hucMSC culture supernatants reduced maladaptive remodeling in neonatal-rat cardiomyocytes. Ribonucleic acid sequencing and protein level analysis of left ventricle (LV) tissues suggested that hucMSCs activated the protein kinase B (Akt)/forkhead box protein O1 (FoxO1) signaling pathway to treat HFpEF. Inhibition of this pathway reversed the efficacy of hucMSC treatment. In conclusion, these findings indicated that hucMSCs could be a viable therapeutic option for HFpEF.

Sex differences and determinants of coronary microvascular function in asymptomatic adults with type 2 diabetes

BACKGROUND

Coronary microvascular dysfunction (CMD) is a significant complication in type 2 diabetes (T2D) and may be more common in women. We aimed to evaluate the sex differences and sex-specific clinical determinants of CMD in adults with T2D without prevalent cardiovascular disease.

METHODS

Single center pooled analysis of four prospective studies comparing asymptomatic people with T2D and controls. All subjects underwent comprehensive cardiovascular phenotyping with myocardial perfusion reserve (MPR) quantified with perfusion cardiovascular magnetic resonance (CMR). Participants with silent coronary disease were excluded. Multivariable linear regression was performed to identify determinants of MPR with an interaction term for sex.

RESULTS

Four hundred and seventy-nine T2D (age 57 ± 11 years, 42% [202/479] women) were compared with 116 controls (age 53 ± 11 years, 41% [48/116] women). Men with T2D, but not women, demonstrated worse systolic function and higher extracellular volume fraction than controls. MPR was significantly lower in T2D than controls (women, 2.6 ± 0.9 vs 3.3 ± 1.0, p < 0.001; men, 3.1 ± 0.9 vs 3.5 ± 1.0, p = 0.004), and lower in women than men with T2D (p < 0.001). More women than men with T2D had MPR <2.5 (46% [79/202] vs 26% [64/277], p < 0.001). There was a significant interaction between sex and body mass index (BMI) for MPR (p interaction <0.001). Following adjustment for clinical risk factors, inverse association with MPR were BMI in women (β = -0.17, p = 0.045) and systolic blood pressure in men (β = -0.14, p = 0.049).

CONCLUSION

Among asymptomatic adults with T2D, women had a greater prevalence of CMD than men. Risk factors modestly but significantly associated with CMD in asymptomatic people with T2D were BMI among women and systolic blood pressure among men.

Endothelial oestrogen-myocardial cyclic guanosine monophosphate axis critically determines angiogenesis and cardiac performance during pressure overload

AIMS

Oestrogen exerts beneficial cardiovascular effects by binding to specific receptors on various cells to activate nuclear and non-nuclear actions. Oestrogen receptor α (ERα) non-nuclear signalling confers protection against heart failure remodelling, involving myocardial cyclic guanosine monophosphate (cGMP)-cGMP-dependent protein kinase G (PKG) activation; however, its tissue-specific role remains elusive. Herein, we examine the cell type-specific role of ERα non-nuclear signalling in oestrogen-conferred protection against heart failure.

METHODS AND RESULTS

We first assessed the tissue-specific impacts of ERα on the cardiac benefits derived from oestrogen, utilizing endothelial ERα deletion (ERαf/f/Tie2Cre+) and myocyte ERα deletion (ERαf/f/αMHCCre+) female mice. Female mice were ovariectomized and the effect of estradiol (E2) was assessed in hearts exposed to 3 weeks of pressure overload [transverse aortic constriction (TAC)]. E2 failed to improve cardiac function in ERαf/f/Tie2Cre+ TAC hearts but provided benefits in ERαf/f/αMHCCre+ TAC hearts, indicating that endothelial ERα is essential. We next assessed the role of non-nuclear signalling in endothelial cells (ECs), employing animals with endothelial-specific inactivation of ERα non-nuclear signalling (ERαKI/KI/Tie2Cre+). Female ovariectomized mice were supplemented with E2 and subjected to 3-week TAC. ERαKI/KI/Tie2Cre+TAC hearts revealed exacerbated cardiac dysfunction and reduced myocardial PKG activity as compared to littermate TAC hearts, which were associated with attenuated myocardial induction of vascular endothelial growth factor (VEGF) and angiogenesis as assessed by CD31-stained capillary density. This phenotype of ERαKI/KI/Tie2Cre+was rescued by myocardial PKG activation from chronic treatment with a soluble guanylate cyclase (sGC) stimulator. We performed co-culture experiments to determine endothelial-cardiomyocyte interactions. VEGF induction by E2 in cardiac myocytes required a co-existence of intact endothelial ERα signalling in a nitric oxide synthase-dependent manner. On the other hand, VEGF was induced in myocytes directly with an sGC stimulator in the absence of ECs.

CONCLUSION

An endothelial oestrogen-myocardial cGMP axis stimulates angiogenic response and improves cardiac performance during pressure overload.

Specificities of Myocardial Infarction and Heart Failure in Women

Substantial evidence from previous clinical studies, randomized trials, and patient registries confirms the existence of significant differences in cardiac morphology, pathophysiology, prevalence of specific coronary artery disease (CAD), and clinical course of myocardial infarction (MI) between men and women. The aim of this review is to investigate the impact of sex or gender on the development and clinical course of MI, the mechanisms and features of left ventricular (LV) remodeling, and heart failure (HF). The main sex-related difference in post-MI LV remodeling is adverse LV dilatation in males versus concentric LV remodeling or concentric LV hypertrophy in females. In addition, women have a higher incidence of microvascular dysfunction, which manifests as impaired coronary flow reserve, distal embolism, and a higher prevalence of the no-reflow phenomenon. Consequently, impaired myocardial perfusion after MI is more common in women than in men. Regardless of age or other comorbidities, the incidence of reinfarction, hospitalization for HF, and mortality is significantly higher in females. There is therefore a "sex paradox": despite the lower prevalence of obstructive CAD and HF with reduced ejection fraction (HFrEF), women have a higher mortality rate after MI. Different characteristics of the coronary network, such as plaque formation, microvascular dysfunction, and endothelial inflammation, as well as the prolonged time to optimal coronary flow restoration, secondary mitral regurgitation, and pulmonary vascular dysfunction, lead to a worse outcome in females. A better understanding of the mechanisms responsible for MI occurrence, LV remodeling, and HF in men and women would contribute to optimized patient therapy that would benefit both sexes.

Coronary microvascular dysfunction and left heart filling pressures in patients with type 2 diabetes

AIMS

Patients with type 2 diabetes (T2D) have a high prevalence of diastolic dysfunction and heart failure with preserved ejection fraction (HFpEF), which in turn leads to an increased risk of hospitalization and death. However, the factors of risk and their relative importance in leading to higher left ventricular filling pressures are still disputed. We sought to clarify the associations of a wide range of invasive and non-invasive risk factors with cardiac filling pressures in high-risk T2D patients.

METHODS AND RESULTS

Patients with T2D at high risk of cardiovascular events were prospectively enrolled in this study. Participants were thoroughly phenotyped including right heart catheterization at rest and during exercise, echocardiography, urinary excretion of albumin (UACR), and quantification of their myocardial blood flow rate (MFR) using cardiac 82Rb-PET/CT. Of the 37 patients included in the study, 22 (59%) patients met invasive criteria for HFpEF. Only 2 out of 39 variables emerged as independent factors associated with left ventricular filling pressure as assessed by pulmonary capillary wedge pressure (PCWP) at rest; history of hypertension (coefficient: 2.6 mmHg [0.3; 5.0], P = 0.030) and MFR (P = 0.026). We found a significant inverse association between MFR and PCWP with a coefficient of -2.3 mmHg (-4.3; -0.3) in PCWP per integer change of MFR. The MFR ranged from 1.18 to 3.68 in our study, which corresponds to a difference in PCWP of approximately 6 mmHg between patients with the lowest compared to the highest MFR. During exercise, only 2 variables emerged as borderline independent factors associated with PCWP: myocardial flow reserve (coefficient: -4.4 [-9.6; 0.8], P = 0.091) and beta-blockers use (coefficient: 6.1 [-0.1; 12.4], P = 0.053).

CONCLUSIONS

In patients with type 2 diabetes without known HFpEF but risk factors for cardiovascular disease, myocardial blood flow rate was independently associated with PCWP at rest across the range from normal to abnormal left heart filling pressures. A clinically significant difference of 6 mmHg in PWCP was attributable to differences in MFR in patients with the lowest compared with the highest MFR values. This suggests that strategies than attenuate microvascular dysfunction could slow progression of increased left ventricular left heart filling pressures in patients at increased risk.

Sex differences of sequential changes in coronary blood flow and microvascular function in patients with suspected angina

AIMS

This study evaluated the sex differences of sequential changes in coronary blood flows and microvascular function in patients with suspected angina but with no obstructed coronary arteries.

METHODS

A total of 202 consecutive patients who experienced chest pain but had no significant coronary artery stenosis and who underwent adenosine stress echocardiography were included in the study. Coronary blood flow (CBF) velocities were measured at 1, 2, and 3 min after adenosine infusion.

RESULTS

The mean age was 61 years, and 138 (68%) were women. Approximately 40% of patients had coronary microvascular dysfunction (CMD, coronary flow velocity reserve < 2.3), with women exhibiting higher CMD prevalence. The left ventricular (LV) mass index was similar between men and women, while women exhibited higher baseline rate pressure products (RPP). At baseline, coronary blood flow velocities were similar between the sexes. However, CBF velocities in women gradually increased during the examination; and in men, the increase was abrupt and steep during the early stages of examination (p = 0.015 for interaction between time and sex), even with similar RPP in stress. Coronary flow velocity reserve was steadily lower in women compared to men (1 min, 2.09 ± 0.86 vs 2.44 ± 0.87; 2 min, 2.39 ± 0.72 vs 2.63 ± 0.85; 3 min, 2.45 ± 0.70 vs 2.68 ± 0.73).

CONCLUSIONS

In patients with suspected angina but with no obstructed coronary arteries, CMD was especially prevalent among women. Women exhibited higher oxygen consumption, while exhibiting slower and gradual increases in CBF velocities. Conversely, men exhibited faster and steeper increases in CBF velocities even with similar RPP in stress.

Expression of mRNA for molecules that regulate angiogenesis, endothelial cell survival, and vascular permeability is altered in endothelial cells isolated from db/db mouse hearts

Metabolic syndrome (MetS) is a condition that includes symptoms, such as obesity, hyperglycemia, and hypertension, which elevate cardiovascular risk. An impaired angiogenic response of endothelial cells (ECs) in heart and peripheral organs has been proposed in MetS, but the mechanisms of this phenomenon have not been thoroughly explored. Results obtained from evaluating the whole myocardium are inconsistent, since different types of cells react differently to MetS environment and a variety of molecular pathways are involved in the angiogenic response. Therefore, the aim of this paper was to study one selected pathway-the VEGF/VEGFR pathway, which regulates the angiogenic response and microvascular permeability in ECs isolated from db/db mouse hearts. The expression of mRNAs for VEGF/VEGFR axis proteins was assessed with RT-PCR in ECs isolated from control and db/db mouse myocardium. The density of CD31-, VEGFR2-, and VE-cadherin-positive cells was examined with confocal microscopy, and the ultrastructure of ECs was analyzed with transmission electron microscopy. The aortic ring assay was used to assess the capacity of ECs to respond to angiogenic stimuli. Our results showed a decreased number of microvessels, diminished expression of VE-cadherin and VEGFR2 and widened gaps between the ECs of microcapillaries. The aortic ring assay showed a diminished number of sprouts in db/db mice. These results may indicate that ECs in MetS enhance the production of mRNA for VEGF/VRGFR axis proteins, yet sprout formation and vascular barrier maintenance are limited. These novel data may provide a foundation for further studies on ECs dysfunction in MetS.

Utilizing Invasive Coronary Functional Testing in a Coronary Microvascular and Vasomotor Dysfunction Program: Methods and Considerations

BACKGROUND

Coronary microvascular and vasomotor dysfunction (CMVD) is associated with a threefold increased risk of major adverse cardiovascular events (MACE) and is the primary mechanism responsible for angina/ischemia in patients with nonobstructive coronary artery disease (ANOCA/INOCA). Proper assessment for CMVD is vital to provide targeted treatment and improve patient outcomes. Invasive coronary functional testing (ICFT) is the "gold standard," for CMVD assessment and can be used to diagnose all endotypes. However, there is a lack of standardization for ICFT protocols and use in the treatment of CMVD.

AIMS

To provide a comprehensive overview of ICFT protocols utilized at the Christ Hospital Womens Heart Center (TCH-WHC).

METHODS

Here, we outline our standard operating procedures for ICFT utilized at TCH-WHC, including the procedures two main methods: Doppler and Thermodilution. We describe our structured approach for ICFT referral and postdiagnostic clinical management utilized at The Christ Hospital Women's Heart Center (TCH-WHC) CMVD program. We then quantified how ICFT has contributed to growth of the TCH-WHC.

RESULTS

From October of 2020 until July of 2024, a total of 422 patients have undergone ICFT at TCH-WCH, 64% were performed via the Doppler protocol and 36% were performed via the Thermodilution protocol. Based on exclusive endotype categories, 19% had an endothelial-independent CMD alone, 19% had endothelial-dependent CMD or microvascular VSA alone, 3% had epicardial VSA alone, 42% had mixed disease (any combination of the above categories), and 17% had a normal ICFT.

CONCLUSIONS

ICFT provides opportunity to provide diagnostic clarity and optimize medical treatment for CMVD. TCH-WHC's structured approach for ICFT referral and protocol for conducting comprehensive ICFT which has been vital for the growth of our specialized CMVD program.

The Possible Role of Rosuvastatin Therapy in HFpEF Patients-A Preliminary Report

BACKGROUND

An increasing number of heart failure with preserved ejection fraction (HFpEF) syndromes has been reported in tandem with increasing age and burdens of obesity and cardiometabolic disorders. Identifying possible risk and modulatory HFpEF factors has significant epidemiological and clinical value. This study aimed to assess the prevalence of echocardiographic diagnostic criteria of left ventricular dysfunction in patients with chronic coronary syndrome depending on rosuvastatin therapy.

METHOD

There were 81 (33 (41%) male) consecutive patients with a median age of 70 (62-75) years, presenting with stable heart failure symptoms according to the New York Heart Association (NYHA) classification I to III. They presented with chronic coronary syndrome and were hospitalized between March and August 2024. Patients were divided according to the type of long-term lipid-lowering therapy into patients with rosuvastatin and with other statin therapy. The echocardiographic analysis based on diastolic dysfunction evaluation was performed on admission and compared with demographical, clinical, and laboratory results.

RESULTS

In the multivariable model for diastolic dysfunction prediction in the analyzed group based on three echocardiographic parameters, septal E' below 7 cm/s, lateral E' below 10 cm/s, and LAVI above 34 mL/m2, the following factors were found to be significant: sex (male) (OR: 0.19, 95% CI: 0.04-0.83, p = 0.027), obesity (defined as BMI > 30) (OR: 12.78, 95% CI: 2.19-74.50, p = 0.005), and rosuvastatin therapy (OR: 0.09, 95% CI: 0.02-0.51, p = 0.007).

CONCLUSIONS

Rosuvastatin therapy can be regarded as a possible protective therapy against left ventricular diastolic dysfunction in chronic coronary syndrome.

Moderately Increased Left Ventricular Filling Pressure Suggesting Early Stage of Heart Failure with Preserved Ejection Fraction in Patients with Invasively Assessed Coronary Microvascular Dysfunction

Background: With modern diagnostic tools, incidence ischemia with no obstructive coronary atherosclerosis (INOCA) and heart failure with preserved ejection fraction (HFpEF) are found to be much higher than previously believed, and-as they lead to adverse cardiovascular outcomes-their causes and development are subjects of ongoing research. There is growing evidence that coronary microvascular dysfunction might be the underlying cause of both INOCA and HFpEF. Methods: In 65 patients with effort angina but no obstructive coronary artery disease, the index of microvascular resistance and coronary flow reserve were measured invasively in the LAD. The echocardiographic parameters, including left atrial strain, left ventricular strain, and indices of left ventricular diastolic dysfunction, were compared between two groups of patients: those with normal coronary microcirculation parameters and those with impaired coronary microvascular function. Results: Patients with coronary microvascular dysfunction had higher a E/E' index than those with normal microvessel reactivity. This finding was further confirmed by ROC analysis. The groups did not differ significantly in values of other echocardiographic parameters, including the left ventricular and left atrial strain. The prevalence of classical cardiovascular risk factors was similar in both groups. Conclusions: The coexistence of impaired coronary microvascular function with moderately elevated left ventricular filling pressures might correspond to the co-development of early stages of coronary microvascular dysfunction and HFpEF.

Association of Coronary Microvascular Rarefaction and Myocardial Fibrosis With Coronary Artery Disease

BACKGROUND

To evaluate, in a cohort study, whether coronary microvasculature and myocardial structure differ between people with and without coronary artery disease (CAD).

METHODS AND RESULTS

We performed histological analysis of left ventricle free wall obtained at autopsy from 25 men and 23 women with ≥1 coronary artery with ≥75% area stenosis, and 25 men and 25 women without (no or minimal) CAD, matched for sex and age, who died suddenly from noncardiac causes. Decedents with myocardial infarction or other cardiac abnormality were excluded. Decedents with and without CAD had similar height and weight. Heart weight of decedents with CAD was higher than that of decedents without CAD (mean, 391 versus 364 g; mean difference, 27 g [95% CI, 0.3-54.0], P=0.048). Decedents with CAD had lower arteriole density (mean, 1.4 per mm2 versus 1.8 per mm2; mean difference, -0.4 per mm2 [95% CI, -0.6 to -0.2], P=0.0001), lower capillary length density (mean, 3164 versus 3701 mm/mm3; mean difference, -537 [95% CI, -787 to -286], P<0.0001), and higher total myocardial fibrosis (mean, 7.5% versus 5.7%; mean difference, 1.7% [95% CI, 1.0-2.5], P<0.0001), than decedents without CAD.

CONCLUSIONS

CAD was associated with coronary microvascular rarefaction and increased myocardial fibrosis. The association of CAD with coronary microvascular rarefaction and increased myocardial fibrosis may contribute to the increased risks of death, myocardial infarction and heart failure that accompany CAD, and may attenuate the impact of percutaneous coronary intervention on cardiovascular risk in people with stable angina.

Coronary microvascular dysfunction beyond the spectrum of chronic coronary syndromes

The prevalence of coronary microvascular dysfunction (CMD) beyond the spectrum of chronic coronary syndromes (CCS) is non-negligible, pertaining to pathophysiological and therapeutical implications. Thanks to the availability of accurate and safe non-invasive technique, CMD can be identified as a key player in heart failure, cardiomyopathies, Takotsubo syndrome, aortic stenosis. While CMD is widely recognized as a cause of myocardial ischemia leading to a worse prognosis even in the absence of obstructive coronary artery disease, the characterization of CMD patterns beyond CCS might provide valuable insights on the underlying disease progression, being potentially a "red flag" of adverse cardiac remodeling and a major determinant of response to therapy and outcomes. In this review, we aimed to provide an overview of the latest evidence on the prevalence, mechanistic and prognostic implications of CMD beyond the spectrum of CCS (i.e. heart failure, cardiomyopathies, Takotsubo syndrome, aortic stenosis).

Basal Coronary Microvascular Resistance Predicting Death and Heart Failure in Patients Without Functional Coronary Stenosis

BACKGROUND

Abnormal coronary microcirculation is linked to poor patient prognosis, so the aim of the present study was to assess the prognostic relevance of basal microvascular resistance (b-IMR) in patients without functional coronary stenosis.

METHODS AND RESULTS

Analyses of 226 patients who underwent intracoronary physiological assessment of the left anterior descending artery included primary endpoints of all-cause death and heart failure, as well as secondary endpoints of cardiovascular death and atherosclerotic vascular events. During a median follow-up of 2 years, there were 12 (5.3%) primary and 21 (9.3 %) secondary endpoints. The optimal b-IMR cutoff for the primary endpoints was 47.1 U. Kaplan-Meier curve analysis demonstrated worse event-free survival of the primary endpoints in patients with a b-IMR below the cutoff (χ2=21.178, P<0.001). b-IMR was not significantly associated with the secondary endpoints (P=0.35). A low coronary flow reserve (CFR; <2.5) had prognostic value for both endpoints (primary endpoints: χ2=11.401, P=0.001; secondary endpoints: (χ2=6.015; P=0.014), and high hyperemic microvascular resistance (≥25) was associated only with the secondary endpoints (χ2=4.420; P=0.036). Incorporating b-IMR into a clinical model that included CFR improved the Net Reclassification Index and Integrated Discrimination Improvement for predicting the primary endpoints (P<0.001 and P=0.034, respectively).

CONCLUSIONS

b-IMR may be a specific marker of the risk of death and heart failure in patients without functional coronary stenosis.

Alternative Factors in Possible Involvement of Coronary Microvascular Dysfunction in Older Patients with HFpEF

Objectives: Coronary microvascular dysfunction (CMD) is associated with many heart diseases, including heart failure (HF) with preserved ejection fraction (HFpEF). Invasive examinations for CMD detection are difficult in older patients with HFpEF, and the decision criteria for noninvasive CMD measurements are unclear. We aimed to identify alternative factors in the possible involvement of CMD in the progression and prognosis of HFpEF. Methods: We analyzed 607 patients with HFpEF who were hospitalized for acute decompensated HF without a history of coronary artery disease (CAD). Blood tests and transthoracic echocardiography were performed. We focused on left ventricular hypertrophy (LVH) and coronary perfusion pressure (diastolic blood pressure, dBP). Results: The patients with LVH showed reduced diastolic function (E/e') and a lower incidence of atrial fibrillation (AF) compared with those without LVH, with no differences in age or dBP. No differences were observed in all-cause mortality between patients with low and high dBP without LVH. In the patients with LVH, the incidence of all-cause mortality was significantly higher, with a lower incidence of AF, reduced renal function, and higher C-reactive protein levels in those with low dBP than in those with high dBP. The comprehensive diastolic functional index, diastolic elastance/arterial elastance, was markedly higher in the patients with LVH, especially in those with all-cause mortality. This index, but not E/e', was a significant prognostic index in the multivariate Cox hazard analysis when adjusting for age, sex and N-terminal pro-brain natriuretic peptide levels. Conclusions: LVH and dBP were clinically important factors in elderly HFpEF patients without a history of CAD.

PET myocardial perfusion imaging: Trends, challenges, and opportunities

Various non-invasive images are used in clinical practice for the diagnosis and prognostication of chronic coronary syndromes. Notably, quantitative myocardial perfusion imaging (MPI) through positron emission tomography (PET) has seen significant technical advancements and a substantial increase in its use over the past two decades. This progress has generated an unprecedented wealth of clinical information, which, when properly applied, can diagnose and fine-tune the management of patients with different types of ischemic syndromes. This state-of-art review focuses on quantitative PET MPI, its integration into clinical practice, and how it holds up at the eyes of modern cardiac imaging and revascularization clinical trials, along with future perspectives.

Relationship of Subendocardial Perfusion to Myocardial Injury, Cardiac Structure, and Clinical Outcomes Among Patients With Hypertension

BACKGROUND

Coronary microvascular dysfunction has been implicated in the development of hypertensive heart disease and heart failure, with subendocardial ischemia identified as a driver of sustained myocardial injury and fibrosis. We aimed to evaluate the relationships of subendocardial perfusion with cardiac injury, structure, and a composite of major adverse cardiac and cerebrovascular events consisting of death, heart failure hospitalization, myocardial infarction, and stroke.

METHODS

Layer-specific blood flow and myocardial flow reserve (MFR; stress/rest myocardial blood flow) were assessed by 13N-ammonia perfusion positron emission tomography in consecutive patients with hypertension without flow-limiting coronary artery disease (summed stress score <3) imaged at Brigham and Women's Hospital (Boston, MA) from 2015 to 2021. In this post hoc observational study, biomarkers, echocardiographic parameters, and longitudinal clinical outcomes were compared by tertiles of subendocardial MFR (MFRsubendo).

RESULTS

Among 358 patients, the mean age was 70.6±12.0 years, and 53.4% were male. The median MFRsubendo was 2.57 (interquartile range, 2.08-3.10), and lower MFRsubendo was associated with older age, diabetes, lower renal function, greater coronary calcium burden, and higher systolic blood pressure (P<0.05 for all). In cross-sectional multivariable regression analyses, the lowest tertile of MFRsubendo was associated with myocardial injury and with greater left ventricular wall thickness and volumes compared with the highest tertile. Relative to the highest tertile, low MFRsubendo was independently associated with an increased rate of major adverse cardiac and cerebrovascular events (adjusted hazard ratio, 2.99 [95% CI, 1.39-6.44]; P=0.005) and heart failure hospitalization (adjusted hazard ratio, 2.76 [95% CI, 1.04-7.32; P=0.042) over 1.1 (interquartile range, 0.6-2.8) years median follow-up.

CONCLUSIONS

Among patients with hypertension without flow-limiting coronary artery disease, impaired MFRsubendo was associated with cardiovascular risk factors, elevated cardiac biomarkers, cardiac structure, and clinical events.

ANOCA updated: From pathophysiology to modern clinical practice

Lately, a large number of stable ischemic patients, with no obstructed coronary arteries are being diagnosed. Despite this condition, which is being described as angina with no obstructive coronary arteries (ANOCA), was thought to be benign, recent evidence report that it is associated with increased risk for adverse cardiovascular outcomes. ANOCA is more frequent in women and, pathophysiologically, it is predominantly related with microvascular dysfunction, while other factors, such as endothelial dysfunction, inflammation and autonomic nervous system seem to also play a major role to its development, while other studies implicate ANOCA and microvascular dysfunction in the pathogenesis of heart failure with preserved ejection fraction. For establishing an ANOCA diagnosis, measurement including coronary flow reserve (CFR), microvascular resistance (IMR) and hyperemic microvascular resistance (HMR) are mostly used in clinical practice. In addition, new modalities, such as optical coherence tomography (OCT) are being tested and show promising results for future diagnostic use. Regarding management, pharmacotherapy consists of a wide selection of drugs, according to the respected pathophysiology of the disease (vasospastic angina or microvascular dysfunction), while research for new treatment options including interventional techniques, is currently ongoing. This review, therefore, aims to provide a comprehensive analysis of all aspects related to ANOCA, from pathophysiology to clinical managements, as well as clinical implications and suggestions for future research efforts, which will help advance our understanding of the syndrome and establish more, evidence-based, therapies.

Sex difference in human diseases: mechanistic insights and clinical implications

Sex characteristics exhibit significant disparities in various human diseases, including prevalent cardiovascular diseases, cancers, metabolic disorders, autoimmune diseases, and neurodegenerative diseases. Risk profiles and pathological manifestations of these diseases exhibit notable variations between sexes. The underlying reasons for these sex disparities encompass multifactorial elements, such as physiology, genetics, and environment. Recent studies have shown that human body systems demonstrate sex-specific gene expression during critical developmental stages and gene editing processes. These genes, differentially expressed based on different sex, may be regulated by androgen or estrogen-responsive elements, thereby influencing the incidence and presentation of cardiovascular, oncological, metabolic, immune, and neurological diseases across sexes. However, despite the existence of sex differences in patients with human diseases, treatment guidelines predominantly rely on male data due to the underrepresentation of women in clinical trials. At present, there exists a substantial knowledge gap concerning sex-specific mechanisms and clinical treatments for diverse diseases. Therefore, this review aims to elucidate the advances of sex differences on human diseases by examining epidemiological factors, pathogenesis, and innovative progress of clinical treatments in accordance with the distinctive risk characteristics of each disease and provide a new theoretical and practical basis for further optimizing individualized treatment and improving patient prognosis.

Novel diagnostic approaches and management of coronary microvascular dysfunction

The mechanism underlying ischaemic heart disease (IHD) has been primarily attributed to obstructive coronary artery disease (CAD). However, non-obstructive coronary arteries are identified in >50% of patients undergoing elective coronary angiography, recently leading to growing interest in the investigation and management of angina/ischaemia with non-obstructive coronary arteries (ANOCA/INOCA). INOCA is an umbrella term encompassing a multiple spectrum of possible pathogenetic entities, including coronary vasomotor disorders which consist of two major endotypes: coronary microvascular dysfunction (CMD) and vasospastic angina. Both conditions can coexist and be associated with concomitant obstructive CAD. Particularly, CMD refers to myocardial ischaemia due to reduced vasodilatory capacity of coronary microcirculation secondary to structural remodelling or impaired resting microvascular tone (functional) or a combination of both. CMD is not a benign condition and is more prevalent in women presenting with chronic coronary syndrome compared to men. In this setting, an impaired coronary flow reserve has been associated with increased risk of major adverse cardiovascular events. ANOCA/INOCA patients also experience impaired quality of life and associated increased healthcare costs. Therefore, research in this scenario has led to better definition, classification, and prognostic stratification based on the underlying pathophysiological mechanisms. The development and validation of non-invasive imaging modalities, invasive coronary vasomotor function testing and angiography-derived indices provide a comprehensive characterisation of CMD. The present narrative review aims to summarise current data relating to the diagnostic approach to CMD and provides details on the sequence that therapeutic management should follow.

Insights into the post-translational modifications in heart failure

Heart failure (HF), as the terminal manifestation of multiple cardiovascular diseases, causes a huge socioeconomic burden worldwide. Despite the advances in drugs and medical-assisted devices, the prognosis of HF remains poor. HF is well-accepted as a myriad of subcellular dys-synchrony related to detrimental structural and functional remodelling of cardiac components, including cardiomyocytes, fibroblasts, endothelial cells and macrophages. Through the covalent chemical process, post-translational modifications (PTMs) can coordinate protein functions, such as re-localizing cellular proteins, marking proteins for degradation, inducing interactions with other proteins and tuning enzyme activities, to participate in the progress of HF. Phosphorylation, acetylation, and ubiquitination predominate in the currently reported PTMs. In addition, advanced HF is commonly accompanied by metabolic remodelling including enhanced glycolysis. Thus, glycosylation induced by disturbed energy supply is also important. In this review, firstly, we addressed the main types of HF. Then, considering that PTMs are associated with subcellular locations, we summarized the leading regulation mechanisms in organelles of distinctive cell types of different types of HF, respectively. Subsequently, we outlined the aforementioned four PTMs of key proteins and signaling sites in HF. Finally, we discussed the perspectives of PTMs for potential therapeutic targets in HF.

Coronary Microvascular Dysfunction: A Guide for Clinicians

Dysfunction of the coronary microvasculature has become increasingly recognized as an important mechanism of myocardial ischemia in patients without obstructive coronary artery disease. The causes and management of coronary microvascular dysfunction remain poorly understood and are still largely based on extrapolation of epicardial coronary artery disease data. Quantification of myocardial blood flow and flow reserve have improved diagnosis, though important questions remain. In this review, we explain current understanding of the spectrum of pathophysiology of coronary microvascular dysfunction, summarize current diagnostic techniques to assess for coronary microvascular dysfunction, and appraise the limited data on management options specifically for patients with coronary microvascular dysfunction.

Beyond the Obstructive Paradigm: Unveiling the Complex Landscape of Nonobstructive Coronary Artery Disease

Traditionally focused on obstructive atherosclerosis, contemporary research indicates that up to 70% of patients undergoing coronary angiography for angina and ischemic symptoms do not exhibit significant stenoses. Nonobstructive coronary artery disease (CAD) has emerged as a prevalent phenotype among these patients. This review emphasizes the emerging understanding that nonobstructive coronary artery disease, encompassing conditions such as ANOCA (Angina with No Obstructive Coronary Artery Disease), INOCA (Ischemia with No Obstructive Coronary Artery Disease), and MINOCA (Myocardial Infarction with No Obstructive Coronary Arteries), represents the most prevalent phenotype in cardiac patients. It delves into the complex pathophysiology underlying these conditions, focusing on microvascular dysfunction and coronary vasoreactivity, which contribute to myocardial ischemia despite the absence of significant coronary obstructions. Additionally, the review critically examines the limitations of current treatments which primarily target obstructive lesions and underscores the necessity for tailored therapies that address the specific microvascular and immunoinflammatory pathways involved in nonobstructive CAD. The main focus of this review is to advocate for a shift in diagnostic and therapeutic strategies to better identify and manage this widely prevalent yet under-recognized subset of CAD.

Is the peripheral microcirculation a window into the human coronary microvasculature?

An increasing body of evidence suggests a pivotal role for the microvasculature in the development of cardiovascular disease. A dysfunctional coronary microvascular network, specifically within endothelial cells-the inner most cell layer of vessels-is considered a strong, independent risk factor for future major adverse cardiac events. However, challenges exist with evaluating this critical vascular bed, as many of the currently available techniques are highly invasive and cost prohibitive. The more easily accessible peripheral microcirculation has surfaced as a potential surrogate in which to study mechanisms of coronary microvascular dysfunction and likewise may be used to predict poor cardiovascular outcomes. In this review, we critically evaluate a variety of prognostic, physiological, and mechanistic studies in humans to answer whether the peripheral microcirculation can add insight into coronary microvascular health. A conceptual framework is proposed that the health of the endothelium specifically may link the coronary and peripheral microvascular beds. This is supported by evidence showing a correlation between human coronary and peripheral endothelial function in vivo. Although not a replacement for investigating and understanding coronary microvascular function, the microvascular endothelium from the periphery responds similarly to (patho)physiological stress and may be leveraged to explore potential therapeutic pathways to mitigate stress-induced damage.

Impact of Sex in the Incidence of Heart Failure in Patients with Chronic Coronary Syndrome

PURPOSE OF REVIEW

This review examines the available evidence concerning the incidence of heart failure in patients with chronic coronary syndrome, with a focus on gender differences.

RECENT FINDINGS

The incidence of heart failure in the context of chronic coronary syndrome presents conflicting data. Most of the available information stems from studies involving stable patients' post-acute coronary syndrome, revealing a wide range of incidence rates, from less than 3% to over 20%, observed over 5 years of follow-up. Regarding the gender differences in heart failure incidence, there is no consensus about whether women exhibit a higher incidence, particularly in the presence of evidence of obstructive coronary artery disease. However, in cases where obstructive coronary artery disease is absent, women may face a more unfavourable prognosis due to a higher prevalence of microvascular disease and heart failure with preserved ventricular function. The different profile of ischaemic heart disease in women difficult to establish differences in prognosis independently associated with female sex. Targeted investigations are essential to discern the incidence of heart failure in chronic coronary syndrome and explore potential gender-specific associations.

Microvascular resistance reserve before and after PCI: A serial FFR and [15O] H2O PET study

BACKGROUND AND AIMS

Microvascular Resistance Reserve (MRR) has recently been introduced as a microvasculature-specific index and hypothesized to be independent of coronary stenosis. The aim of this study was to investigate the change of MRR after percutaneous coronary intervention (PCI).

METHODS

In this post-hoc analysis from the PACIFC trials, symptomatic patients underwent [15O]H2O positron emission tomography (PET) and invasive fractional flow reserve (FFR) before and after revascularization. Coronary flow reserve (CFR) from PET and invasive FFR were used to calculate MRR.

RESULTS

Among 52 patients (87 % male, age 59.4 ± 9.4 years), 61 vessels with a median FFR of 0.71 (95 % confidence interval: 0.55 to 0.74) and a mean MRR of 3.80 ± 1.23 were included. Following PCI, FFR, hyperemic myocardial blood flow (hMBF) and CFR increased significantly (all p-values ≤0.001). MRR remained unchanged after PCI (3.80 ± 1.23 before PCI versus 3.60 ± 0.97 after PCI; p=0.23). In vessels with a pre-PCI, FFR ≤0.70 pre- and post-PCI MRR were 3.90 ± 1.30 and 3.73 ± 1.14 (p=0.56), respectively. Similar findings were observed for vessels with a FFR between 0.71 and 0.80 (pre-PCI MRR 3.70 ± 1.17 vs. post PCI MRR 3.48 ± 0.76, p=0.19).

CONCLUSIONS

Our study indicates that MRR, assessed using a hybrid approach of PET and invasive FFR, is independent of the severity of epicardial stenosis. These findings suggest that MRR is a microvasculature-specific parameter.

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.

Systemic impacts of metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH) on heart, muscle, and kidney related diseases

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as non-alcoholic fatty liver disease (NAFLD), is the most common liver disorder worldwide, with an estimated global prevalence of more than 31%. Metabolic dysfunction-associated steatohepatitis (MASH), formerly known as non-alcoholic steatohepatitis (NASH), is a progressive form of MASLD characterized by hepatic steatosis, inflammation, and fibrosis. This review aims to provide a comprehensive analysis of the extrahepatic manifestations of MASH, focusing on chronic diseases related to the cardiovascular, muscular, and renal systems. A systematic review of published studies and literature was conducted to summarize the findings related to the systemic impacts of MASLD and MASH. The review focused on the association of MASLD and MASH with metabolic comorbidities, cardiovascular mortality, sarcopenia, and chronic kidney disease. Mechanistic insights into the concept of lipotoxic inflammatory "spill over" from the MASH-affected liver were also explored. MASLD and MASH are highly associated (50%-80%) with other metabolic comorbidities such as impaired insulin response, type 2 diabetes, dyslipidemia, hypertriglyceridemia, and hypertension. Furthermore, more than 90% of obese patients with type 2 diabetes have MASH. Data suggest that in middle-aged individuals (especially those aged 45-54), MASLD is an independent risk factor for cardiovascular mortality, sarcopenia, and chronic kidney disease. The concept of lipotoxic inflammatory "spill over" from the MASH-affected liver plays a crucial role in mediating the systemic pathological effects observed. Understanding the multifaceted impact of MASH on the heart, muscle, and kidney is crucial for early detection and risk stratification. This knowledge is also timely for implementing comprehensive disease management strategies addressing multi-organ involvement in MASH pathogenesis.

Factors Contributing to Coronary Microvascular Dysfunction in Patients with Angina and Non-Obstructive Coronary Artery Disease

BACKGROUND

Coronary microvascular dysfunction (CMD), characterised by a reduced coronary flow reserve (CFR) or an increased index of microcirculatory resistance (IMR), has received considerable attention as a cause of chest pain in recent years. However, the risks and causes of CMD remain unclear; therefore, effective treatment strategies have not yet been established. Heart failure or coronary artery disease (CAD) is a risk factor for CMD, with a higher prevalence among women. However, the other contributing factors remain unclear. In this study, we assessed the risk in patients with angina and non-obstructive coronary artery disease (ANOCA), excluding those with heart failure or organic stenosis of the coronary arteries. Furthermore, we analysed whether the risk of CMD differed according to component factors and sex.

METHODS

This study included 84 patients with ANOCA (36 men and 48 women; mean age, 63 years) who underwent coronary angiography and functional testing (CFT). The CFT included a spasm provocation test (SPT), followed by a coronary microvascular function test (CMVF). In the SPT, patients were mainly provoked by acetylcholine (ACh), and coronary spasm was defined as >90% transient coronary artery constriction on coronary angiography, accompanied by chest pain or ischaemic changes on electrocardiography. In 15 patients (18%) with negative ACh provocation, ergonovine maleate (EM) was administered as an additional provocative drug. In the CMVF, a pressure wire was inserted into the left anterior descending coronary artery using intravenous adenosine triphosphate, and the CFR and IMR were measured using previously described methods. A CFR < 2.0 or IMR ≥ 25 was indicative of CMD. The correlations between various laboratory indices and CMD and its components were investigated, and logistic regression analysis was performed, focusing on factors where p < 0.05.

RESULTS

Of the 84 patients, a CFR < 2.0 was found in 22 (26%) and an IMR ≥ 25 in 40 (48%) patients, with CMD identified in 46 (55%) patients. CMD was correlated with smoking (p = 0.020) and the use of EM (p = 0.020). The factors that correlated with a CFR < 2.0 included the echocardiograph index E/e' (p = 0.013), which showed a weak but positive correlation with the CFR (r = 0.268, p = 0.013). Conversely, the factors correlated with an IMR ≥ 25 included RAS inhibitor usage (p = 0.018) and smoking (p = 0.042). Assessment of the risk of CMD according to sex revealed that smoking (p = 0.036) was the only factor associated with CMD in men, whereas the left ventricular mass index (p = 0.010) and low glycated haemoglobin levels (p = 0.012) were associated with CMD in women.

CONCLUSIONS

Our results indicated that smoking status and EM use were associated with CMD. The risk of CMD differed between the two CMD components and sex. Although these factors should be considered when treating CMD, smoking cessation remains important. In addition, CMD assessment should be performed carefully when EM is used after ACh provocation. Further validation of our findings using prospective studies and large registries is warranted.

Human cardiac metabolism

The heart is the most metabolically active organ in the human body, and cardiac metabolism has been studied for decades. However, the bulk of studies have focused on animal models. The objective of this review is to summarize specifically what is known about cardiac metabolism in humans. Techniques available to study human cardiac metabolism are first discussed, followed by a review of human cardiac metabolism in health and in heart failure. Mechanistic insights, where available, are reviewed, and the evidence for the contribution of metabolic insufficiency to heart failure, as well as past and current attempts at metabolism-based therapies, is also discussed.

Relationship between coronary microvascular dysfunction (CMD) and left ventricular diastolic function in patients with symptoms of myocardial ischemia with non-obstructive coronary artery disease (INOCA) by cardiovascular magnetic resonance feature-tracking

AIM

To investigate whether there was an association between coronary microvascular dysfunction (CMD) and left ventricular (LV) diastolic function in patients with myocardial ischemia with non-obstructive coronary artery disease (INOCA).

MATERIALS AND METHODS

Our study included 115 subjects with suspected myocardial ischemia that underwent stress perfusion cardiac magnetic resonance (CMR). They were divided into non-CMD and CMD two groups. CMR-derived volume-time curves and CMR-FT parameters were used to assess LV diastolic function using CVI42 software. The latter included global/regional LV peak longitudinal, circumferential, radial diastolic strain rate (LDSR, CDSR, RDSR). Logistic regression analysis was performed with CMR-FT strain parameters as independent variables and CMD as dependent variables, and the effect value was expressed as an odds ratio (OR).

RESULTS

Of the 115 patients, we excluded data from 23 patients and 92 patients (56.5% male；52 ± 12 years) were finally included in the study. Of these, 19 patients were included in the non-CMD group (49 ± 11 years) and CMD group included 73patient (52 ± 12 years). The regional CDSR (P=0.019), and regional RDSR (P=0.006) were significantly lower in the CMD group than in non-CMD group. But, regional LDSR in CMD group was higher than non-CMD (P=0.003). In logistic regression analysis, regional LDSR (adjusted β= 0.1, 95%CI 0.077, 0.349, p=0.002) and RDSR (adjusted β= 0.1, 95 % CI 0.066, 0.356, p=0.004) were related to CMD.

CONCLUSIONS

LV myocardial perfusion parameter MPRI was negatively correlated with LV diastolic function (CDSR) which needs to take into account the degree of diastolic dysfunction.

Prognostic value of myocardial flow reserve vs corrected myocardial flow reserve in patients without obstructive coronary artery disease

BACKGROUND

Myocardial flow reserve (MFR) by positron emission tomography (PET) is a validated measure of cardiovascular risk. Elevated resting rate pressure product (RPP = heart rate x systolic blood pressure) can cause high resting myocardial blood flow (MBF), resulting in reduced MFR despite normal/near-normal peak stress MBF. When resting MBF is high, it is not known if RPP-corrected MFR (MFRcorrected) helps reclassify CV risk. We aimed to study this question in patients without obstructive coronary artery disease (CAD).

METHODS

We retrospectively studied patients referred for rest/stress cardiac PET at our center from 2006 to 2020. Patients with abnormal perfusion (summed stress score >3) or prior coronary artery bypass grafting (CABG) were excluded. MFRcorrected was defined as stress MBF/corrected rest MBF where corrected rest MBF = rest MBF x 10,000/RPP. The primary outcome was major cardiovascular events (MACE): cardiovascular death or myocardial infarction. Associations of MFR and MFRcorrected with MACE were assessed using unadjusted and adjusted Cox regression.

RESULTS

3276 patients were followed for a median of 7 (IQR 3-12) years. 1685 patients (51%) had MFR <2.0, and of those 366 (22%) had an MFR ≥2.0 after RPP correction. MFR <2.0 was associated with an increased absolute risk of MACE (HR 2.24 [1.79-2.81], P < 0.0001). Among patients with MFR <2.0, the risk of MACE was not statistically different between patients with an MFRcorrected ≥2.0 compared with those with MFRcorrected <2.0 (1.9% vs 2.3% MACE/year, HR 0.84 [0.63-1.13], P = 0.26) even after adjustment for confounders (P = 0.66).

CONCLUSIONS

In patients without overt obstructive CAD and MFR< 2.0, there was no significant difference in cardiovascular risk between patients with discordant (≥2.0) and concordant (<2) MFR following RPP correction. This suggests that RPP-corrected MFR may not consistently provide accurate risk stratification in patients with normal perfusion and MFR <2.0. Stress MBF and uncorrected MFR should be reported to more reliably convey cardiovascular risk beyond perfusion results.

Significant Association of Serum Albumin With the Severity of Coronary Microvascular Dysfunction Using Dynamic CZT-SPECT

OBJECTIVE

Both low serum albumin (SA) concentration and coronary microvascular dysfunction (CMD) are risk factors for the development of heart failure (HF). We hypothesized that SA concentration is associated with myocardial flow reserve (MFR) and implicated in pathophysiological mechanism of HF.

METHODS

We retrospectively studied 454 patients undergoing dynamic cardiac cadmium-zinc-telluride myocardial perfusion imaging from April 2018 to February 2020. The population was categorized into three groups according to SA level (g/dL): Group 1: >4, Group 2: 3.5-4, and Group 3: <3.5. Myocardial blood flow (MBF) and myocardial flow reserve (MFR, defined as stress/rest MBF ratio) were compared.

RESULTS

The mean age of the whole cohort was 66.2 years, and 65.2% were men. As SA decreased, stress MBF (mL min-1 g-1) and MFR decreased (MBF: 3.29 ± 1.03, MFR: 3.46 ± 1.33 in Group 1, MBF: 2.95 ± 1.13, MFR: 2.51 ± 0.93 in Group 2, and MBF: 2.64 ± 1.16, MFR: 1.90 ± 0.50 in Group 3), whereas rest MBF (mL min-1 g-1) increased (MBF: 1.05 ± 0.42 in Group 1, 1.27 ± 0.56 in Group 2, and 1.41 ± 0.61 in Group 3). After adjusting for covariates, compared with Group 1, the odds ratios for impaired MFR (defined as MFR < 2.5) were 3.57 (95% CI: 2.32-5.48) for Group 2 and 34.9 (95% CI: 13.23-92.14) for Group 3. The results would be similar if only regional MFR were assessed. The risk prediction for CMD using SA was acceptable, with an AUC of 0.76.

CONCLUSION

Low SA concentration was associated with the severity of CMD in both global and regional MFR as well as MBF.