Prevalence of Coronary Microvascular Dysfunction Among Patients With Chest Pain and Nonobstructive Coronary Artery Disease

A VEGF gene therapy approach for the treatment of patients with coronary artery disease and refractory angina: assessment of clinical development

INTRODUCTION

Vascular endothelial growth factor (VEGF) gene therapy is a novel treatment strategy for refractory angina (RA) that works by promoting myocardial neoangiogenesis and collateral circulation formation. XC001 (encoberminogene rezmadenovec) is a novel, replication-deficient, non-integrating recombinant adenovirus vector formally referred to as AdVEGF-All6A+ engineered to produce three isoforms of VEGF A (121, 165, and 189) that are proven to induce neoangiogenesis and constructed specifically to increase the expression of VEGF 189 and 165 to improve safety because of its heparinsulfate binding domain.

AREAS COVERED

We review the clinical development of XC001 and results of the EXACT (Epicardial delivery of encoberminogene rezmadenovec [XC001] gene therapy for refractory Angina Coronary Treatment) phase 1 and phase 2 trials.

EXPERT OPINION

In initial trials, intramyocardial XC001 has been shown to be safe with signals for efficacy in decreasing myocardial perfusion defects, improving exercise duration, and anginal complaints in patients with RA. A Phase 2 trial using a novel percutaneous delivery catheter for endomyocardial delivery of XC001 is currently underway and has potential benefits in multiple other conditions, including as an adjunct therapy in patients undergoing CABG treatment at risk for incomplete revascularization, patients with coronary microvascular dysfunction, and others with peripheral arterial disease.

A Novel Angiography-Derived Computational Coronary Flow Reserve to Evaluate Non-Obstructive Coronary Artery Disease

Coronary flow reserve (CFR) is a key parameter for risk stratification in coronary artery disease but is limited by high cost, prolonged procedure time, and suboptimal reproducibility. We proposed a novel angiography-based method (Angio-CFR) to overcome these challenges and assessed its diagnostic performance. 107 consecutive patients underwent invasive coronary angiography with thermodilution-derived CFR (CFRthermo) were prospectively enrolled. Flow velocity at hyperemia and rest was estimated from angiographic images, and Angio-CFR was calculated as their ratio. Angio-CFR correlated well with CFRthermo (r = 0.72, p < 0.001), and showed good discrimination of CFRthermo < 2.5 (AUC = 0.879, p < 0.001) with an optimal cut-off of 2.5. The accuracy, sensitivity, and specificity of Angio-CFR were 81.71%, 83.33%, and 81.25%, respectively. Angio-CFR provides a pressure-wire-free method for coronary function assessment, demonstrating promising diagnostic accuracy and offering a more accessible approach for CFR measurement in clinical practice.

Novel Contrast-Derived Indices of Coronary Microvascular Function: Potential Clinical and Cost Benefits

BACKGROUND

Intravenous adenosine induces stable myocardial hyperemia for coronary microvascular function testing. Iodinated radiographic contrast media induce transient, submaximal hyperemia. We assessed the feasibility, diagnostic value, and potential cost-effectiveness of contrast-derived indices of microvascular function.

METHODS

Coronary flow reserve, index of microvascular resistance, and microvascular resistance reserve were assessed using a diagnostic guidewire. Intracoronary bolus thermodilution injections were performed at rest, immediately after an 8-mL bolus of iohexol, repeated after a second 8-mL bolus, and during intravenous adenosine infusion. Receiver operating characteristic analyses assessed the discriminatory ability of the contrast-derived indices (contrast-derived coronary flow reserve, contrast-derived index of microcirculatory resistance, contrast-derived microvascular resistance reserve) to detect abnormal adenosine-derived indices (coronary flow reserve <2.0, index of microvascular resistance ≥25, and microvascular resistance reserve <2.1).

RESULTS

Among 106 coronary arteries from 93 patients (median age 63 years; 62% female; 13% with diabetes), 88% of assessments were undertaken in the left anterior descending artery. Median fractional flow reserve was 0.88 (interquartile range, 0.85-0.92). Contrast-derived coronary flow reserve <2.0 (area under the curve 0.81; sensitivity 67%, specificity 80%, positive predictive value 40%, negative predictive value 92%), contrast-derived index of microcirculatory resistance >47 (area under the curve 0.82; 80%, 79%, 60%, 91%), and contrast-derived microvascular resistance reserve <1.9 (area under the curve 0.82; 67%, 89%, 35%, 97%) were best for predicting their adenosine-derived counterpart indices. There was good correlation on repeatability testing from the second contrast bolus. A hybrid approach reduced adenosine use by 40%, saving $30 800 (USA) or £8000 (UK) per 1000 vessels assessed.

CONCLUSIONS

Contrast-derived indices have high specificity and negative predictive value, enabling rapid exclusion of microvascular dysfunction. This method is feasible, clinically useful and cost-saving compared with routine adenosine testing.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04674449.

Cardiac Rehabilitation for Women with Heart Disease

Cardiovascular disease is the leading cause of morbidity and mortality in women globally. Cardiac rehabilitation (CR)-a comprehensive program including supervised progressive exercise, education, support, behavior modification, and nutritional guidance over 36 individual sessions-positively impacts morbidity, mortality, function, and quality of life. Overall, less than 30% of those who qualify are referred and participate in CR-referral and completion rates are significantly less in women compared with men despite evidence supporting equal benefit. Barriers contributing to these disparities have been identified, and CR programs can be modified to enhance the participation of women.

Challenges in diagnosing coronary microvascular dysfunction and coronary vasospasm

Chronic coronary syndromes (CCS) include 2 overlapping subgroups of patients - those with angina with nonobstructive coronary arteries (ANOCA), or ischaemia with non-obstructive coronary arteries (INOCA). A diagnosis of ANOCA-INOCA, is common and should be considered where angina is present and/or ischaemia is found on functional imaging in the absence of obstructive coronary artery disease (CAD) on coronary computed tomography angiography (CCTA) or invasive coronary angiography (ICA) (Ford and Berry, 2019). This review aims to provide an overview of contemporary challenges in the diagnosis of coronary microvascular dysfunction (CMD) and vasospastic disease, with a focus on recent guideline changes and current controversies. CMD and vasospastic angina (VSA) are increasingly acknowledged as an important and frequently overlooked, under investigated, and undertreated entities that contribute to ANOCA-INOCA (Samuels et al., 2023; Kunadian et al., 2020; Ford and Berry, 2019; Burgess and Mamas, 2024).

Cardiovascular risk factors are associated with cerebrovascular reactivity in young adults

INTRODUCTION

Endothelial dysfunction represents the earliest detectable stage of atherosclerosis, is associated with an increased risk of cardiovascular events, and predicts cardiovascular disease (CVD) more effectively than traditional cardiovascular risk factors. Cerebrovascular reactivity (CVR) provides an index of endothelial function in the brain. Poor CVR is associated with stroke, cerebral small vessel disease, dementia, and even coronary artery disease. Traditional CVD risk factors are associated with low CVR in patients with known CVD and in older cohorts. However, the relationship between cardiovascular risk profile and reduced CVR in young adults who do not yet have CVD is uncertain. We hypothesized that in young adults undergoing routine clinical fMRI examinations for non-vascular disease low CVR measures would be associated with increased cardiovascular risk factors.

METHODS

This cross-sectional study included adults with epilepsy undergoing a 3-Tesla fMRI scan of the brain for mapping of eloquent cortex with a "breath-hold task" to facilitate pre-operative planning for epilepsy-related surgery. Individuals with intracranial masses and those with baseline CVD were excluded. The task consisted of 5½, 20-s blocks of normal breathing interspersed with 20-s blocks of continuous breath holding. In breath hold fMRI scans, a voxel-wise comparison of brain T2 signal to an expected hemodynamic response curve is used to generate maps of voxel-wise t-statistics, indicating the probability that blood flow within a specific voxel had increased in response to changes in blood carbon dioxide levels. Using an axial slice 8 mm superior to the corpus callosum, a mean cerebral t-statistic was calculated for the slice as a comparative global measure of CVR in each patient. We retrospectively reviewed the charts of all individuals to characterize their clinical profile at the time of the fMRI. Based on the distribution of mean t-statistic values the sample was divided into two groups: high t-statistic ("normal reactivity") and low t-statistic value ("abnormal reactivity"). The distribution of cardiovascular risk factors was then compared across groups.

RESULTS

Between January 2014 and December 2023, 76 individuals underwent brain fMRI employing a "breath hold task" with suitable image quality for the current analysis (mean ± SD age, 35.46 ± 12.09 yrs.; 31.6 % female). Mean ± SD global CVR T-statistic was 3.97 ± 1.62. Low CVR was defined as a mean T-statistic ≤4.2 (n = 44, 57.9 %). Individuals with abnormal CVR were older (age: 45.1 ± 10.3 vs. 27.0 ± 3.4 yrs., p < 0.001), had a higher frequency of hypertension (31.8 % vs. 14.3 %, p = 0.0069) and hyperlipidemia (18.2 % vs. 3.1 %, p = 0.0449), and had higher systolic (123.5 ± 13.2 vs. 116.9 ± 12.2 mmHg, p = 0.0282) and diastolic blood pressures (77.9 ± 11.8 vs. 72.2 ± 8.9, p = 0.0141). Age, systolic blood pressure and hyperlipidemia were significantly associated with abnormal CVR in univariable and multivariable analyses (age, increase by 10 years OR: 2.00, 95 % CI 1.40-2.78, p = 0.0078; hyperlipidemia OR: 8.54, 95 % CI 1.07-184.9, p = 0.0049, and systolic blood pressure (OR for an increase in 10 mmHg: 1.57, 95 % CI 1.10-2.10, p = 0.0084).

CONCLUSION

Traditional cardiovascular risk factors, specifically age, systolic blood pressure and hyperlipidemia, are significantly associated with abnormal CVR in young adults without baseline CVD or cerebrovascular disease undergoing fMRI for reasons related to a diagnosis of epilepsy.

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.

Coronary Microvascular Dysfunction and Vasospastic Angina-Pathophysiology, Diagnosis and Management Strategies

Coronary artery disease is one of the leading public health problems in the world in terms of mortality and economic burden from the disease. Traditionally, the focus of research and clinical pathways leading to the diagnosis and treatment of coronary artery disease was on the more common variant of the disease resulting from atherosclerosis in the epicardial coronary arteries. However, coronary microvasculature, representing the vast majority of the total heart circulation, has the greatest influence on overall coronary resistance and, therefore, blood flow. Coronary microvascular dysfunction (CMD), characterized by structural or functional abnormalities in the microvasculature, significantly impacts myocardial perfusion. Endothelial dysfunction results in inadequate coronary dilation during exercise or spontaneous spasm in the microvasculature or epicardial arteries. A significant proportion of people presenting for coronary angiography in the context of angina have unobstructed epicardial coronary arteries yet are falsely reassured about the benign nature of their condition. Meanwhile, increasing evidence indicates that patients diagnosed with CMD as well as vasospastic angina (VSA) face an increased risk of Major Adverse Cardiovascular Events (MACEs), including death. The aim of this review is to outline the current practice with regard to invasive and non-invasive methods of CMD and VSA diagnosis and assess the evidence supporting the existing treatment strategies. These include endotype-specific pharmacological therapies, a holistic approach to lifestyle modifications and risk factor management and novel non-pharmacological therapies. Furthermore, the review highlights critical gaps in research and suggests potential areas for future investigation, to improve understanding and management of these conditions.

Coronary Endothelial Dysfunction and Vasomotor Dysregulation in Myocardial Bridging

Myocardial bridging (MB), a congenital variant where a coronary artery segment is tunneled within the myocardium, is increasingly recognized as a contributor to coronary endothelial and vasomotor dysfunction. Beyond the hallmark systolic compression observed on angiography, MB disrupts endothelial integrity, impairs the release of vasoactive substances, and induces vasomotor abnormalities. These effects exacerbate ischemic symptoms and predispose to atherosclerosis in the proximal segment, particularly in conditions such as ischemia/myocardial infarction with nonobstructive coronary arteries. Recent studies underscore MB's association with coronary vasospasm, microvascular endothelial dysfunction, and adverse cardiovascular outcomes, including sudden cardiac death. These findings highlight the interplay between MB's structural anomalies and functional impairments, with factors such as the bridge's length, depth, and orientation influencing its hemodynamic significance. Advances in imaging and coronary physiology assessment, including acetylcholine testing and stress diastolic fractional flow reserve/iFR/RFR, have enhanced diagnostic precision. This review explores the multifaceted impact of MB on coronary physiology, emphasizing its role in endothelial dysfunction and vasomotor regulation. Recognizing MB's contribution to cardiovascular disease is essential for accurate diagnosis and tailored management strategies aimed at mitigating ischemic risk and improving patient outcomes.

Clinical implications of coronary microvascular dysfunction in patients with non-obstructive coronary artery disease and role of the thermodilution method

More than 60% of patients undergoing coronary angiography present no coronary artery disease (CAD). Angina and myocardial ischemia are classically determined by epicardial vascular obstruction, but coronary microvascular dysfunction (CMD) may also represent a possible cause for these phenomena. Two endotypes of CMD have been recognized, with two different pathophysiological mechanisms: structural CMD, characterized by low coronary flow reserve (CFR) and high microvascular resistance (MVR) values; and functional CMD, characterized by low CFR and normal MVR values. According to the present data, almost half of patients with non-obstructive CAD have shown signs of CMD. For this reason, further investigations for microvascular function assessment should be considered when evaluating no-CAD patients complaining of angina or presenting signs of myocardial ischemia. The thermodilution method is currently becoming a widespread invasive technique due to its feasibility and high reproducibility for coronary physiology evaluation. Furthermore, a recently introduced technique - called continuous thermodilution - allows for direct measurement of absolute coronary flow and resistances. The role of this brand-new technique in the clinical scenario is however still to be fully investigated and its use is at present limited to research purposes only. Among no-CAD patients, both structural and functional CMD are related to a worse prognosis in term of mortality and major adverse cardiovascular events (MACE). In this review, we will discuss the present evidence supporting the definition, prevalence and clinical implication of the different forms of CMD and the technical aspects of its invasive assessment.

The role of non-invasive stress testing in the diagnosis of coronary microvascular disease

BACKGROUND

Angina with non-obstructive coronary artery disease (ANOCA) is commonly observed in patients with stable angina undergoing coronary angiography. Current guidelines recommend non-invasive stress testing as the first step in diagnosing coronary microvascular disease (CMD). This study aims to evaluate the diagnostic value of non-invasive stress testing in patients invasively diagnosed with CMD.

METHODS

We conducted a retrospective analysis of prospectively collected data. Eligible subjects were patients with angina who underwent NIST evaluation (echocardiography/ electrocardiography stress test or single-photon emission computerized tomography) prior to coronary angiography. All patients underwent invasive evaluation of microvascular function, which included the assessment of Coronary Flow Reserve, Index of Microcirculatory Resistance, and Resistive Reserve Ratio.

RESULTS

Overall, 140 patients (77 women, 67 ± 10 y/o) underwent NIST evaluation prior to coronary angiography, of whom 81 % were positive for ischemia. There was no difference in the prevalence of positive NIST between patients with abnormal compared with normal microvascular function tested invasively (81 % vs 82 %, p = 0.94). The prevalence of CMD was similar between patients with positive versus negative NIST (51 % vs 50 %, p = 0.94). Among 114 patients with positive NIST, 56 (49.2 %) had normal microvascular function, regardless of the type of stress test used (p = 0.94), the suspected territory of ischemia (p = 0.15), or the estimated severity of the ischemia (p = 0.63).

CONCLUSION

Non-invasive stress testing may have a limited predictive value in the diagnosis of CMD in ANOCA patients. Larger prospective studies are required for better understanding of the role these tests in the diagnosis and definition of CMD.

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.

FFR, iFR, CFR, and IMR: Results from clinical trials

In this review article, we provide an overview of the definition and application of fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), coronary flow reserve (CFR), and index of microvascular resistance (IMR) in the diagnosis, prognosis, and management of coronary microvascular dysfunction. We discuss their respective limitations as it relates to microvascular dysfunction. In each section, we review the most recent evidence supporting their use in microvascular and epicardial coronary artery disease. We also highlight specific clinical conditions with emerging indications for the use of these indices, including in the setting of microvascular dysfunction due to acute myocardial infarction, heart failure with preserved ejection fraction, and post-cardiac transplant.

Diagnosis and Management of Acute Coronary Syndrome Patients Without Obstructive Epicardial Stenosis

PURPOSE OF REVIEW

What is the pathophysiology and clinical findings as well as management of patients presenting with INOCA/MINOCA (Ischemia/Myocardial Infarction with Non-Obstructive Coronary Arteries).

RECENT FINDINGS

INOCA/MINOCA has a complex pathophysiology. In this review article, we aim to summarize the complex pathophysiology and clinical diagnosis, and review the current management 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.

The additional impact of metabolic syndrome on left ventricular deformation and myocardial energetic efficiency impairment in ischemia with nonobstructive coronary arteries patients

BACKGROUND

Ischemia with nonobstructive coronary arteries (INOCA) has high morbidity, mortality, and poor quality of life. Metabolic syndrome (MetS) is a complex of multiple cardiac metabolic risk factors, significantly increasing the risk of major adverse cardiovascular events in INOCA patients. The study aimed to investigate the aggravating effect of MetS on left ventricular (LV) deformation and function impairment in INOCA patients.

MATERIALS AND METHODS

This study collected 104 INOCA patients (INOCA [MetS-]: n = 56; INOCA [MetS+]: n = 48) and 41 sex- and age-matched controls. LV function, indexed myocardial energetic efficiency (MEEI), and LV global peak strains (including radial, circumferential, and longitudinal directions) were measured among the three groups. The independent factors of reduced MEEI and impaired LV function and strain parameters for all INOCA patients were assessed using multivariable linear regression analyses.

RESULTS

In contrast to the INOCA (MetS-) group, the indexed LV stroke volume (LVSVI) (49.57 ± 11.58 mL/m2 vs. 42.58 ± 12.23 mL/m2, p = 0.007), MEEI [0.85(0.70-1.03) ml/s/g vs. 0.75(0.54-0.91) ml/s/g, p = 0.045] and LV global longitudinal peak strain (GLPS) (- 13.26 ± 2.86% vs. -10.95 ± 3.93%, p = 0.001) reduced in the INOCA (MetS+) group. Compared with the controls, LV GLPS decreased in the INOCA (MetS-) group (- 15.14 ± 2.83% vs. -13.26 ± 2.86%, p = 0.017). MetS was negatively associated with LVSVI, MEEI, and LV GLPS (all p < 0.05). After multivariable adjustment, MetS was found to be an independent factor of decreased LVSVI (β = -0.231, p = 0.012), MEEI (β = -0.262, p = 0.009), and LV GLPS (β = -0.266, p = 0.002) in INOCA patients. Using calcium channel blockers medication (β = 0.320, p = 0.001) and hypertension (β = -0.298, p = 0.002) were also independently associated with impaired MEEI.

CONCLUSIONS

MetS aggravated LV deformation and function impairment in patients with INOCA. MetS was found to be an independent factor of impaired MEEI and LV GLPS, the further decrease of MEEI and LV GLPS in INOCA patients caused by MetS might involve the synergistic injury mechanism. Early diagnosis and treatment of MetS in patients with INOCA are important.

Diagnostic performance of multi-branch coronary angiography-based index of microcirculatory resistance: a novel approach

Background

Wire-based index of microcirculatory resistance (IMR) utilizing pressure wires and thermodilution techniques for the assessment of coronary microcirculatory function, presents challenges for clinical routine use due to its complexity, time-consuming, and costly. This study introduces a novel multi-branch and wire-free method for IMR calculation based on coronary angiography. The diagnostic performance of CAG-IMR is validated within a retrospective single-center investigation.

Methods

In a retrospective single-center study, 139 patients with 201 vessels were evaluated using CAG-IMR for coronary microvascular dysfunction (CMD) detection, utilizing wire-based IMR as the reference standard. CMD was determined based on wire-based IMR ≥25U. CAG-IMR was independently calculated from diagnostic coronary angiography in a blinded fashion, employing the same diagnostic threshold of 25U for CMD identification.

Results

CAG-IMR demonstrated significant correlation (r = 0.84, p < 0.001) and good diagnostic performance AUC = 0.97 (95% CI: 0.95-0.99) compared to wire-based IMR. It exhibited the overall diagnostic accuracy at 95.0% (95% CI: 92.0%-98.0%), alongside high sensitivity (92.7%) and specificity (95.6%). The positive predictive value (PPV) stood at 84.4%, and the negative predictive value (NPV) reached 98.1%.

Conclusions

This study introduces CAG-IMR, a novel, multi-branch and wire-free method for IMR calculation. The indicator demonstrates good diagnostic accuracy and correlation with wire-based IMR in a cohort of 139 patients and 201 vessels, with the potential to enhance clinical CMD assessment.

Sex-Based Differences and Outcomes in Unselected Patients Undergoing Coronary Angiography

Background: The study investigates sex-related differences and outcomes in unselected patients undergoing invasive coronary angiography (CA). Sex-based differences with regard to baseline characteristics and management of patients with cardiovascular disease have yet been demonstrated. However, their impact on long-term outcomes in unselected patients undergoing CA remains unknown. Methods: Consecutive patients undergoing invasive CA from 2016 to 2022 were included at one institution. Prognosis of male and female patients undergoing CA was investigated with regard to the primary endpoint of rehospitalization for heart failure (HF) at 36 months. Secondary endpoints comprised the risk of acute myocardial infarction (AMI) and coronary revascularization at 36 months, as well as in-hospital all-cause mortality. Statistical analyses included Kaplan-Meier analyses, as well as uni- and multivariable Cox proportional regression analyses. Results: From 2016 to 2022, 7691 patients undergoing CA were included (males: 65.1%; females: 34.9%). Males had a higher prevalence of coronary artery disease (CAD) (76.2% vs. 57.4%; p = 0.001), alongside a higher prevalence of 3-vessel CAD compared to females (33.9% vs. 20.3%; p = 0.001). The risk of rehospitalization for HF at 36 months was higher in males compared to females (22.4% vs. 20.3%; p = 0.036; HR = 1.127; 95% CI: 1.014-1.254; p = 0.027), which was no longer observed after multivariable adjustment. Male sex was associated with a higher risk of coronary revascularization (9.6% vs. 5.9%; p = 0.001; HR = 1.659; 95% CI: 1.379-1.997; p = 0.001), which was still evident after multivariable adjustment (HR = 1.650; 95% CI 1.341-2.029; p = 0.001). However, neither the risk of AMI at 36 months (8.1% vs. 6.9%; p = 0.077), nor the risk of in-hospital all-cause mortality (6.9% vs. 6.5%; p = 0.689) differed significantly between the two sexes. Conclusions: In consecutive patients undergoing coronary angiography, male sex was independently associated with an increased risk of coronary revascularization, but not HF-related rehospitalization.

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.

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.

Sex-related differences in demographics, diagnosis and management of patients with chronic coronary syndromes

AIMS

The impact of sex-related factors on current clinical management and outcomes of chronic coronary syndromes (CCS) are unclear.

METHODS

All patients belonging to the prospective, nationwide START registry were included. Their baseline characteristics, diagnostic workup, revascularization strategy, pharmacological treatment and 1-year clinical outcomes were compared with respect to sex overall and in age tertiles.

RESULTS

A total of 5070 consecutive patients were included. Most patients were males (80.1%). As expected, the prevalence of females increased with age. Distribution of risk factors and history of cardiovascular disease were different depending on sex, as well as diagnostic workup, with lower use of exercise stress testing in women (25.1% vs. 36.7%, P < 0.0001). The use of coronary angiography was similar in the two groups. Women had lower rates of multivessel coronary artery disease (CAD) (33.0% vs. 40.6% P < 0.0001) and higher rates of nonobstructive CAD (18.3% vs. 11.3%, P < 0.0001). Rates of myocardial revascularization were similar, but women were more likely to receive percutaneous coronary intervention than men (84.3% vs. 77.8%, P < 0.0001) and less likely to receive surgical/hybrid revascularization (10.0% vs. 15.1%, P < 0.0001). At 12-month follow-up, no differences were observed for the combined endpoint of all-cause mortality, re-hospitalization for myocardial infarction, heart failure, stroke or myocardial revascularization between males and females; however, a significantly worse perceived quality of life was observed in women.

CONCLUSIONS

In a large nationwide cohort of patients with CCS, clinical outcomes were not different depending on sex. However, several differences in the diagnostic work-up, treatment strategies and quality of life were found between sexes.

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.

Elevated Inflammation and Adhesion Molecule hsCRP, GDF-15 and VCAM-1 in Angina Patients with Non-obstructive Coronary Artery Disease

Background

Non-obstructive coronary artery disease (NOCAD) is a condition in stable patients that experience angina despite not having significant coronary obstructive lesion. Knowledge on the role of certain biomarkers in patients with NOCAD is still limited. This study aimed to evaluate the roles of inflammation and adhesion molecules in the development of NOCAD. The correlations between the peripheral and coronary levels of the inflammatory biomarkers and adhesion molecules were also investigated.

Methods

In this cross-sectional study, symptomatic angina patients scheduled for coronary angiograms were recruited and separated into obstructive coronary artery disease (OCAD) and NOCAD groups based on those angiograms. Peripheral and coronary blood samples were taken to measure inflammation biomarkers [high sensitivity C-reactive protein (hsCRP) and growth differentiation factor 15 (GDF-15)], and adhesion molecules [vascular cell adhesion molecule-1 (VCAM-1)]. Subjects without angina symptoms were recruited for the control group.

Results

The hsCRP, GDF-15, and VCAM-1 levels were higher in the OCAD and NOCAD groups than in the control group. VCAM-1 levels successfully predicted the incidence of NOCAD [p = 0.010, area under the curve (AUC) = 0.716]. All biomarkers' levels in the peripheral and coronary blood were correlated in OCAD and NOCAD patients (p < 0.001).

Conclusion

Elevated levels of the hsCRP, GDF-15, and VCAM-1 were found with NOCAD, despite the absent of significant coronary obstruction. VCAM-1 successfully predicted NOCAD and may thus serve as an early NOCAD biomarker. Significant correlations of hsCRP, GDF-15, and VCAM-1 level in peripheral and coronary blood indicate that the peripheral levels of these biomarkers reflect the levels and changes that occur at the coronary level.

Coronary angiography: a review of the state of the art and the evolution of angiography in cardio therapeutics

Traditionally, coronary angiography was restricted to visual estimation of contrast-filled lumen in coronary obstructive diseases. Over the previous decades, considerable development has been made in quantitatively analyzing coronary angiography, significantly improving its accuracy and reproducibility.  Notably, the integration of artificial intelligence (AI) and machine learning into quantitative coronary angiography (QCA) holds promise for further enhancing diagnostic accuracy and predictive capabilities. In addition, non-invasive fractional flow reserve (FFR) indices, including computed tomography-FFR, have emerged as valuable tools, offering precise physiological assessment of coronary artery disease without the need for invasive procedures. These innovations allow for a more comprehensive evaluation of disease severity and aid in guiding revascularization decisions. This review traces the development of QCA technologies over the years, highlighting key milestones and current advancements. It also explores prospects that could revolutionize the field, such as AI integration and improved imaging techniques. By addressing both historical context and future directions, the article underscores the ongoing evolution of QCA and its critical role in the accurate assessment and management of coronary artery diseases. Through continuous innovation, QCA is poised to remain at the forefront of cardiovascular diagnostics, offering clinicians invaluable tools for improving patient care.

Feasibility and Improved Diagnostic Yield of Intracoronary Adenosine to Assess Microvascular Dysfunction With Bolus Thermodilution

BACKGROUND

Bolus thermodilution and intravenous adenosine are established methods for coronary microcirculatory assessment. Yet, its adoption remains low, partly due to procedural time and patient discomfort associated with intravenous adenosine. We investigated differences between intracoronary and intravenous adenosine using bolus thermodilution in terms of microcirculatory indices, procedural time, and side effects associated with adenosine in patients with myocardial ischemia and nonobstructive coronary arteries.

METHODS AND RESULTS

In this prospective, observational study, 102 patients with suspected myocardial ischemia and nonobstructive coronary arteries underwent measurements of mean transit time, coronary flow reserve, index of microcirculatory resistance, procedure time and patient tolerability with low-dose intracoronary adenosine, high-dose intracoronary adenosine (HDIC), and intravenous adenosine. HDIC induced greater hyperemia compared with low-dose intracoronary IC adenosine and intravenous adenosine with a shorter hyperemic mean transit time, P<0.0001. Coronary flow reserve was higher and index of microcirculatory resistance lowest with HDIC, compared with low-dose intracoronary IC adenosine and intravenous adenosine, P<0.05. Low coronary flow reserve was downgraded from 21% with intravenous adenosine to 10% with HDIC adenosine (P=0.031); high index of microcirculatory resistance was downgraded from 23% with intravenous adenosine to 14% with HDIC (P=0.098). Intracoronary adenosine was associated with lower procedural times (P<0.0001). More patients experienced chest pain with intravenous adenosine (P<0.01) and the chest pain intensity was higher compared with intracoronary adenosine (P<0.0001).

CONCLUSIONS

In patients with suspected myocardial ischemia and nonobstructive coronary arteries undergoing coronary microcirculatory assessment with bolus thermodilution, the use of HDIC compared with intravenous adenosine was associated with enhanced induction of hyperemia. The use of intracoronary adenosine allowed for a shorter procedure time and was better tolerated.

REGISTRATION+

URL: clinicaltrials.gov; Unique Identifier: NCT04827498.

Assessment of Coronary Microvascular Dysfunction by Angiography-Based Index of Microcirculatory Resistance: An Indirect Meta-Analysis

INTRODUCTION

There is a lack of consensus on diagnosing coronary microvascular dysfunction (CMD) using the angiography-based index of microcirculatory resistance (Angio-IMR) due to the absence of evidence. This study aimed to explore the efficacy of Angio-IMR in diagnosing CMD.

METHODS

A systematic search was conducted in PubMed, Embase, Scopus, and the Cochrane Library for studies primarily focusing on Angio-IMR diagnosing CMD, using IMR as the gold standard. The primary results were pooled sensitivity, specificity, and the area under the curve (AUC).

RESULTS

A total of 15 studies involving 2,202 individuals and 2,330 vessels were included in our study, Angio-IMR demonstrated high performance in predicting IMR with overall pooled sensitivity and specificity of 0.84 (95% confidence interval (CI): 0.81-0.87) and 0.87 (95% CI: 0.83-0.99), respectively, and AUC = 0.91 (95% CI: 0.89-0.94). This indicates that Angio-IMR has good diagnostic characteristics. Subgroup analysis by indirect meta-analysis showed higher sensitivity in the rest state. However, there is no significant difference in sensitivity and specificity between the hyperemic and rest states when using the AccuIMR system. Furthermore, sensitivity and specificity were more pronounced in the group without coronary pressure monitoring compared to the group with monitoring.

CONCLUSION

Angio-IMR is an alternative tool to identify CMD.

Peripheral Endothelial Dysfunction Is Associated With Incident Major Depressive Disorder

BACKGROUND

A subset of individuals with major depressive disorder (MDD) have a high burden of cardiovascular risk factors and cerebral small-vessel disease, implicating vascular disease in the development of depression. Cross-sectional studies demonstrate a link between endothelial dysfunction and MDD, but the prospective association between peripheral endothelial dysfunction (PED) and an incident diagnosis of MDD is unknown.

METHODS AND RESULTS

Patients undergoing a baseline assessment of cardiovascular risk were evaluated for PED using reactive hyperemia-peripheral arterial tonometry (≤1.8 consistent with PED). Patient medical records were reviewed to identify those who underwent a formal clinical evaluation of MDD after the index PED evaluation. The frequency of PED was compared in those with and without MDD. Logistic regression analyses were performed to assess the association between baseline PED and incident MDD. Between January 2006 and December 2020, 1614 patients underwent testing for PED. Four hundred eighty-four (30.1%) patients underwent a formal evaluation for MDD after (0-15 years) the index procedure (mean±SD age, 52.8±13.8 years; 65.2% women). Of these, 157 (32.4%) had PED and 108 (31.0%) were diagnosed with MDD. Individuals with MDD had a higher frequency of PED (40.2% versus 30.2%; P=0.034) compared with those without MDD. In multivariable analyses, PED was significantly associated with MDD (odds ratio, 2.3 [95% CI, 1.4-3.8]; P<0.001).

CONCLUSIONS

PED is significantly associated with incident MDD. Thus, PED may be a useful marker to identify individuals at increased risk of depression who may benefit from more frequent and earlier management strategies.

The Role of Cardiac Computed Tomography Angiography in Risk Stratification for Coronary Artery Disease

Coronary computed tomography angiography (CCTA) allows the assessment of the presence and severity of obstructive and nonobstructive atherosclerotic coronary artery disease. With software developments incorporating artificial intelligence-based automated image analysis along with improved spatial resolution of CT scanners, volumetric measurements of atherosclerotic plaque, detection of high-risk plaque features, and delineation of pericoronary adipose tissue density can now be readily and accurately evaluated for a given at-risk patient. Many of these expanded diagnostic measures have been shown to be prognostically useful for prediction of major adverse cardiac events. The incremental value of plaque quantification over diameter stenosis has yet to be thoroughly discovered in current studies. Furthermore, the physiological significance of lesions can also be assessed with CT-derived fractional flow reserve, myocardial CT perfusion, and more recently shear stress, potentially leading to selective invasive coronary angiography and revascularization. Along with these technological advancements, there has been additional high-quality evidence for CCTA including large randomized clinical trials supporting high-level recommendations from many international clinical practice guidelines. Current trials largely compare a CCTA vs functional testing strategy, yet there is minimal evidence on CCTA plaque-guided therapeutic trials to measure regression of atherosclerosis and prevention of major coronary artery disease events. In this review, we summarize current evidence on comprehensive risk assessment with CCTA and future directions.

The ANOCA/INOCA Dilemma Considering the 2024 ESC Guidelines on Chronic Coronary Syndromes

Cardiovascular disease remains a significant cause of morbidity and mortality worldwide, and its manifestations continue to pose a challenge in clinical practice [...].

Coronary microvascular disease in women: epidemiology, mechanisms, evaluation, and treatment

Coronary microvascular dysfunction (CMD) involves functional or structural abnormalities of the coronary microvasculature resulting in dysregulation of coronary blood flow (CBF) in response to myocardial oxygen demand. This perfusion mismatch causes myocardial ischemia, which manifests in patients as microvascular angina (MVA). CMD can be diagnosed non-invasively via multiple imaging techniques or invasively using coronary function testing (CFT), which assists in determining the specific mechanisms involving endothelium-independent and dependent epicardial and microcirculation domains. Unlike traditional coronary artery disease (CAD), CMD can often occur in patients without obstructive atherosclerotic epicardial disease, which can make the diagnosis of CMD difficult. Moreover, MVA due to CMD is more prevalent in women and carries increased risk of future cardiovascular events. Successful treatment of symptomatic CMD is often patient-specific risk factor and endotype targeted. This article aims to review newly identified mechanisms and novel treatment strategies for managing CMD, and outline sex-specific differences in the presentation and pathophysiology of the disease.

Methylglyoxal induces endothelial cell apoptosis and coronary microvascular dysfunction through regulating AR-cPLA2 signaling

OBJECTIVE

Since diabetic patients with coronary microvascular dysfunction (CMD) exhibit high cardiac mortality and women have higher prevalence of non-obstructive coronary artery disease than men, we tried to expand the limited understanding about the etiology and the sex difference of diabetic CMD.

APPROACH AND RESULTS

Accumulated methylglyoxal (MGO) due to diabetes promotes vascular damage and it was used for mimicking diabetic status. Flow cytometry analysis and isometric tension measurement were performed to evaluate coronary artery endothelial injury. MGO induced apoptosis of coronary endothelial cells, accompanied by downregulation of androgen receptor (AR). Lentivirus-mediated stable expression of AR in coronary endothelial cells increased anti-apoptotic Bcl-2 expression and attenuated MGO-induced cell apoptosis. cPLA2 activation was the downstream of AR downregulation by MGO treatment. Moreover, MGO also activated cPLA2 rapidly to impair endothelium-dependent vasodilation of coronary arteries from mice. Reactive oxygen species (ROS) overproduction was demonstrated to account for MGO-mediated cPLA2 activation and endothelial dysfunction. Importantly, AR blockade increased endothelial ROS production whereas AR activation protected coronary artery endothelial vasodilatory function from the MGO-induced injury. Although galectin-3 upregulation was confirmed by siRNA knockdown in endothelial cells not to participate in MGO-induced endothelial apoptosis, pharmacological inhibitor of galectin-3 further enhanced MGO-triggered ROS generation and coronary artery endothelial impairment.

CONCLUSIONS

Our data proposed the AR downregulation-ROS overproduction-cPLA2 activation pathway as one of the mechanisms underlying diabetic CMD and postulated a possible reason for the sex difference of CMD-related angina. Meanwhile, MGO-induced galectin-3 activation played a compensatory role against coronary endothelial dysfunction.

Patients With Nonobstructive Coronary Artery Disease and Chest Pain: Impact of Obesity and Depressive Symptoms

BACKGROUND

Chest pain (CP) in patients with nonobstructive coronary artery disease is a therapeutic challenge affecting morbidity and mortality. We aimed to identify clinical factors associated with CP in this population, hypothesizing that obesity and depressive symptoms are associated with CP.

METHODS AND RESULTS

In 814 patients with angiographically confirmed nonobstructive coronary artery disease, we measured sociodemographic variables, clinical risk factors, medications, and Patient Health Questionnaire 9 scores for depressive symptoms. We assessed CP frequency and prevalence by using all items from the Seattle Angina Questionnaire angina frequency domain to generate an angina frequency composite score. In the overall sample (58.8±11.7 years old, 52.6% female), 42.8% had obesity, and 71.5% had CP, with an angina frequency composite score (SD) score of 76.4 (22.1). Compared with individuals without obesity, individuals with obesity had a higher prevalence (77.6% versus 67%, P<0.001) and more frequent CP (angina frequency composite score, 74.9 [SD, 22.2] versus 78.3 [SD, 21.9], P=0.02). Obesity was independently associated with CP occurrence (odds ratio [OR], 1.7 [95% CI, 1-2.9], P=0.04). Obesity's connection with CP was only in men: men with obesity had more frequent CP (angina frequency composite score, 75.8 [SD, 20.1] versus 82.1 [SD, 19.9], P=0.002) and more prevalent CP (79.5% versus 58.2%, P<0.001) than their counterparts insofar as men with obesity had similar CP to women. Patient Health Questionnaire 9 score (OR, 1.07 [95% CI, 1.01-1.13], P=0.03) was independently associated with CP and partly mediated the association between obesity and CP.

CONCLUSIONS

Obesity and depressive symptoms were independently associated with CP in individuals with nonobstructive coronary artery disease, particularly in men, and depressive symptoms partly mediated this association.

Pathogenesis, Assessment, and Treatment of Coronary Microcirculation Dysfunction

Cardiovascular disease is the predominant cause of mortality on a global scale. Research indicates that women exhibit a greater likelihood of presenting with non-obstructive coronary artery disease (CAD) when experiencing symptoms of myocardial ischemia in comparison to men. Additionally, women tend to experience a higher burden of symptoms relative to men, and despite the presence of ischemic heart disease, they are frequently reassured erroneously due to the absence of obstructive CAD. In cases of ischemic heart disease accompanied by symptoms of myocardial ischemia but lacking obstructive CAD, it is imperative to consider coronary microvascular dysfunction as a potential underlying cause. Coronary microvascular dysfunction, characterized by impaired coronary flow reserve resulting from functional and/or structural abnormalities in the microcirculation, is linked to adverse cardiovascular outcomes. Lifestyle modifications and the use of anti-atherosclerotic and anti-anginal medications may offer potential benefits, although further clinical trials are necessary to inform treatment strategies. This review aims to explore the prevalence, underlying mechanisms, diagnostic approaches, and therapeutic interventions for coronary microvascular dysfunction.

Association of postsystolic shortening on stress echocardiography and significant coronary artery stenosis: A single-centre retrospective cohort study

BACKGROUND

Postsystolic shortening (PSS) is one of the proposed quantitative measures to predict myocardial ischaemia in the stress echocardiographic (SE) evaluation. It is previously known that hypo-/akinesia (HA) correlates well with coronary stenosis. However, some patients undergoing SE only present with PSS, and their risk of significant coronary stenosis is less clear. This study aimed to evaluate the association between PSS and significant coronary stenosis compared with HA.

METHODS

This was a retrospective cohort study at the hospital of S:t Görans, Stockholm, Sweden. All patients who underwent SE to investigate inducible ischaemia between 1 January 2018 and 15 October 2021 were eligible for inclusion. Exclusion criteria were normal SE and inconclusive test. Pathological SE were divided into two groups, patients with HA and those with PSS. Outcome was significant coronary artery stenosis visualized by invasive coronary angiography.

RESULTS

The final study population consisted of 108 patients (73 PSS, 35 HA). The presence of HA was associated with a higher risk of significant stenosis compared to those with PSS (63% vs. 23%, p < 0.001). This relationship was observed among males (p < 0.001), but not among females (p = 0.133). Nonsignificant stenosis trended to be more common among patients with PSS (21% vs. 6%, p = 0.053) CONCLUSIONS: The finding of PSS without HA was associated with a lower risk of significant coronary stenosis than HA. However, patients with PSS still often had nonsignificant coronary stenosis and PSS in the evaluation for nonobstructive coronary artery disease (CAD) should be further investigated.

Prevalence of Coronary Microvascular Dysfunction and Epicardial Spasm in Patients With Angina and Myocardial Bridge

Background

Myocardial bridges (MB) are prevalent but not universally associated with angina. The mechanisms linking MB and angina are poorly defined. The objective of this study was to determine the prevalence of epicardial spasm, microvascular spasm, and/or endothelium-independent coronary microvascular dysfunction (CMD) in patients with MB which might explain symptoms.

Methods

Patients with known MB and chest pain at the University of Chicago Medical Center between 2020-2023 were included. All patients underwent dobutamine testing with measurement of resting full-cycle ratio to determine hemodynamic significance (resting full-cycle ratio ≤0.76). Endothelium-independent CMD was defined as coronary flow reserve <2.0 or index of microvascular resistance ≥25 on adenosine testing. Microvascular spasm was defined as chest pain and electrocardiogram changes with nonischemic fractional flow reserve with acetylcholine. Epicardial spasm was defined as dynamic stenosis of >90% of the epicardial vessel or ischemic fractional flow reserve (≤0.8) with acetylcholine.

Results

A total of 30 patients (mean age, 47 ± 10 years; 60% female) with MB were studied. Endothelium-independent CMD, microvascular spasm, and epicardial spasm occurred commonly in 60%, 29%, and 37% of patients respectively, with 77% having at least one abnormality. The MB was hemodynamically significant in 47% of patients, and the prevalence of these coexisting conditions was not affected by hemodynamic significance.

Conclusions

Epicardial spasm, microvascular spasm, and endothelium-independent CMD are prevalent in patients presenting with known MB and chest pain irrespective of the hemodynamic significance of the bridge. Invasive coronary function testing may play an important role in uncovering alternative explanations for angina in patients with known MB.

Changes in absolute coronary flow and microvascular resistance during exercise in patients with ANOCA

BACKGROUND

Whether saline-induced hyperaemia captures exercise-induced coronary flow regulation remains unknown.

AIMS

Through this study, we aimed to describe absolute coronary flow (Q) and microvascular resistance (Rμ) adaptation during exercise in participants with angina with non-obstructive coronary artery disease (ANOCA) and to explore the correlations between saline- and exercise-derived coronary flow reserve (CFR) and microvascular resistance reserve (MRR).

METHODS

Rμ, Q, CFR and MRR were assessed in the left anterior descending artery using continuous thermodilution with saline infusion at 10 mL/min (rest), 20 mL/min (hyperaemia) and finally at a 10 mL/min infusion rate during stress testing with a dedicated supine cycling ergometer. An incremental workload of 30 watts every two minutes was applied. A saline-derived CFR (CFRsaline) cutoff <2.5 was used to identify coronary microvascular dysfunction (CMD).

RESULTS

CFRsaline-defined CMD was observed in 53.3% of the participants (16/30). While cycling, these patients less of an ability to increase Q (7 [interquartile range [IQR] 30.5-103.0] vs 21 [IQR 5.8-45.0] mL/min/30 watts; p=0.01) due to a smaller decrease of Rμ (109 {IQR 32-286} vs 202 [IQR 102-379] Wood units [WU]/30 watts; p<0.01) as compared with the group with normal CFRsaline. In the overall population, CFRsaline and exercise-derived CFR (CFRexercise) were 2.70±0.90 and 2.85±1.54, respectively, with an agreement classification of 83.3%. A good correlation between saline and exercise techniques for both CFR (r=0.73; p<0.0001) and MRR (r=0.76; p<0.0001) was observed. Among participants with normal CFRsaline, 28.7% (4/14) had an impaired CFRexercise <2.5 at the peak of exercise due to a moderate and late decrease of Rμ.

CONCLUSIONS

Saline-induced hyperaemia provided a valid surrogate for exercise physiology independently of the absolute level of CFR and MRR, although exercise provided more granularity to evaluate adaptation among participants with exercise-related CMD.

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.

Prognostic Implications of Resistive Reserve Ratio in Patients With Nonobstructive Coronary Artery Disease With Myocardial Bridging

BACKGROUND

Myocardial bridging (MB) is accompanied by the dynamic extravascular compression of epicardial coronary arteries, leading to intracoronary hemodynamic disturbance with abnormal coronary flow profiles. We aimed to evaluate the prognostic implications of resistive reserve ratio (RRR), a composite measure of flow and pressure parameters that represents the vasodilatory capacity of the coronary arteries, in patients with angina with nonobstructive coronary artery disease (ANOCA) and MB, in comparison with coronary flow reserve (CFR).

METHODS AND RESULTS

In this retrospective cohort study, we included patients with ANOCA who underwent coronary reactivity testing, where MB was identified by transient constriction in coronary artery segments between systole and diastole. Abnormal CFR and RRR were defined as <2.5 and <2.62, respectively. Major adverse cardiac events, including cardiovascular death, stroke, myocardial infarction, heart failure, and late revascularization, served as outcomes. Among 1251 patients with ANOCA, 191 (15.3%) had MB. The prevalence of abnormal CFR or RRR was not significantly different between patients with and without MB (P=0.144 and P=0.398, respectively). Over a median follow-up time of 6.9 years, abnormal RRR predicted major adverse cardiac events in patients with MB (hazard ratio [HR], 4.38 [95% CI, 1.71-11.21]; P=0.002) and without MB (HR, 1.91 [95% CI, 1.38-2.64]; P<0.001). Abnormal CFR predicted major adverse cardiac events in patients without MB (HR, 2.15 [95% CI, 1.54-3.00]; P<0.001), whereas it was not predictive of major adverse cardiac events in patients with MB (HR, 2.29 [95% CI, 0.93-5.65]; P=0.073).

CONCLUSIONS

In patients with ANOCA and MB, impaired RRR was superior to impaired CFR in distinguishing patients at a higher risk of future adverse events, suggesting that RRR may serve as a risk stratification tool in patients with MB and ANOCA.

Objective Ischemia, Subjective Angina, and Psychological Distress in Angina With No Obstructive Coronary Disease

BACKGROUND

Angina with no obstructive coronary disease (ANOCA) and ischemia with no obstructive coronary disease, prevalent yet underrecognized conditions, mostly affect women. Previous studies rarely distinguished between them. We aimed to compare the prevalence of objective ischemia through various examinations in women with ANOCA and assess the impact of objective and subjective ischemia on their mental health.

METHODS AND RESULTS

A total of 84 eligible women with ANOCA and 42 controls underwent mental stress, pharmacological stress, exercise stress, and Holter testing. Objective evidence of myocardial ischemia was assessed by positron emission tomography-computed tomography and ECG, and subjective symptoms were graded using the Canadian Cardiovascular Society scale (CCS). Psychological assessments were conducted using 6 scales. Among 84 women with ANOCA, 37 (44%) received a diagnosis of ischemia with no obstructive coronary disease following mental stress testing, 20 (28.6%) through pharmacological stress testing, 14 (21.2%) via exercise stress testing, and 24 (32.9%) from Holter. Mental stress-induced myocardial ischemia was more prevalent (P<0.05). Among 54 patients with ANOCA who completed all tests, 30% showed no ischemia, and only 1 (1.9%) showed ischemia in all tests. In addition, patients with ANOCA had higher psychological scores than controls (P<0.01). No significant differences was observed in psychological scores between ANOCA with positive and negative ischemia test results (P>0.05). However, ANOCA with milder angina (CCS I) exhibited higher scores across the Hospital Anxiety and Depression Scale, State-Trait Anxiety Inventory, Perceived Stress Scale, and Posttraumatic Stress Disorder Checklist-Civilian Version and a higher prevalence of Type D personality traits (P<0.05).

CONCLUSIONS

In patients with ANOCA, the positive rate of myocardial ischemia exhibits variability among several noninvasive tests. A worsened psychological state is more closely linked to milder angina symptoms than to ischemia performance, highlighting the importance of focusing on symptom management in their psychological care.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03982901.

Epicardial adipose tissue attenuation on computed tomography in women with coronary microvascular dysfunction: A pilot, hypothesis generating study

BACKGROUND

Patients with myocardial ischemia without obstructive coronary artery disease often have coronary microvascular dysfunction (CMD) and associated increased risk of cardiovascular (CV) events and anginal hospitalizations. Epicardial adipose tissue (EAT) covers much of the myocardium and coronary arteries and when dysfunctional, secretes proinflammatory cytokines and is associated with CV events. While oxidative stress and systemic inflammation are associated with CMD, the relationship between EAT and CMD in women is not well known.

METHODS

Women diagnosed with CMD (n = 21) who underwent coronary computed tomography with coronary artery calcium (CAC) scoring were compared to a reference group (RG) of women referred for CAC screening for preventive risk assessment (n = 181). EAT attenuation (Hounsfield units (HU)) was measured adjacent to the proximal right coronary artery, along with subcutaneous adipose tissue (SCAT). Two-sample t-tests with unequal variances were utilized.

RESULTS

Mean age of the CMD group was 56 ± 8 years and body mass index (BMI) was 31.6 ± 6.8 kg/m2. CV risk factors in the CMD group were prevalent: 67 % hypertension, 44 % hyperlipidemia, and 33 % diabetes. Both CMD and RG had similar CAC score (25.86 ± 59.54 vs. 24.17 ± 104.6; p = 0.21. In the CMD group, 67 % had a CAC of 0. Minimal atherosclerosis (CAD-RADS 1) was present in 76 % of women with CMD. The CMD group had lower EAT attenuation than RG (-103.3 ± 6.33 HU vs. -97.9 ± 8.3 HU, p = 0.009, respectively). There were no differences in SCAT attenuation. Hypertension, smoking history, age, BMI, and CAC score did not correlate with EAT in either of the groups.

CONCLUSIONS

Women with CMD have decreased EAT attenuation compared to RG women. EAT-mediated inflammation and changes in vascular tone may be a mechanistic contributor to abnormal microvascular reactivity. Clinical trials testing therapeutic strategies to decrease EAT may be warranted in the management of CMD.

Beyond Coronary Artery Disease: Assessing the Microcirculation

Ischemic heart disease (IHD) affects more than 20 million adults in the United States. Although classically attributed to atherosclerosis of the epicardial coronary arteries, nearly half of patients with stable angina and IHD who undergo invasive coronary angiography do not have obstructive epicardial coronary artery disease. Ischemia with nonobstructive coronary arteries is frequently caused by microvascular angina with underlying coronary microvascular dysfunction (CMD). Greater understanding the pathophysiology, diagnosis, and treatment of CMD holds promise to improve clinical outcomes of patients with ischemic heart disease.

Safety and Effectiveness of Coronary Sinus Reducer in the Therapy of Refractory Angina Pectoris-Mid-Term Results of the Real-Life Cohort

Background: Despite continuous improvements in revascularization techniques, refractory angina without potential revascularization options remains a relevant clinical issue with significant impact on the patient's quality of life. Recently, a novel device, the Coronary Sinus Reducer (CSR), has been introduced into clinical practice as a therapeutic option for patients with disabling angina pectoris. In this single-center, observational study, we evaluated the mid-term (3-month) safety and efficacy of the CSR in a real-world cohort. Methods: The study population consisted of 55 patients with refractory angina without potential revascularization options, who were predominantly men (87.3%) with a high cardiovascular risk factor burden and advanced angina (baseline CCS angina class 3.15 ± 0.6). In terms of procedure safety, all patients underwent successful device deployment with only one periprocedural complication. Results: At the 3-month follow-up, we observed a statistically significant improvement in angina control measured CCS class and SAQ-7 total questionnaire along with increased abolition of physical limitation-6-MWT (233.3 ± 107.1 vs. 305.2 ± 126.8; p < 0.0001). Additionally, we observed significant improvement in terms of quality of life measurements SF-36, the EQ-5D-5L questionnaire, and the EQ-VAS. Conclusions: Our real-world data suggest that CSR implantation is a relatively safe procedure and appears to be particularly effective in relieving angina symptoms and improving quality of life in subjects with refractory angina.

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.

Unstable Angina Risk Stratification Using High-Sensitivity Cardiac Troponin and Coronary Angiography

Patients formerly diagnosed with unstable angina (UA) are being reclassified as non-ST-elevation myocardial infarction with the widespread adoption of high-sensitivity troponin (hsTn) assays, leading to significant changes in the incidence and prognosis of UA. This study aimed to evaluate the value of hsTn and the presence of significant obstructive coronary artery disease (CAD) in the risk stratification of patients with UA. We conducted a retrospective, single-center study of 742 patients hospitalized for UA between 2016 and 2021. The primary end point of this study was all-cause mortality. The secondary outcome (major adverse cardiac events [MACEs]) was defined as a composite of nonfatal myocardial infarction (MI), hospitalization for heart failure (hHF), and repeated coronary angiography because of recurring UA (rUA) after the index event. The outcomes were assessed within 1 month, 1 year, and up to 5 years of follow-up. The average follow-up duration was 45 ± 24 months, and 37.2% (n = 276) of patients completed a 5-year follow-up. No in-hospital death was observed, and 6.9% of patients died during follow-up, which was more commonly a late event (>12 months). The composite secondary end point (MI+hHF+rUA) was observed in 16.7% of the patients. There were 3.2% nonfatal MI, 2.3% hHF, and 11.6% rUA during follow-up. We developed a risk model (UA mortality risk) using variables with the highest discriminatory power: age, hsTn, and ST-segment deviation. Our model performed well against the Global Registry of Acute Coronary Events and Thrombolysis in Myocardial Infarction risk scores in predicting death during follow-up. Obstructive CAD on coronary angiography was the only independent predictor of MACEs during follow-up. In conclusion, a contemporary cohort of patients with UA presented with favorable prognosis, particularly, within the first year after the index event. Nonsignificant increases in hsTn levels add to the risk stratification of patients with UA, and the presence of obstructive CAD was the only independent predictor of MACEs, highlighting the potential importance of assessing coronary anatomy.

The pressure-derived microvascular resistance reserve and its correlation to Doppler MRR measurement-a proof of concept study

Background

Microvascular resistance reserve (MRR) is a recently introduced specific index of coronary microcirculation. MRR calculation can utilize parameters deriving from coronary flow reserve (CFR) assessment, provided that intracoronary pressure data are also available. The previously proposed pressure-bounded CFR (CFRpb) defines the possible CFR interval on the basis of resting and hyperemic pressure gradients in the epicardial vessel, however, its correlation to the Doppler wire measurement was reported to be rather poor without the correction for hydrostatic pressure.

Purpose

We aimed to determine the pressure-bounded coronary MRR interval with hydrostatic pressure correction according to the previously established equations of CFRpb adapted for the MRR concept. Furthermore, we also aimed to design a prediction model using the actual MRR value within the pressure-bounded interval and validate the results against the gold-standard Doppler wire technique.

Methods

Hydrostatic pressure between the tip of the catheter and the sensor of the pressure wire was calculated by height difference measurement from a lateral angiographic view. In the derivation cohort the pressure-bounded MRR interval (between MRRpbmin and MRRpbmax) was determined solely from hydrostatic pressure-corrected intracoronary pressure data. The actual MRR was calculated by simple hemodynamic equations incorporating the anatomical data of the three-dimensionally reconstructed coronary artery (MRRp-3D). These results were analyzed by regression analyses to find relations between the MRRpb bounds and the actual MRRp-3D.

Results

In the derivation cohort of 23 measurements, linear regression analysis showed a tight relation between MRRpbmax and MRRp-3D (r 2 = 0.74, p < 0.0001). Using this relation (MRRp-3D = 1.04 + 0.51 × MRRpbmax), the linear prediction of the MRR was tested in the validation cohort of 19 measurements against the gold standard Doppler wire technique. A significant correlation was found between the linearly predicted and the measured values (r = 0.54, p = 0.01). If the area stenosis (AS%) was included to a quadratic prediction model, the correlation was improved (r = 0.63, p = 0.004).

Conclusions

The MRR can be predicted reliably to assess microvascular function by our simple model. After the correction for hydrostatic pressure error, the pressure data during routine FFR measurement provides a simultaneous physiological assessment of the macro- and microvasculature.

Transthoracic ultrasound localization microscopy of myocardial vasculature in patients

Myocardial microvasculature and haemodynamics are indicative of potential microvascular diseases for patients with symptoms of coronary heart disease in the absence of obstructive coronary arteries. However, imaging microvascular structure and flow within the myocardium is challenging owing to the small size of the vessels and the constant movement of the patient's heart. Here we show the feasibility of transthoracic ultrasound localization microscopy for imaging myocardial microvasculature and haemodynamics in explanted pig hearts and in patients in vivo. Through a customized data-acquisition and processing pipeline with a cardiac phased-array probe, we leveraged motion correction and tracking to reconstruct the dynamics of microcirculation. For four patients, two of whom had impaired myocardial function, we obtained super-resolution images of myocardial vascular structure and flow using data acquired within a breath hold. Myocardial ultrasound localization microscopy may facilitate the understanding of myocardial microcirculation and the management of patients with cardiac microvascular diseases.

Smoking and Respiratory Diseases in Patients with Coronary Microvascular Dysfunction

BACKGROUND

Coronary microvascular disease (CMD) is common in patients with and without obstructive coronary artery disease, and is associated with adverse clinical outcomes. Respiratory-related variables are associated with pulmonary and systemic microvascular dysfunction, while evidence about their relationship with CMD is limited. We aim to evaluate respiratory-related variables as risk factors of CMD.

METHODS

This is an observational, single-center study enrolling consecutive patients undergoing invasive evaluation of coronary microvascular function in the catheterization laboratory. Patients with evidence of obstructive coronary artery disease or with missing data were excluded. Associations between respiratory-related variables and indices of CMD were assessed using univariate and multivariate regression models.

RESULTS

Overall, 266 patients (mean age 67 ± 11 years, 59% females) were included in the current analysis. Of those, 155 (58%) had evidence of CMD. Among the respiratory variables, independent predictors of CMD were current smoking (adjusted odds ratio [AOR] 2.5; 95% confidence interval [CI], 1.2-5; P = .01) and obstructive sleep apnea (AOR 5.7; 95% CI, 1.2-26; P = .03), while chronic obstructive pulmonary disease was not. Among ever-smokers, higher smoking pack-years was an independent risk factor for CMD (median 35 vs 25 pack-years, AOR 1.09; 95% CI, 1.04-1.13; P < .01), and was associated with higher rates of pathologic index of microcirculatory resistance and resistive reserve ratio.

CONCLUSION

In patients undergoing invasive coronary microvascular evaluation, current smoking and obstructive sleep apnea are independently associated with CMD. Among smokers, higher pack-years is a strong predictor for CMD. Our findings should raise awareness for prevention and possible treatment options.

INOCA: Ischemia in non-obstructive coronary arteries

This article provides a summary of the clinical spectrum of no obstructive coronary arteries. We describe the pathologies, invasive and noninvasive assessment, and management strategies.