Cardiac magnetic resonance myocardial perfusion reserve index is reduced in women with coronary microvascular dysfunction. A National Heart, Lung, and Blood Institute-sponsored study from the Women's Ischemia Syndrome Evaluation

Contributors to high left ventricular ejection fraction in women with ischemia and no obstructive coronary artery disease: Results from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) Study

BACKGROUND

There are sex differences in left ventricular ejection fraction (LVEF) relevant to prognosis where women experience greater mortality at relatively higher LVEF compared to men, yet mechanistic understanding of this adverse prognosis is limited. Women with suspected ischemia with no obstructive coronary disease (INOCA) develop heart failure with preserved ejection fraction (HFpEF), yet contributors to LVEF remain largely unknown.

METHODS

In 370 women with suspected ischemia with no obstructive coronary disease (INOCA) who prospectively underwent cardiac magnetic resonance imaging (CMRI), we investigated the contributions of LV morphology, function, and myocardial perfusion reserve on LVEF using univariate and multiple linear regression.

RESULTS

A majority 71% of participants had high LVEF (>65%), followed by 24% having normal LVEF (55%-65%), and only 5% having low EF (<55%). Baseline characteristics were comparable among the 3 groups, with the exception of age which was 6 years higher in the high LVEF group (P < .01). Women in the high LVEF group also had the lowest LV cavity volume, greatest LV mass-volume ratio, and highest LV end-systolic elastance (all P < .05, adjusted for age, BMI, diabetes, and blood pressure). Myocardial perfusion reserve index was low in all groups (mean MPRI < 2.1) but was not significantly different across the spectrum of LVEF (P = .458).

CONCLUSIONS

Taken together, these data demonstrate that the majority of women with suspected INOCA have elevated LVEF related to smaller, thicker ventricles with greater contractility. Future work is needed to better understand the specific mechanisms driving morphologic and functional changes in women with INOCA, and relations to longer-term HFpEF and mortality.

CLINICAL TRIALS REGISTRATION

NCT02582021.

Coronary Microvascular Dysfunction: Searching the Strongest Imaging Modality in Different Scenarios

Coronary microvascular dysfunction is a clinical condition very diffuse in many different settings. Often the diagnosis can be very tricky, and choosing the proper diagnostic strategy can be fundamental for reaching the goal. The aim of this review is to evaluate the properties and the feasibility of our tests in specific scenarios by looking at the performances of each methodology reported in the literature.

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.

Ischemia with non-obstructive coronary artery (INOCA): Non-invasive versus invasive techniques for diagnosis and the role of #FullPhysiology

Ischemia with non-obstructive coronary arteries (INOCA) is an increasingly recognized entity. It encompasses different pathophysiological subtypes (i.e., endotypes), including coronary microvascular dysfunction (CMD), vasospastic angina (VSA) and mixed entities resulting from the variable combination of both. Diagnosing INOCA and precisely characterizing the endotype allows for accurate medical treatment and has proven prognostic implications. A breadth of diagnostic technique is available, ranging from non-invasive approaches to invasive coronary angiography adjuvated by functional assessment and provocative tests. This review summarizes the strength and limitations of these methodologies and provides the rationale for the routine referral for invasive angiography and functional assessment in this subset of patients.

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.

Coronary microvascular dysfunction in autoimmune rheumatic diseases: beyond coronary flow velocity reserve

Autoimmune rheumatic diseases (ARDs) are a heterogeneous group of disorders characterized by an inappropriate immune reactivity against different body tissues. Patients affected by ARDs present increased cardiovascular morbidity and mortality, which significantly impacts long-term prognosis. Endothelial dysfunction, inflammation, oxidative stress, and autoimmunity are strictly involved in atherosclerosis progression and coronary microvascular dysfunction (CMD), both of which contribute to increased cardiovascular risk. CMD represents the inability of the coronary microvasculature to respond with vasodilation to increased cardiac metabolic demands and can be assessed by non-invasive and invasive imaging tests. Coronary flow velocity reserve assessed by echocardiography has been demonstrated to accurately identify ARDs patients with CMD. However, stress cardiac magnetic resonance (CMR) accurately assesses myocardial ischemia, perfusion, and viability in ARDs patients. The myocardial perfusion reserve index (MPRI) is a robust semiquantitative imaging marker that represents the vasodilatory capacity of the coronary microcirculation in response to a vasodilator stress. In the absence of significant coronary stenosis, ARDs patients revealed a reduced MPRI in comparison with the general population, regardless of the presence of myocardial fibrosis. Identification of CMD in asymptomatic patients could be crucial to precociously start targeted medical therapy, avoiding major adverse cardiac events in this clinical setting. This review aims to summarize the current evidence regarding CMD in ARDs patients, focusing on the role of stress CMR and the promising myocardial perfusion analysis.

Evaluating Ischemic Heart Disease in Women: Focus on Angina With Nonobstructive Coronary Arteries (ANOCA)

Ischemic heart disease (IHD) is common in women, and cardiovascular disease is a leading cause of morbidity and mortality. While obstructive coronary artery disease is the most common form of IHD, millions of women suffer from angina with nonobstructive coronary arteries (ANOCA), an umbrella term encompassing multiple nonatherosclerotic disorders of the coronary tree. The underlying pathology leading to ischemia in these syndromes may be challenging to diagnose, leaving many women without a diagnosis despite persistent symptoms that impact quality of life and adversely affect long-term cardiovascular prognosis. In the last decade, there have been significant advances in the recognition and diagnostic evaluation of ANOCA. Despite these advances, the standard approach to evaluating suspected IHD in women continues to focus predominantly on the assessment of atherosclerotic coronary artery disease, leading to missed opportunities to accurately diagnose and treat underlying coronary vasomotor disorders. The goal of this review is to describe advances in diagnostic testing that can be used to evaluate angina in women and present a pragmatic diagnostic algorithm to guide evaluation of ANOCA in symptomatic patients. The proposed approach for the assessment of ANOCA is consistent with prior expert consensus documents and guidelines but is predicated on the medical interview and pretest probability of disease to inform a personalized diagnostic strategy.

Coronary microvascular dysfunction in childhood: An emerging pathological entity and its clinical implications

Coronary microvascular dysfunction (CMD) encompasses a spectrum of structural and functional alterations in coronary microvasculature resulting in impaired coronary blood flow and consequent myocardial ischemia without obstruction in epicardial coronary artery. The pathogenesis of CMD is complex involving both functional and structural alteration in the coronary microcirculation. In adults, CMD is predominantly discussed in context with anginal chest pain or existing ischemic heart disease and its risk factors. The presence of CMD suggests increased risk of adverse cardiovascular events independent of coronary atherosclerosis. Coronary microvascular dysfunction is also known in children but is rarely recognized due to paucity of concommitent coronary artery disease. Thus, its clinical presentation, underlying mechanism of impaired microcirculation, and prognostic significance are poorly understood. In this review article, we will overview variable CMD reported in children and delineate its emerging clinical significance.

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.

Arterial stiffness assessment in coronary microvascular dysfunction and heart failure with preserved ejection fraction: An initial report from the WISE-CVD continuation study

Background

Heart failure with preserved ejection fraction (HFpEF) is the most common cardiac complication in patients with coronary microvascular dysfunction (CMD), yet its underlying pathways remain unclear. Aortic pulse-wave velocity (aPWV) is an indicator of large artery stiffness and a predictor for cardiovascular disease. However, aPWV in CMD and HFpEF is not well characterized and may provide understanding of disease progression.

Methods

Among participants without obstructive coronary artery disease, we evaluated 51 women with suspected CMD and 20 women and men with evidence of HFpEF. All participants underwent aPWV measurement (SphygmoCor, Atcor Medical) with higher aPWV indicating greater vascular stiffness. Cardiac magnetic resonance imaging (CMRI) assessed left ventricular (LV) ejection fraction, CMD via myocardial perfusion reserve index (MPRI), and ventricular remodeling via LV mass-volume ratio. . Statistical analysis was performed using Wilcoxon rank sum tests, Pearson correlations and linear regression analysis.

Results

Compared to the suspected CMD group, the HFpEF participants were older (65 ± 12 vs 56 ± 11 yrs., p = 0.002) had higher BMI (31.0 ± 4.3 vs 27.8 ± 6.7 kg/m2, p = 0.013), higher aPWV (10.5 ± 2.0 vs 8.0 ± 1.6 m/s, p = 0.05) and lower MPRI (1.5 ± 0.3 vs1.8 ± 0.3, p = 0.02), but not remodeling. In a model adjusted for cardiovascular risk factors, the HFpEF group had a lower LVEF (estimate -4.78, p = 0.0437) than the suspected CMD group.

Conclusions

HFpEF participants exhibit greater arterial stiffness and lower myocardial perfusion reserve, with lower LVEF albeit not remodeling, compared to suspected CMD participants. These findings suggest arterial stiffness may contribute to progression from CMD to HFpEF. Prospective work is needed and ongoing.

Pericardial fat volume is related to endothelial-mediated coronary blood flow in women with suspected coronary microvascular dysfunction. A report from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study

Background

Coronary microvascular dysfunction is prevalent in women with signs and symptoms of ischemia but no obstructive coronary artery disease (CAD) and is associated with an adverse prognosis. Elevated pericardial fat volume predicts adverse cardiac events, but mechanistic pathways of the association are not well understood.

Methods

118 women enrolled in the NHLBI-sponsored Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction study with suspected coronary microvascular dysfunction but no obstructive CAD underwent adenosine stress 1.5 T cardiovascular magnetic resonance imaging (CMR) imaging and invasive coronary reactivity testing. Semi-quantitative myocardial perfusion reserve index (MPR) index was derived from perfusion images. Pericardial fat volume was measured by manually contouring the cardiac margins and adjacent adipose tissue on a single trans-axial HASTE slice at the level of the left main coronary artery origin and indexed to body surface-area. Simple standard deviation analysis obtained for continuous variables and frequency (percent) for categorical variables. The relationships between pericardial fat volume and coronary reactivity testing parameters were examined by correlation and multivariable regression analyses.

Results

Women with suspected coronary microvascular dysfunction had a mean age of 55 ± 10 years, body mass index (BMI) of 28 ± 7 kg/m2, 44 % had a history of smoking, 63 % hypertension, 8 % diabetes, and 20 % dyslipidemia. CMR imaging-derived pericardial fat volume and coronary blood flow response to intracoronary acetylcholine (Δ CBF) were negatively correlated (r = -0.32, p = 0.0013). After adjustment for age, number of risk factors, high-density lipoprotein (HDL), and cold pressor diameter response, pericardial fat volume remained a significant predictor of Δ coronary blood flow (p = 0.04). There was no association with other coronary reactivity testing measures or CMRI derived MPR index.

Conclusions

Among women with suspected coronary microvascular dysfunction but no obstructive CAD, pericardial fat volume appears to be related in a hypothesized adverse direction to coronary microvascular endothelial function. These results support further work confirming and extending these results to investigate pericardial fat volume as mechanistic pathway and potential treatment target for coronary microvascular dysfunction-related adverse events.Trial registration: clinicaltrials.govNCT00832702.

Cardiovascular multimodality imaging in women: a scientific statement of the European Association of Cardiovascular Imaging of the European Society of Cardiology

Cardiovascular diseases (CVD) represent an important cause of mortality and morbidity in women. It is now recognized that there are sex differences regarding the prevalence and the clinical significance of the traditional cardiovascular (CV) risk factors as well as the pathology underlying a range of CVDs. Unfortunately, women have been under-represented in most CVD imaging studies and trials regarding diagnosis, prognosis, and therapeutics. There is therefore a clear need for further investigation of how CVD affects women along their life span. Multimodality CV imaging plays a key role in the diagnosis of CVD in women as well as in prognosis, decision-making, and monitoring of therapeutics and interventions. However, multimodality imaging in women requires specific consideration given the differences in CVD between the sexes. These differences relate to physiological changes that only women experience (e.g. pregnancy and menopause) as well as variation in the underlying pathophysiology of CVD and also differences in the prevalence of certain conditions such as connective tissue disorders, Takotsubo, and spontaneous coronary artery dissection, which are all more common in women. This scientific statement on CV multimodality in women, an initiative of the European Association of Cardiovascular Imaging of the European Society of Cardiology, reviews the role of multimodality CV imaging in the diagnosis, management, and risk stratification of CVD, as well as highlights important gaps in our knowledge that require further investigation.

The Role of Coronary Physiology Assessment in the Diagnosis and Treatment of Stable Angina. Dive Inside Recent Findings of Diffuse Coronary Disease Treatment

Coronary physiology is widely used to assess epicardial coronary lesions in patients with stable angina. Based on the available evidence, physiology plays a crucial role in diagnosing and treating patients. There have been invasive methods for determining cardiac physiology, such as fractional flow reserve and instantaneous wave-free ratio. Still, new non-invasive approaches provide extra anatomical information, such as fractional flow reserve computed tomography (FFR-CT) based on computed tomography and physiology based on angiography. Even though FFR-guided percutaneous coronary intervention (PCI) is clinically beneficial, one-third of patients retain suboptimal FFR after the procedure, associated with severe adverse events, rendering PCI in diffuse coronary artery disease questionable. Using the pullback pressure gradient (PPG), we can analyze the magnitude and extent of pressure losses; a lower value may indicate diffuse disease, while a high value with an abrupt curve may indicate focal disease. Since PCI is not the best option for treating diffuse coronary disease, current strategies focus on conservatively using medical therapy or bypass surgery. It has been demonstrated that patients with diffuse disease of the left anterior descending (LAD) are at a greater risk of developing occlusion of the left internal mammary artery graft than those with focal disease and that maximal medical therapy may be the most effective treatment for these patients.

Ischemia but no obstructive coronary artery disease: more than meets the eye

Symptomatic women with angina are more likely to have ischemia with no obstructive coronary arteries (INOCA) compared to men. In both men and women, the finding of INOCA is not benign and is associated with adverse cardiovascular events, including myocardial infarction, heart failure and angina hospitalizations. Women with INOCA have more angina and a lower quality of life compared to men, but they are often falsely reassured because of a lack of obstructive coronary artery disease (CAD) and a perception of low risk. Coronary microvascular dysfunction (CMD) is a key pathophysiologic contributor to INOCA, and non-invasive imaging methods are used to detect impaired microvascular flow. Coronary vasospasm is another mechanism of INOCA, and can co-exist with CMD, but usually requires invasive coronary function testing (CFT) with provocation testing for a definitive diagnosis. In addition to traditional heart disease risk factors, inflammatory, hormonal and psychological risk factors that impact microvascular tone are implicated in INOCA. Treatment of risk factors and use of anti-atherosclerotic and anti-anginal medications offer benefit. Increasing awareness and early referral to specialized centers that focus on INOCA management can improve patient-oriented outcomes. However, large, randomized treatment trials to investigate the impact on major adverse cardiovascular events (MACE) are needed. In this focused review, we discuss the prevalence, pathophysiology, presentation, diagnosis and treatment of INOCA.

The diagnosis and treatment of women with recurrent cardiac ischemia and normal coronary arteries

Cardiac disease is the leading cause of death in women. Among women with recurrent chest pain, abnormal electrocardiograms, and/or stress tests who undergo coronary angiography, as many as 50% have normal or <50% coronary artery obstructive disease. Pharmacologic stress assessment of coronary artery flow reserve in these women frequently demonstrates an inability to increase blood flow to >2.5 times normal flow. Contributory factors include abnormal epicardial or microvascular reactivity, microvascular remodeling or rarefaction, autonomic dysfunction, or coronary plaque rupture/erosion. Assessment is necessary of serum biomarkers and coronary artery flow reserve, fractional flow reserve, microvascular resistance, and epicardial/microvascular spasm. Aggressive treatment of women with positive tests is necessary because these women have an increased incidence of recurrent chest pain, repeated hospitalizations and coronary angiograms, and cardiac death.

Ranolazine for improving coronary microvascular function in patients with nonobstructive coronary artery disease: a systematic review and meta-analysis with a trial sequential analysis of randomized controlled trials

Background

Microvascular dysfunction in patients with nonobstructive coronary artery disease is increasingly being recognized as an important health issue. This systematic review and meta-analysis evaluated the effectiveness of ranolazine, an antianginal agent, in improving coronary microvascular function.

Methods

We conducted a comprehensive literature search of the Cochrane Library, PubMed, Embase, China National Knowledge Infrastructure, the Chinese BioMedical Literature Database, and gray literature databases until September 30, 2023. The included studies were randomized controlled trials (RCTs) published in the English or Chinese languages that screened for eligibility using two independent investigators. Risk of bias was evaluated with the Cochrane Collaboration tool. Subgroup and sensitivity analyses were used to identify sources of heterogeneity. Meta-analysis was performed using RevMan version 5.4 (Cochrane) and Stata version 16.0 (StataCorp).

Results

From 1,470 citations, 8 RCTs involving 379 participants were included in this analysis. Our findings showed that ranolazine increased coronary flow reserve (CFR) over an 8 to 12-week follow-up period [standardized mean difference =1.16; 95% confidence interval (CI): 0.4-1.89; P=0.002]. Ranolazine increased the global myocardial perfusion reserve index (MPRI) [weighted mean difference (WMD) =0.18; 95% CI: 0.07-0.29; P=0.002] and the midsubendocardial MPRI (WMD =0.10; 95% CI: 0.02-0.19; P=0.02). Moreover, ranolazine improved 3 of the 5 Seattle Angina Questionnaire scores, namely, physical functioning (WMD =4.89; 95% CI: 0.14 to 9.64; P=0.04), angina stability (WMD =17.31; 95% CI: 7.13-27.49; P=0.0009), and quality of life (WMD =10.11; 95% CI: 3.57-16.65; P=0.0003). Trial sequential analysis showed that the meta-analysis of angina stability and quality of life scores had a sufficient sample size and statistical power.

Conclusions

Our analysis suggests that ranolazine is associated with improvements in CFR, myocardial perfusion, and the Seattle Angina Questionnaire scores in patients with nonobstructive coronary artery disease. However, further large-scale RCTs with long-term follow-up are recommended to validate these findings and provide a more comprehensive understanding of the effects of ranolazine on coronary microvascular function.

Global Longitudinal Strain as Predictor of Inducible Ischemia in No Obstructive Coronary Artery Disease in the CIAO-ISCHEMIA Study

BACKGROUND

Global longitudinal strain (GLS) is a sensitive marker for identifying subclinical myocardial dysfunction in obstructive coronary artery disease (CAD). Little is known about the relationship between GLS and ischemia in patients with myocardial ischemia and no obstructive CAD (INOCA).

OBJECTIVES

To investigate the relationship between resting GLS and ischemia on stress echocardiography (SE) in patients with INOCA.

METHODS

Left ventricular GLS was calculated offline on resting SE images at enrollment (n = 144) and 1-year follow-up (n = 120) in the CIAO-ISCHEMIA (Changes in Ischemia and Angina over One year in International Study of Comparative Health Effectiveness with Medical and Invasive Approaches trial screen failures with no obstructive CAD on computed tomography [CT] angiography) study, which enrolled participants with moderate or severe ischemia by local SE interpretation (≥3 segments with new or worsening wall motion abnormality and no obstructive (<50% stenosis) on coronary computed tomography angiography.

RESULTS

Global longitudinal strain values were normal in 83.3% at enrollment and 94.2% at follow-up. Global longitudinal strain values were not associated with a positive SE at enrollment (GLS = -21.5% positive SE vs GLS = -19.9% negative SE, P = .443) or follow-up (GLS = -23.2% positive SE vs GLS = -23.1% negative SE, P = .859). Significant change in GLS was not associated with positive SE in follow-up (P = .401). Regional strain was not associated with colocalizing ischemia at enrollment or follow-up. Changes in GLS and number of ischemic segments from enrollment to follow-up showed a modest but not clinically meaningful correlation (β = 0.41; 95% CI, 0.16, 0.67; P = .002).

CONCLUSIONS

In this cohort of INOCA patients, resting GLS values were largely normal and did not associate with the presence, severity, or location of stress-induced ischemia. These findings may suggest the absence of subclinical myocardial dysfunction detectable by echocardiographic strain analysis at rest in INOCA.

Coronary Microvascular Dysfunction and Hypertension: A Bond More Important than We Think

Coronary microvascular dysfunction (CMD) is a clinical entity linked with various risk factors that significantly affect cardiac morbidity and mortality. Hypertension, one of the most important, causes both functional and structural alterations in the microvasculature, promoting the occurrence and progression of microvascular angina. Endothelial dysfunction and capillary rarefaction play the most significant role in the development of CMD among patients with hypertension. CMD is also related to several hypertension-induced morphological and functional changes in the myocardium in the subclinical and early clinical stages, including left ventricular hypertrophy, interstitial myocardial fibrosis, and diastolic dysfunction. This indicates the fact that CMD, especially if associated with hypertension, is a subclinical marker of end-organ damage and heart failure, particularly that with preserved ejection fraction. This is why it is important to search for microvascular angina in every patient with hypertension and chest pain not associated with obstructive coronary artery disease. Several highly sensitive and specific non-invasive and invasive diagnostic modalities have been developed to evaluate the presence and severity of CMD and also to investigate and guide the treatment of additional complications that can affect further prognosis. This comprehensive review provides insight into the main pathophysiological mechanisms of CMD in hypertensive patients, offering an integrated diagnostic approach as well as an overview of currently available therapeutical modalities.

Automatic calculation of myocardial perfusion reserve using deep learning with uncertainty quantification

Background

Myocardial perfusion reserve index (MPRI) in magnetic resonance imaging (MRI) is an important indicator of ischemia, and its measurement typically involves manual procedures. The purposes of this study were to develop a fully automatic method for estimating the MPRI and to evaluate its performance.

Methods

The method consisted of segmenting the myocardium in dynamic contrast-enhanced (DCE) myocardial perfusion MRI data using Monte Carlo dropout U-Net, dividing the myocardium into segments based on landmark localization with machine learning, and estimating the MPRI after the calculation of the left ventricular and myocardial contrast upslopes. The proposed method was compared with a reference method, which involved manual adjustments of the myocardial contours and upslope ranges.

Results

In test subjects, MPRIs measured by the proposed technique correlated with those by the manual reference in segmental assessment [intraclass correlation coefficient (ICC) =0.75, 95% CI: 0.70-0.79, P<0.001]. The automatic and reference MPRI values showed a mean difference of -0.02 and 95% limits of agreement of (-0.86, 0.82).

Conclusions

The proposed automatic method is based on deep learning segmentation and machine learning landmark detection for MPRI measurements in DCE perfusion MRI. It holds the potential to efficiently and quantitatively assess myocardial ischemia without any user's interaction.

Diseases of the Coronary Microcirculation: Diagnosis and Treatment

BACKGROUND

Coronary microvascular dysfunction (CMD) comprises a variety of pathogenic mechanisms that impair the microcirculation of the heart. Clinical studies have shown that 30-50% of patients suffering from myocardial ischemia without significant coronary artery stenosis have CMD. The disease is associated with ele - vated mortality and poor quality of life. Whenever a patient presents with symptoms of angina pectoris and no underlying disease is detected by the usual methods, CMD should be considered a possible cause.

METHODS

This review is based on publications retrieved by a selective search in PubMed and on current international guidelines and recommendations of specialty societies.

RESULTS

The diagnosis of CMD is based on objective evidence of a microvascular origin of symptoms. The guidelines contain a class IIa recommendation for invasive coronary flow reserve and microvascular resistance measurements. Noninvasive tests such as positron emission tomography and cardiac magnetic resonance imaging are less accurate and are given a class IIb recommendation. No highquality therapeutic trials are available to date, and the treatment of CMD is thus based on that of chronic coronary syndrome. Lifestyle modification is performed to reduce risk factors. Patients with an abnormal coronary flow reserve or elevated microvascular resistance can be treated with an ACE inhibitor or angiotensin receptor blocker. Beta-blockers and calcium channel antagonists can relieve angina pectoris. Statins lower the LDL level and have positive pleiotropic effects. First-line treatment can be supplemented with further medications.

CONCLUSION

Approximately 25% of patients with CMD have symptoms that do not respond to intensive treatment with the currently available modalities. New treatments, including interventional therapies, are being studied. Their long-term benefit remains to be assessed and compared to that of the existing methods.

Coronary microvascular dysfunction and myocardial infarction with non-obstructive coronary arteries: Where do we stand?

In the past decade, scientific and clinical research has provided a translational perspective on myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA). MINOCA is characterized by clinical documentation of an acute MI but angiography shows no significant coronary artery obstruction (stenosis <50%). The prevalence of MINOCA is estimated to range from approximately 6 to 10% among MI patients, and those with this condition have a poor prognosis, experiencing high rates of mortality, rehospitalization, and socioeconomic burden. MINOCA represents a major unmet need in cardiovascular medicine, with uncertain clinical management. It is a complex condition that can be caused by various factors, including atherosclerosis, plaque rupture, coronary vasospasm, and microvascular dysfunction. Effective management of MINOCA depends on identifying the underlying mechanism of the infarction, thus a systematic diagnostic approach is recommended. Contemporary data shows that a significant number of patients exhibit structural and functional abnormalities in coronary microcirculation, which is referred to as coronary microvascular dysfunction (CMD). CMD plays a crucial role in patients with signs and symptoms of myocardial ischemia and non-obstructive coronary artery stenosis, including MINOCA. Furthermore, conducting a thorough evaluation of coronary function can have significant prognostic and therapeutic implications, since personalized patient management strategies based on this assessment have been shown to improve symptoms and prognosis. Therefore, an accurate and timely diagnosis of CMD is essential for effective patient management, which can be achieved through various invasive and non-invasive methods. This review will discuss the pathophysiological understanding, current diagnostic techniques, and management strategies of patients with MINOCA and CMD.

Sex differences in diagnostic modalities of coronary artery disease: Evidence from coronary microcirculation

Although atherosclerosis is usually considered a disease of the large arteries, risk factors for atherosclerosis also trigger structural and functional abnormalities at a microvascular level. In cardiac disease, microvascular dysfunction is especially relevant in women, among whom the manifestation of ischemic disease due to impaired coronary microcirculation is more common than in men. This sex-specific clinical phenotype has important clinical implications and, given the higher pre-test probability of coronary microvascular dysfunction in females, different diagnostic modalities should be used in women compared to men. In this review, we summarize invasive and non-invasive diagnostic modalities to assess coronary microvascular function, ranging from catheter-based evaluation of endothelial function to Doppler echocardiography and positron emission tomography. Moreover, we discuss different clinical settings in which microvascular disease plays an important role, underlining the importance of choosing the right diagnostic modality depending on the sex of the patients.

Evaluation of left ventricular diastolic function in patients with coronary microvascular dysfunction via cardiovascular magnetic resonance feature tracking

Background

Coronary microvascular dysfunction (CMD) has been suggested to be one of the pathologic mechanisms contributing to heart failure with preserved left ventricular ejection fraction (LVEF) and left ventricular (LV) diastolic dysfunction. We therefore aimed to evaluate LV diastolic function in patients with CMD using cardiovascular magnetic resonance feature tracking (CMR-FT).

Methods

We prospectively enrolled 115 patients referred to cardiology clinics for chest pain assessment who subsequently underwent coronary computed tomography angiogram and stress perfusion CMR. CMD was defined as the presence of subendocardial inducible ischemia detected through visual assessment. LV diastolic function was evaluated using CMR-derived volume-time curves and CMR-FT parameters. The former included early peak filling rate (PFR) and time to PFR; the latter included LV global/regional peak longitudinal diastolic strain rate (LDSR), circumferential diastolic strain rate (CDSR), and radial diastolic strain rate (RDSR).

Results

A total of 92 patients with 1,312 segments were eventually included. Of these, 19 patients were classified as non-CMD (48.8±11.2 years; 63.2% male) and 73 as with CMD (52.3±11.9 years; 54.8% male). The LVEFs were similar and preserved in both groups (P=0.266). At the per-patient level, no differences were observed in PFR, time to PFR, or LV global diastolic strain rates between the two groups. At the per-segment level, 51% (665/1,312) of the myocardial segments were classified as CMD, whereas 49% (647/1,312) were classified as non-CMD. CMD segments showed significantly lower regional CDSR (P=0.019) and RDSR (P=0.006) compared with non-CMD segments.

Conclusions

Despite normal LV ejection fraction in CMD patients, decreased LV diastolic function in CMD myocardial segments indicates early diastolic impairment.

Invasive Coronary Assessment in Myocardial Ischemia with No Obstructive Coronary Arteries

PURPOSE OF REVIEW

The purpose of this review is threefold: (i) to give an overview of well-established invasive methods for assessing patients with ischemia with no obstructive coronary arteries (INOCA) in the cardiac catheterization laboratory; (ii) to describe the prognostic and treatment implications based on these findings, and (iii) to discuss current knowledge gaps and future perspectives.

RECENT FINDINGS

Recent studies have demonstrated that invasive coronary function testing not only allows for risk stratification of patients with INOCA but also guides medical therapy with improvement in symptoms and quality of life. Based on these findings, invasive coronary function assessment is now a class 2a recommendation in the 2021 ACC/AHA chest pain guideline to improve the diagnosis of coronary microvascular dysfunction and to enhance risk stratification. Invasive functional testing for patients with INOCA is well established and easily performed in the catheterization laboratory. Comprehensive invasive assessment is a key to differentiating INOCA endotypes and optimizing both medical therapy and preventive strategies including lifestyle modification.

Evaluation of Ischemia with No Obstructive Coronary Arteries (INOCA) and Contemporary Applications of Cardiac Magnetic Resonance (CMR)

Ischemia with no obstructive coronary arteries (INOCA) is a relatively newly discovered ischemic phenotype that affects patients similarly to obstructive coronary artery disease (CAD) but has a unique pathophysiology and epidemiology. Patients with INOCA present with ischemic signs and symptoms but no obstructive CAD seen on coronary CTA or invasive coronary angiography, which can assess epicardial vessels. The mechanisms of INOCA can be grouped into three endotypes: coronary microvascular dysfunction, epicardial coronary vasospasm, or a combination of both. Accurate and comprehensive assessment of both epicardial and microvascular disease in suspected cases of INOCA is crucial for providing targeted therapy and improving outcomes in this underrepresented population. This review aims to clarify the complex pathophysiology of INOCA, present an overview of invasive and non-invasive diagnostic methods, and examine contemporary approaches for coronary perfusion assessment using cardiac magnetic resonance (CMR). We also explore how recent advancements in quantitative CMR can potentially revolutionize the evaluation of suspected INOCA by offering a rapid, accurate, and non-invasive diagnostic approach, thereby reducing the alarming number of cases that go undetected.

Reduced left ventricular function on cardiac MRI of SLE patients correlates with measures of disease activity and inflammation

Background

Women with SLE have an elevated risk of cardiovascular disease. Many women with SLE frequently report chest pain in the absence of obstructive coronary artery disease (CAD) due to coronary microvascular dysfunction (CMD), a form of ischemia with no obstructive CAD. Echocardiographic studies have shown that SLE patients have reduced left ventricular (LV) function, which may also correlate with higher SLE disease activity scores. As such, we used cardiac magnetic resonance imaging (cMRI) to investigate the relationship between SLE, related inflammatory biomarkers, and cardiac function in female SLE patients.

Methods

We performed stress cMRI in women with SLE and chest pain with no obstructive CAD (n=13, all met ACR 1997 criteria,) and reference controls (n=22) using our published protocol. We evaluated LV function, tissue characterization (T1 mapping, ECV), and delayed enhancement, using CV142 software (Circle Cardiovascular Imaging Inc, Calgary, AB, Canada). Myocardial perfusion reserve index (MPRI) was calculated using our published protocol. SLEDAI and SLICC Damage Index (DI) were calculated per validated criteria. Serum samples were analyzed for inflammatory markers and autoantibodies. Wilcoxon rank-sum test was performed on clinical values with CMD and no CMD SLE subjects, and on cMRI values with all SLE subjects and controls. Correlation analysis was done on clinical values, and cMRI values on all SLE subjects.

Results

Overall, 40% of SLE subjects had MPRI values < 1.84, consistent with CMD. Compared to controls, SLE subjects had significantly lower LVEF, and higher LVESVi and LVMi. Corresponding to this, radial, longitudinal, and circumferential strain were significantly lower in the SLE subjects. In correlation analysis of serum inflammatory biomarkers to cMRI values in the SLE subjects, SLICC DI was related to worse cardiac function (lower radial, circumferential and longitudinal strain) and higher T1 time. Additionally, fasting insulin and ESR were negatively correlated with LVMi. Fasting insulin also negatively correlated with ECV. CRP had a positive association with LVESV index and CI and a negative association with longitudinal strain.

Conclusions

Among women with SLE with chest pain and no obstructive CAD, 40% have CMD. While evaluations of known inflammatory markers (such as CRP and ESR) predictably correlated with decreased cardiac function, our study found that decreased fasting insulin levels as a novel marker of diminished LV function. In addition, low insulin levels were observed to correlate with increased LVMi and ECV, suggesting a cardioprotective effect of insulin in SLE patients. We also noted that SLICC DI, an assessment of SLE damage, correlates with cardiac dysfunction in SLE. Our findings underline the potential of non-invasive cMRI as a tool for monitoring cardiovascular function in SLE, particularly in patients with high SLICC DI, ESR and CRP and low fasting insulin levels.

Coronary Microvascular Dysfunction: What Clinicians and Investigators Should Know

PURPOSE OF REVIEW

Abnormal structure and function of the coronary microvasculature have been implicated in the pathophysiology of multiple cardiovascular disease processes. This article reviews recent research progress related to coronary microvascular dysfunction (CMD) and salient clinical takeaways.

RECENT FINDINGS

CMD is prevalent in patients with signs and symptoms of ischemia and no obstructive epicardial coronary artery disease (INOCA), particularly in women. CMD is associated with adverse outcomes, including most frequently the development of heart failure with preserved ejection fraction. It is also associated with adverse outcomes in patient populations including hypertrophic cardiomyopathy, dilated cardiomyopathy, and acute coronary syndromes. In patients with INOCA, stratified medical therapy guided by invasive coronary function testing to define the subtype of CMD leads to improved symptoms. There are invasive and non-invasive methodologies to diagnose CMD that provide prognostic information and mechanistic information to direct treatment. Available treatments improve symptoms and myocardial blood flow; ongoing investigations aim to develop therapy to improve adverse outcomes related to CMD.

Imaging Early Life Cardiovascular Phenotype

The growing epidemics of obesity, hypertension, and diabetes, in addition to worsening environmental factors such as air pollution, water scarcity, and climate change, have fueled the continuously increasing prevalence of cardiovascular diseases (CVDs). This has caused a markedly increasing burden of CVDs that includes mortality and morbidity worldwide. Identification of subclinical CVD before overt symptoms can lead to earlier deployment of preventative pharmacological and nonpharmacologic strategies. In this regard, noninvasive imaging techniques play a significant role in identifying early CVD phenotypes. An armamentarium of imaging techniques including vascular ultrasound, echocardiography, magnetic resonance imaging, computed tomography, noninvasive computed tomography angiography, positron emission tomography, and nuclear imaging, with intrinsic strengths and limitations can be utilized to delineate incipient CVD for both clinical and research purposes. In this article, we review the various imaging modalities used for the evaluation, characterization, and quantification of early subclinical cardiovascular diseases.

MINOCA and INOCA: Role in Heart Failure

PURPOSE OF REVIEW

Infarction (MINOCA) and ischaemia (INOCA) with non-obstructive coronary disease are recent non-conventional presentations of coronary syndromes that are increasingly recognised in the clinical arena, particularly with the availability of new cardiovascular imaging techniques. Both are related to heart failure (HF). MINOCA is not associated with benign outcomes, and HF is among the most prevalent events. Regarding INOCA, microvascular dysfunction has also been found to associate with HF, particularly with preserved ejection fraction (HFpEF).

RECENT FINDINGS

Regardless of the several aetiologies underlying HF in MINOCA, it is likely related to LV dysfunction, where secondary prevention is not yet clearly established. Regarding INOCA, coronary microvascular ischaemia has been associated to endothelial dysfunction leading ultimately to diastolic dysfunction and HFpEF. MINOCA and INOCA are clearly related to HF. In both, there is a lack of studies on the identification of the risk factors for HF, diagnostic workup and, importantly, the appropriate primary and secondary prevention strategies.

Contemporary Diagnosis and Management of Patients with MINOCA

PURPOSE OF REVIEW

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is defined as acute myocardial infarction (MI) with angiographically no obstructive coronary artery disease or stenosis ≤ 50%. MINOCA is diagnostically challenging and complex, making it difficult to manage effectively. This condition accounts for 6-8% of all MI and poses an increased risk of morbidity and mortality after diagnosis. Prompt recognition and targeted management are essential to improve outcomes and our understanding of this condition, but this process is not yet standardized. This article offers a comprehensive review of MINOCA, delving deep into its unique clinical profile, invasive and noninvasive diagnostic strategies for evaluating MINOCA in light of the lack of widespread availability for comprehensive testing, and current evidence surrounding targeted therapies for patients with MINOCA.

RECENT FINDINGS

MINOCA is not uncommon and requires comprehensive assessment using various imaging modalities to evaluate it further. MINOCA is a heterogenous working diagnosis that requires thoughtful approach to diagnose the underlying disease responsible for MINOCA further.

Autoimmune rheumatic diseases in women with coronary microvascular dysfunction: a report from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) project

Background

While autoimmune rheumatic diseases (ARDs) have been linked with coronary microvascular dysfunction (CMD), the relationship between ARD and CMD in women with signs and symptoms of ischemia and no obstructive arteries (INOCA) are not well described. We hypothesized that among women with CMD, those with ARD history have greater angina, functional limitations, and myocardial perfusion compromise compared to those without ARD history.

Methods

Women with INOCA and confirmed CMD by invasive coronary function testing were included from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) project (NCT00832702). Seattle Angina Questionnaire (SAQ), Duke Activity Status Index (DASI), and cardiac magnetic resonance myocardial perfusion reserve index (MPRI) were collected at baseline. Chart review was performed to confirm self-reported ARD diagnosis.

Results

Of the 207 women with CMD, 19 (9%) had a confirmed history of ARD. Compared to those without ARD, women with ARD were younger (p = 0.04). In addition, they had lower DASI-estimated metabolic equivalents (p = 0.03) and lower MPRI (p = 0.008) but similar SAQ scores. There was a trend towards increased nocturnal angina and stress-induced angina in those with ARD (p = 0.05 for both). Invasive coronary function variables were not significantly different between groups.

Conclusions

Among women with CMD, women with a history of ARD had lower functional status and worse myocardial perfusion reserve compared to women without ARD. Angina-related health status and invasive coronary function were not significantly different between groups. Further studies are warranted to understand mechanisms contributing to CMD among women with ARDs with INOCA.

Myocardial Infarction with Non-Obstructive Coronary Arteries (MINOCA): Focus on Coronary Microvascular Dysfunction and Genetic Susceptibility

Among the most common causes of death worldwide, ischemic heart disease (IHD) is recognized to rank first. Even if atherosclerotic disease of the epicardial arteries is known as the leading cause of IHD, the presence of myocardial infarction with non-obstructive coronary artery disease (MINOCA) is increasingly recognized. Notwithstanding the increasing interest, MINOCA remains a puzzling clinical entity that can be classified by distinguishing different underlying mechanisms, which can be divided into atherosclerotic and non-atherosclerotic. In particular, coronary microvascular dysfunction (CMD), classifiable in non-atherosclerotic mechanisms, is a leading factor for the pathophysiology and prognosis of patients with MINOCA. Genetic susceptibility may have a role in primum movens in CMD. However, few results have been obtained for understanding the genetic mechanisms underlying CMD. Future studies are essential in order to find a deeper understanding of the role of multiple genetic variants in the genesis of microcirculation dysfunction. Progress in research would allow early identification of high-risk patients and the development of pharmacological, patient-tailored strategies. The aim of this review is to revise the pathophysiology and underlying mechanisms of MINOCA, focusing on CMD and actual knowledge about genetic predisposition to it.

Prognostic value of combined coronary angiography-derived IMR and myocardial perfusion imaging by CZT SPECT in INOCA

BACKGROUND

A significant proportion of ischemia with non-obstructive coronary artery disease (INOCA) demonstrate coronary microvascular dysfunction (CMD), a condition associated with abnormal myocardial perfusion imaging (MPI) and adverse outcomes. Coronary angiography-derived index of microvascular resistance (caIMR) is a novel non-invasive technique to assess CMD. We aimed to investigate the prognostic value of combined caIMR and MPI by CZT SPECT in INOCA patients.

METHODS

Consecutive 151 patients with chest pain and < 50% coronary stenosis who underwent coronary angiography and MPI within 3 months were enrolled. caIMR was calculated by computational pressure-flow dynamics. CMD was defined as caIMR ≥ 25. The endpoint was major adverse cardiac events (MACE: cardiovascular death, nonfatal myocardial infarction, revascularization, angina-related rehospitalization, heart failure, and stroke).

RESULTS

Of all INOCA patients, CMD was present in 93 (61.6%) patients. The prevalence of abnormal MPI was significantly higher in CMD compared with non-CMD patients (40.9% vs 13.8%, P < .001). CMD showed a higher risk of MACE than non-CMD patients. Patients with both CMD and abnormal MPI had the worst prognosis, followed by patients with CMD and normal MPI (log-rank P < .001). Cox regression analysis identified CMD (HR 3.121, 95%CI 1.221-7.974, P = .017) and MPI (HR 2.704, 95%CI 1.030-7.099, P = .043) as predictive of MACE. The prognostic value of INOCA patients enhanced significantly by adding CMD and MPI to the model with clinical risk factors (AUC = 0.777 vs 0.686, P = .030).

CONCLUSION

caIMR-derived CMD is associated with increased risk of MACE among INOCA patients. Patients with abnormalities on both caIMR and MPI had the worse outcomes.

Strengths and weaknesses of alternative noninvasive imaging approaches for microvascular ischemia

Structural and functional abnormalities of coronary microvasculature are highly prevalent in several clinical settings and often associated with worse clinical outcomes. Therefore, there is a growing interest in the detection and treatment of this, often overlooked, disease. Coronary angiography allows the assessment of the Coronary flow reserve (CFR) and the index of microcirculatory resistance (IMR). However, the measurement of these parameters is not always feasible because of limited technical availability and the need for a cardiac catheterization with a small but real risk of potential complications. Recent advances in non-invasive imaging techniques allow the assessment of coronary microvascular function with good accuracy and reproducibility. The objective of this review is to discuss the strengths and weaknesses of alternative non-invasive approaches used in the diagnosis of coronary microvascular dysfunction (CMD), highlighting the most recent advances for each imaging modality.

Qualitative and Quantitative Stress Perfusion Cardiac Magnetic Resonance in Clinical Practice: A Comprehensive Review

Stress cardiovascular magnetic resonance (CMR) imaging is a well-validated non-invasive stress test to diagnose significant coronary artery disease (CAD), with higher diagnostic accuracy than other common functional imaging modalities. One-stop assessment of myocardial ischemia, cardiac function, and myocardial viability qualitatively and quantitatively has been proven to be a cost-effective method in clinical practice for CAD evaluation. Beyond diagnosis, stress CMR also provides prognostic information and guides coronary revascularisation. In addition to CAD, there is a large body of literature demonstrating CMR's diagnostic performance and prognostic value in other common cardiovascular diseases (CVDs), especially coronary microvascular dysfunction (CMD). This review focuses on the clinical applications of stress CMR, including stress CMR scanning methods, practical interpretation of stress CMR images, and clinical utility of stress CMR in a setting of CVDs with possible myocardial ischemia.

Sex-Specific Stress Perfusion Cardiac Magnetic Resonance Imaging in Suspected Ischemic Heart Disease: Insights From SPINS Retrospective Registry

BACKGROUND

Cardiovascular disease (CVD) remains the leading cause of mortality in women, but current noninvasive cardiac imaging techniques have sex-specific limitations.

OBJECTIVES

In this study, the authors sought to investigate the effect of sex on the prognostic utility and downstream invasive revascularization and costs of stress perfusion cardiac magnetic resonance (CMR) for suspected CVD.

METHODS

Sex-specific prognostic performance was evaluated in a 2,349-patient multicenter SPINS (Stress CMR Perfusion Imaging in the United States [SPINS] Study) registry. The primary outcome measure was a composite of cardiovascular death and nonfatal myocardial infarction; secondary outcomes were hospitalization for unstable angina or heart failure, and late unplanned coronary artery bypass grafting.

RESULTS

SPINS included 1,104 women (47% of cohort); women had higher prevalence of chest pain (62% vs 50%; P < 0.0001) but lower use of medical therapies. At the 5.4-year median follow-up, women with normal stress CMR had a low annualized rate of primary composite outcome similar to men (0.54%/y vs 0.75%/y, respectively; P = NS). In contrast, women with abnormal CMR were at higher risk for both primary (3.74%/y vs 0.54%/y; P < 0.0001) and secondary (9.8%/y vs 1.6%/y; P < 0.0001) outcomes compared with women with normal CMR. Abnormal stress CMR was an independent predictor for the primary (HR: 2.64 [95% CI: 1.20-5.90]; P = 0.02) and secondary (HR: 2.09 [95% CI: 1.43-3.08]; P < 0.0001) outcome measures. There was no effect modification for sex. Women had lower rates of invasive coronary angiography (ICA; 3.6% vs 7.3%; P = 0.0001) and downstream costs ($114 vs $171; P = 0.001) at 90 days following CMR. There was no effect of sex on diagnostic image quality.

CONCLUSIONS

Stress CMR demonstrated excellent prognostic performance with lower rates of ICA referral in women. Stress CMR should be considered as a first-line noninvasive imaging tool for the evaluation of women. (Stress CMR Perfusion Imaging in the United States [SPINS] Study [SPINS]; NCT03192891).

Sex differences in contributors to coronary microvascular dysfunction

Background

Coronary microvascular dysfunction (CMD) has differences in prevalence and presentation between women and men; however, we have limited understanding about underlying contributors to sex differences in CMD. Myocardial perfusion reserve index (MPRI), as semi-quantitative measure of myocardial perfusion derived from cardiac magnetic resonance (CMR) imaging has been validated as a measure of CMD. We sought to understand the sex differences in the relations between the MPRI and traditional measures of cardiovascular disease by CMR.

Methods

A retrospective analysis of a single-center cohort of patients receiving clinical stress CMR from 2015 to 2022 was performed. Patients with calculated MPRI and no visible perfusion defects consistent with obstructive epicardial coronary disease were included. We compared associations between MPRI versus traditional cardiovascular risk factors and markers of cardiac structure/function in sex-stratified populations using univariable and multivariable regression models.

Results

A total of 229 patients [193 female, 36 male, median age 57 (47-67) years] were included in the analysis. In the female population, no traditional cardiovascular risk factors were associated with MPRI, whereas in the male population, diabetes (β: -0.80, p = 0.03) and hyperlipidemia (β: -0.76, p = 0.006) were both associated with reduced MPRI in multivariable models. Multivariable models revealed significant associations between reduced MPRI and increased ascending aortic diameter (β: -0.42, p = 0.005) and T1 times (β: -0.0056, p = 0.03) in the male population, and increased T1 times (β: -0.0037, p = 0.006) and LVMI (β: -0.022, p = 0.0003) in the female population.

Conclusion

The findings suggest different underlying pathophysiology of CMD in men versus women, with lower MPRI in male patients fitting a more "traditional" atherosclerotic profile.

2023 Guidelines of the Taiwan Society of Cardiology on the Diagnosis and Management of Chronic Coronary Syndrome

Coronary artery disease (CAD) covers a wide spectrum from persons who are asymptomatic to those presenting with acute coronary syndromes (ACS) and sudden cardiac death. Coronary atherosclerotic disease is a chronic, progressive process that leads to atherosclerotic plaque development and progression within the epicardial coronary arteries. Being a dynamic process, CAD generally presents with a prolonged stable phase, which may then suddenly become unstable and lead to an acute coronary event. Thus, the concept of "stable CAD" may be misleading, as the risk for acute events continues to exist, despite the use of pharmacological therapies and revascularization. Many advances in coronary care have been made, and guidelines from other international societies have been updated. The 2023 guidelines of the Taiwan Society of Cardiology for CAD introduce a new concept that categorizes the disease entity according to its clinical presentation into acute or chronic coronary syndromes (ACS and CCS, respectively). Previously defined as stable CAD, CCS include a heterogeneous population with or without chest pain, with or without prior ACS, and with or without previous coronary revascularization procedures. As cardiologists, we now face the complexity of CAD, which involves not only the epicardial but also the microcirculatory domains of the coronary circulation and the myocardium. New findings about the development and progression of coronary atherosclerosis have changed the clinical landscape. After a nearly 50-year ischemia-centric paradigm of coronary stenosis, growing evidence indicates that coronary atherosclerosis and its features are both diagnostic and therapeutic targets beyond obstructive CAD. Taken together, these factors have shifted the clinicians' focus from the functional evaluation of coronary ischemia to the anatomic burden of disease. Research over the past decades has strengthened the case for prevention and optimal medical therapy as central interventions in patients with CCS. Even though functional capacity has clear prognostic implications, it does not include the evaluation of non-obstructive lesions, plaque burden or additional risk-modifying factors beyond epicardial coronary stenosis-driven ischemia. The recommended first-line diagnostic tests for CCS now include coronary computed tomographic angiography, an increasingly used anatomic imaging modality capable of detecting not only obstructive but also non-obstructive coronary plaques that may be missed with stress testing. This non-invasive anatomical modality improves risk assessment and potentially allows for the appropriate allocation of preventive therapies. Initial invasive strategies cannot improve mortality or the risk of myocardial infarction. Emphasis should be placed on optimizing the control of risk factors through preventive measures, and invasive strategies should be reserved for highly selected patients with refractory symptoms, high ischemic burden, high-risk anatomies, and hemodynamically significant lesions. These guidelines provide current evidence-based diagnosis and treatment recommendations. However, the guidelines are not mandatory, and members of the Task Force fully realize that the treatment of CCS should be individualized to address each patient's circumstances. Ultimately, the decision of healthcare professionals is most important in clinical practice.

The Importance of Integrated Regulation Mechanism of Coronary Microvascular Function for Maintaining the Stability of Coronary Microcirculation: An Easily Overlooked Perspective

Coronary microvascular dysfunction (CMD) refers to a group of disorders affecting the structure and function of coronary microcirculation and is associated with an increased risk of major adverse cardiovascular events. At present, great progress has been made in the diagnosis of CMD, but there is no specific treatment for it because of the complexity of CMD pathogenesis. Vascular dysfunction is one of the important causes of CMD, but previous reviews mostly considered microvascular dysfunction as a whole abnormality so the obtained conclusions are skewed. The coronary microvascular function is co-regulated by multiple mechanisms, and the mechanisms by which microvessels of different luminal diameters are regulated vary. The main purpose of this review is to revisit the mechanisms by which coronary microvessels at different diameters regulate coronary microcirculation through integrated sequential activation and briefly discuss the pathogenesis, diagnosis, and treatment progress of CMD from this perspective.

Phenotype-based management of coronary microvascular dysfunction

40-70% of patients undergoing invasive coronary angiography with signs and symptoms of ischemia are found to have no obstructive coronary artery disease (INOCA). When this heterogeneous group undergo coronary function testing, approximately two-thirds have demonstrable coronary microvascular dysfunction (CMD), which is independently associated with adverse prognosis. There are four distinct phenotypes, or subgroups, each with unique pathophysiological mechanisms and responses to therapies. The clinical phenotypes are microvascular angina, vasospastic angina, mixed (microvascular and vasospastic), and non-cardiac symptoms (reclassification as non-INOCA). The Coronary Vasomotor Disorders International Study Group (COVADIS) have proposed standardized criteria for diagnosis. There is growing awareness of these conditions among clinicians and within guidelines. Testing for CMD can be done using invasive or non-invasive modalities. The CorMicA study advocates the concept of 'functional angiography' to guide stratified medical therapy. Therapies broadly fall into two categories: those that modulate cardiovascular risk and those to alleviate angina. Management should be tailored to the individual, with periodic reassessment for efficacy. Phenotype-based management is a worthy endeavor for both patients and clinicians, aligning with the concept of 'precision medicine' to improve prognosis, symptom burden, and quality of life. Here, we present a contemporary approach to the phenotype-based management of patients with INOCA.

Impairment in quantitative microvascular function in non-ischemic cardiomyopathy as demonstrated using cardiovascular magnetic resonance

Background

Microvascular dysfunction (MVD) is present in various cardiovascular diseases and portends worse outcomes. We assessed the prevalence of MVD in patients with non-ischemic cardiomyopathy (NICM) as compared to subjects with preserved ejection fraction (EF) using stress cardiovascular magnetic resonance (CMR).

Methods

We retrospectively studied consecutive patients with NICM and 58 subjects with preserved left ventricular (LV) EF who underwent stress CMR between 2011–2016. MVD was defined visually as presence of a subendocardial perfusion defect and semiquantitatively by myocardial perfusion reserve index (MPRI<1.51). MPRI was compared between groups using univariate analysis and multivariable linear regression.

Results

In total, 41 patients with NICM (mean age 51 ± 14, 59% male) and 58 subjects with preserved LVEF (mean age 51 ± 13, 31% male) were identified. In the NICM group, MVD was present in 23 (56%) and 11 (27%) by semiquantitative and visual evaluation respectively. Compared to those with preserved LVEF, NICM patients had lower rest slope (3.9 vs 4.9, p = 0.05) and stress perfusion slope (8.8 vs 11.7, p<0.001), and MPRI (1.41 vs 1.74, p = 0.02). MPRI remained associated with NICM after controlling for age, gender, hypertension, ethnicity, diabetes, and late gadolinium enhancement (log MPR, β coefficient = -0.19, p = 0.007).

Conclusions

MVD—as assessed using CMR—is highly prevalent in NICM as compared to subjects with preserved LVEF even after controlling for covariates. Semiquantitative is able to detect a greater number of incidences of MVD compared to visual methods alone. Further studies are needed to determine whether treatment of MVD is beneficial in NICM.

The risk of acute coronary events in microvascular disease

The microvascular disease represents a widespread clinical entity in the general population, especially among women. The dysfunction of the microcirculation is often responsible for myocardial ischaemia and angina in the absence of significant stenosis of the epicardial district, while in other cases it can represent a contributing cause of angina even in the presence of coronary artery disease, cardiomyopathies or heart failure. The cardiovascular risk factors of people with microvascular disease are similar to those who develop epicardial atherosclerotic disease. However, the prognostic significance of microvascular disease remains a matter of debate. An element to be clarified, in fact, is whether subjects with dysfunction of the microcirculation and coronary tree without significant stenoses present an increased risk of myocardial infarction and sudden death. In recent years, several studies seem to confirm an association between microvascular disease and progression of coronary epicardial atherosclerosis. The prognosis of microvascular disease would therefore not be benign as was previously believed, but associated with an increased risk of cardiovascular events including revascularization, heart attack, and cardiac death.

Global trends and frontiers in research on coronary microvascular dysfunction: a bibliometric analysis from 2002 to 2022

BACKGROUND

Coronary microvascular dysfunction (CMD) is a leading cause of ischemic heart disease. Over the past few decades, considerable progress has been made with respect to research on CMD. The present study summarized the current research hotspots and trends on CMD by applying a bibliometric approach.

METHODS

Relevant publications between 2002 and 2022 were extracted from the Web of Science Core Collection. Visualization network maps of countries, institutions, authors, and co-cited authors were built using VOSviewer. CiteSpace was used for keyword analysis and the construction of a dual-map overlay of journals and a timeline view of co-cited references.

RESULTS

1539 CMD-related publications were extracted for bibliometric analysis. The annual publications generally showed an upward trend. The United States of America was the most prolific country, with 515 publications (33.5%). Camici P. G. was the most influential author, whereas the European Heart Journal, Circulation, and Journal of the American College of Cardiology were the most authoritative journals. Research hotspot analysis revealed that endothelial dysfunction as well as reduced nitric oxide production or bioavailability played critical roles in CMD development. Positron emission tomography was the most widely used imaging method for diagnosis. In addition, microvascular angina, hypertrophic cardiomyopathy, and heart failure have attracted much attention as the main clinical implications. Furthermore, international standards for CMD diagnosis and management may be the future research directions.

CONCLUSIONS

This study offers a comprehensive view about the hotspots and development trends of CMD, which can assist subsequent researchers and guide future directions.

Multimodality Imaging in the Detection of Ischemic Heart Disease in Women

Women with coronary artery disease tend to have a worse short and long-term prognosis relative to men and the incidence of atherosclerotic cardiovascular disease is increasing. Women are less likely to present with classic anginal symptoms when compared with men and more likely to be misdiagnosed. Several non-invasive imaging modalities are available for diagnosing ischemic heart disease in women and many of these modalities can also assist with prognostication and help to guide management. Selection of the optimal imaging modality to evaluate women with possible ischemic heart disease is a scenario which clinicians often encounter. Earlier modalities such as exercise treadmill testing demonstrate significant performance variation in men and women, while newer modalities such as coronary CT angiography, myocardial perfusion imaging and cardiac magnetic resonance imaging are highly specific and sensitive for the detection of ischemia and coronary artery disease with greater parity between sexes. Individual factors, availability, diagnostic performance, and female-specific considerations such as pregnancy status may influence the decision to select one modality over another. Emerging techniques such as strain rate imaging, CT-myocardial perfusion imaging and cardiac magnetic resonance imaging present additional options for diagnosing ischemia and coronary microvascular dysfunction.

Clinical Practice Variations in the Management of Ischemia With No Obstructive Coronary Artery Disease

Background Ischemia with no obstructive coronary artery disease is a condition associated with major adverse cardiovascular outcomes. To date, there are no specific American Heart Association or American College of Cardiology guidelines. The objective of this survey is to better understand the clinical practice and knowledge gaps that exist nationally. Methods and Results Participant-specific links for a survey with 11 questions and 3 reminders were sent between September and October 2020 to the American College of Cardiology CardioSurve Panel. The panel consist of randomly selected cardiologists (n=437) who represent the current profile of the American College of Cardiology US membership. The survey received a 30% response rate. Of the 172 respondents, 130 (76%) indicated that they have treated patients with ischemia with no obstructive coronary artery disease. Although the majority (69%) are generally confident in their ability to manage this condition, 1 of 3 report lack of confidence or are neutral. The American College of Cardiology/American Heart Association Chronic Stable Angina Guidelines are the most commonly used reference for treating ischemia with no obstructive coronary artery disease (81%), with most cardiologists wanting additional clinical guidance, such as randomized controlled trials (61%). More than 4 of 5 cardiologists rarely or never order advanced imaging modalities to assess coronary flow reserve. Approximately 2 of 3 of respondents frequently prescribe statins (68%), aspirin (66%), calcium channel blockers (63%), and β blockers or α/β blockers (55%). However, nearly 70% never prescribe angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. Conclusions This survey demonstrates heterogeneity in the management of ischemia with no obstructive coronary artery disease among US cardiologists, identifies support for guideline development, and outlines knowledge gaps for research and education in the therapeutic management of this condition.

A clinical trial for computed tomography myocardial perfusion based non-invasive index of microcirculatory resistance (MPBIMR): rationale and trial design

INTRODUCTION

Accurate and rapid assessment of the coronary microcirculation has become an important medical challenge. However, reliable and non-invasive quantitative methods to diagnose coronary microvascular disease (CMVD), select treatments for coronary artery disease (CAD), and therefore improve coronary microcirculation are lacking. Current detection methods have limitations. Therefore, we will assess whether a new detection method, the non-invasive index of microcirculatory resistance (IMR), based on computed tomography (CT) perfusion and hydrodynamics (CT-IMR), can effectively evaluate the function of coronary microvessels.

METHODS

We will conduct a multicenter, randomized, open-label study, including a Phase I single-center and Phase II multicenter trial, to assess the accuracy of the non-invasive CT-IMR coronary measurement of microcirculation function. The study will enroll 295 patients who will undergo coronary CT angiography (CCTA), dynamic CT-myocardial perfusion imaging (CT-MPI), invasive coronary angiography (ICA), and invasive IMR. This study will identify the key influencing factors when calculating myocardial microcirculation perfusion and develop an accurate three-dimensional coronary reconstruction method and a non-invasive coronary IMR calculation method based on computational fluid dynamics (CFD). This will facilitate the development of a non-invasive system to detect and measure coronary microcirculation.

CONCLUSION

The clinical trial for computed tomography myocardial perfusion based non-invasive index of microcirculatory resistance (MPBIMR) will establish the key influencing factors when calculating myocardial microcirculation perfusion and create a non-invasive CT-IMR calculation method based on CFD. This method may diagnose patients with simple coronary microvascular lesions and those with coronary microvascular lesions combined with coronary vascular lesions.