Invasive coronary physiology in patients with angina and non-obstructive coronary artery disease: a consensus document from the coronary microvascular dysfunction workstream of the British Heart Foundation/National Institute for Health Research Partnership

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

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

Advances in the diagnosis and management of post-percutaneous coronary intervention coronary microvascular dysfunction: Insights into pathophysiology and metabolic risk interactions

Percutaneous coronary intervention (PCI), as an essential treatment for coronary artery disease, has significantly improved the prognosis of patients with large coronary artery lesions. However, some patients continue to experience myocardial ischemic symptoms post-procedure, largely due to coronary microvascular dysfunction (CMD). The pathophysiological mechanisms of CMD are complex and involve endothelial dysfunction, microvascular remodeling, reperfusion injury, and metabolic abnormalities. Moreover, components of metabolic syndrome, including obesity, hyperglycemia, hypertension, and dyslipidemia, exacerbate the occurrence and progression of CMD through multiple pathways. This review systematically summarizes the latest research advancements in CMD after PCI, including its pathogenesis, diagnostic techniques, management strategies, and future research directions. For diagnosis, invasive techniques such as coronary flow reserve and the index of microcirculatory resistance, as well as non-invasive imaging modalities (positron emission tomography and cardiac magnetic resonance), provide tools for early CMD detection. In terms of management, a multi-level intervention strategy is emphasized, incorporating lifestyle modifications (diet, exercise, and weight control), pharmacotherapy (vasodilators, hypoglycemic agents, statins, and metabolic modulators), traditional Chinese medicine, and specialized treatments (enhanced external counterpulsation, metabolic surgery, and lipoprotein apheresis). However, challenges remain in CMD treatment, including limitations in diagnostic tools and the lack of personalized treatment strategies. Future research should focus on the complex interactions between CMD and metabolic risks, aiming to optimize diagnostic and therapeutic strategies to improve the long-term prognosis of patients post-PCI.

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.

Exploring the interplay between coronary microvascular dysfunction and mental health

BACKGROUND

The intricate relationship between mental health disorders, notably anxiety and depression, and chest pain associated with non-obstructive coronary artery disease has become a focus of investigation.

METHODS

This study from the Coronary Microvascular Disease Registry (CMDR) evaluated the association of mental health disorders and coronary microvascular dysfunction (CMD) among patients with angina with no obstructive coronary artery disease (ANOCA) who had undergone comprehensive invasive physiological testing for CMD. Clinical data regarding baseline characteristics, comorbidities, and noninvasive cardiac testing were obtained from chart review. The primary outcome of interest was the potential relationship between mental health diagnoses and the presence of CMD.

RESULTS

Of patients included in the CMDR, 27 % (41/152) had at least one documented mental health disorder diagnosis (International Classification of Diseases, Tenth Revision codes) and CMD. There was no difference in mental health diagnosis prevalence between CMD-positive and CMD-negative patients (21.1 % vs. 28.9 %, p = 0.34). The most common mental health diagnoses were depression (15.8 %) and anxiety (15.8 %). Furthermore, 46.3 % (19/41) of patients with mental health disorders were prescribed psychiatric medications, with the most common being benzodiazepines (26.8 %).

CONCLUSION

Patients with chest pain not due to CMD did not have an increased prevalence of mental health disorders compared with patients with ANOCA due to CMD, challenging the notion of a psychosomatic component in the pathogenesis of ANOCA.

Coronary microvascular dysfunction and inflammation: Insights from the Coronary Microvascular Disease Registry

BACKGROUND

Coronary microvascular dysfunction (CMD) is associated with various inflammatory conditions that worsen endothelial dysfunction. This study aimed to investigate the relationship between CMD and inflammation using common inflammatory markers derived from complete blood count (CBC) analysis.

METHODS

Information was gathered from the Coronary Microvascular Disease Registry to examine the neutrophil-to-lymphocyte ratio (NLR), eosinophil-to-monocyte ratio (EMR), and monocyte-to-high-density lipoprotein ratio (MHR) in a cohort of patients with angina who showed non-obstructive coronary arteries and underwent invasive physiological assessments for CMD.

RESULTS

Of the 171 patients studied, 126 were CMD-negative and 45 were CMD-positive, constituting two groups of interest. The average age of all patients was 61.7 ± 11.1 years, and 63.7 % were female. No significant differences were observed between the two groups in terms of baseline characteristics, cardiovascular risk factors, or potential anti-inflammatory medications. Furthermore, there were no statistically significant differences in NLR (2.54 ± 3.71 vs. 2.52 ± 2.28, p = 0.97), EMR (0.3 ± 0.21 vs. 0.34 ± 0.29, p = 0.31), or MHR (0.02 ± 0.01 vs. 0.01 ± 0.01, p = 0.54) between CMD-positive and CMD-negative patients.

CONCLUSION

Our findings did not show a noteworthy connection between CMD and inflammation, as suggested by various simple CBC-based biomarkers.

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

BACKGROUND

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Novel diagnostic approaches and management of coronary microvascular dysfunction

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

The role of coronary microvascular dysfunction in the pathogenesis of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a common condition with few effective therapies and hence represents a major healthcare burden. The clinical syndrome of HFpEF can be caused by varying pathophysiological processes, with coronary microvascular dysfunction (CMD) proposed as one of the aetiologies, although confirming causality has been challenging. CMD is characterised by the inability of the coronary vasculature to augment blood flow in response to a physiological stressor and has been established as the driver of angina in patients with non-obstructed coronaries (ANOCA), and this has subsequently led to efficacious endotype-directed therapies. CMD is also highly prevalent among sufferers of HFpEF and may represent a novel treatment target for this particular endotype of this condition. This review aims to discuss the role of the microcirculation in the healthy heart how it's dysfunction may precipitate HFpEF and explore the current diagnostic tools available. We also discuss the gaps in evidence and where we believe future research should be focussed.

Coronary microvascular dysfunction, arrythmias, and sudden cardiac death: A literature review

The coronary vascular system has a unique structure and function that is adaptive to myocardial demand. It is composed of a continuous network of vessels receding in size from epicardial arteries to the microvascular circulation. Failure to meet myocardial demand results in ischemia, angina, and adverse myocardial outcomes. It is evident that 50 % of patients with angina have a non-obstructive coronary disease and 66 % of these patients have coronary microvascular dysfunction (CMD). The impact of CMD on the atria and ventricles is exhibited through its association with atrial fibrillation and distortion of ventricular repolarization. Ultimately, this influence increases the risk of mortality, morbidity, and sudden cardiac arrest. CMD serves as an independent risk for atrial fibrillation, increases ventricular electrical inhomogeneity, and contributes to the progression of cardiac disease. The underlying pathogenesis may be attributed to oxidative stress evident through reactive oxygen species, impaired vasoactive function, and structural disorders such as fibrotic changes. Myocardial ischemia, brought about by a demand-supply mismatch in CMD, may create a milieu for ventricular arrythmia and sudden cardiac arrest through distortion of ventricular repolarization parameters such as QT dispersion and corrected QT dispersion.

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.

Rethinking False Positive Exercise Electrocardiographic Stress Tests by Assessing Coronary Microvascular Function

BACKGROUND

Exercise electrocardiographic stress testing (EST) has historically been validated against the demonstration of obstructive coronary artery disease. However, myocardial ischemia can occur because of coronary microvascular dysfunction (CMD) in the absence of obstructive coronary artery disease.

OBJECTIVES

The aim of this study was to assess the specificity of EST to detect an ischemic substrate against the reference standard of coronary endothelium-independent and endothelium-dependent microvascular function in patients with angina with nonobstructive coronary arteries (ANOCA).

METHODS

Patients with ANOCA underwent invasive coronary physiological assessment using adenosine and acetylcholine. CMD was defined as impaired endothelium-independent and/or endothelium-dependent function. EST was performed using a standard Bruce treadmill protocol, with ischemia defined as the appearance of ≥0.1-mV ST-segment depression 80 ms from the J-point on electrocardiography. The study was powered to detect specificity of ≥91%.

RESULTS

A total of 102 patients were enrolled (65% women, mean age 60 ± 8 years). Thirty-two patients developed ischemia (ischemic group) during EST, whereas 70 patients did not (nonischemic group); both groups were phenotypically similar. Ischemia during EST was 100% specific for CMD. Acetylcholine flow reserve was the strongest predictor of ischemia during exercise. Using endothelium-independent and endothelium-dependent microvascular dysfunction as the reference standard, the false positive rate of EST dropped to 0%.

CONCLUSIONS

In patients with ANOCA, ischemia on EST was highly specific of an underlying ischemic substrate. These findings challenge the traditional belief that EST has a high false positive rate.

ChaMP-CMD: A Phenotype-Blinded, Randomized Controlled, Cross-Over Trial

BACKGROUND

Angina with nonobstructive coronary arteries is a common condition for which no effective treatment has been established. We hypothesized that the measurement of coronary flow reserve (CFR) allows identification of patients with angina with nonobstructive coronary arteries who would benefit from anti-ischemic therapy.

METHODS

Patients with angina with nonobstructive coronary arteries underwent blinded invasive CFR measurement and were randomly assigned to receive 4 weeks of amlodipine or ranolazine. After a 1-week washout, they crossed over to the other drug for 4 weeks; final assessment was after the cessation of study medication for another 4 weeks. The primary outcome was change in treadmill exercise time, and the secondary outcome was change in Seattle Angina Questionnaire summary score in response to anti-ischemic therapy. Analysis was on a per protocol basis according to the following classification: coronary microvascular disease (CMD group) if CFR<2.5 and reference group if CFR≥2.5. The study protocol was registered before the first patient was enrolled (International Standard Randomised Controlled Trial Number: ISRCTN94728379).

RESULTS

Eighty-seven patients (61±8 years of age; 62% women) underwent random assignment (57 CMD group and 30 reference group). Baseline exercise time and Seattle Angina Questionnaire summary scores were similar between groups. The CMD group had a greater increment (delta) in exercise time than the reference group in response to both amlodipine (difference in delta, 82 s [95% CI, 37-126 s]; P<0.001) and ranolazine (difference in delta, 68 s [95% CI, 21-115 s]; P=0.005). The CMD group reported a greater increment (delta) in Seattle Angina Questionnaire summary score than the reference group in response to ranolazine (difference in delta, 7 points [95% CI, 0-15]; P=0.048), but not to amlodipine (difference in delta, 2 points [95% CI, -5 to 8]; P=0.549).

CONCLUSIONS

Among phenotypically similar patients with angina with nonobstructive coronary arteries, only those with an impaired CFR derive benefit from anti-ischemic therapy. These findings support measurement of CFR to diagnose and guide management of this otherwise heterogeneous patient group.

Characterizing Mechanisms of Ischemia in Patients With Myocardial Bridges

BACKGROUND

Myocardial bridges (MBs) are prevalent and can be associated with acute and chronic ischemic syndromes. We sought to determine the substrates for ischemia in patients with angina with nonobstructive coronary arteries and a MB in the left anterior descending artery.

METHODS

Patients with angina with nonobstructive coronary arteries underwent the acquisition of intracoronary pressure and flow during rest, supine bicycle exercise, and adenosine infusion. Coronary wave intensity analysis was performed, with perfusion efficiency defined as accelerating wave energy/total wave energy (%). Epicardial endothelial dysfunction was defined as a reduction in epicardial vessel diameter ≥20% in response to intracoronary acetylcholine infusion. Patients with angina with nonobstructive coronary arteries and a MB were compared with 2 angina with nonobstructive coronary arteries groups with no MB: 1 with coronary microvascular disease (CMD: coronary flow reserve, <2.5) and 1 with normal coronary flow reserve (reference: coronary flow reserve, ≥2.5).

RESULTS

Ninety-two patients were enrolled in the study (30 MB, 33 CMD, and 29 reference). Fractional flow reserve in these 3 groups was 0.86±0.05, 0.92±0.04, and 0.94±0.05; coronary flow reserve was 2.5±0.5, 2.0±0.3, and 3.2±0.6. Perfusion efficiency increased numerically during exercise in the reference group (65±9%-69±13%; P=0.063) but decreased in the CMD (68±10%-50±10%; P<0.001) and MB (66±9%-55±9%; P<0.001) groups. The reduction in perfusion efficiency had distinct causes: in CMD, this was driven by microcirculation-derived energy in early diastole, whereas in MB, this was driven by diminished accelerating wave energy, due to the upstream bridge, in early systole. Epicardial endothelial dysfunction was more common in the MB group (54% versus 29% reference and 38% CMD). Overall, 93% of patients with a MB had an identifiable ischemic substrate.

CONCLUSIONS

MBs led to impaired coronary perfusion efficiency during exercise, which was due to diminished accelerating wave energy in early systole compared with the reference group. Additionally, there was a high prevalence of endothelial and microvascular dysfunction. These ischemic mechanisms may represent distinct treatment targets.

The application of dual-heart nursing mode in patients with coronary heart disease and angina pectoris and its impact on anxiety, depression, and quality of life

To diagnose and treat patients with coronary heart disease and angina pectoris with dual heart care mode and analyze the treatment effect. Three hundred cases meeting the inclusion criteria were equally divided into 3 groups, each containing 50 male and female cases. The patients in experimental group 1 took the dual heart nursing method proposed by the subject; experimental group 2 received betastatins; control group received conventional treatment. After 12 weeks of treatment, Hamilton depression scale scored the 3 groups, and their anxiety and depression scores, clinical manifestations, symptom scores and self-acceptance were analyzed. The chi square value of these data was compared with P, and judge whether they meet the needs and differences of statistical data. Then compare their scores before and after treatment to identify the treatment status. The anxiety and depression scores of experimental group 1 were the lowest among the 3 groups, with the values of 59.62 ± 7.925 and 58.64 ± 6.416; The total patients who responded effectively to treatment in experimental group 1 accounted for 83%, and the patients who responded effectively to treatment rate was the highest in the 3 groups; The effect of decreasing the score of complications in experimental group 1 was also the most obvious, from 9.07 ± 4.28 to 3.14 ± 2.07, which was the best in the 3 groups; the self-evaluation of patients in experimental group 1 was the highest among the 3 groups, 89.72 ± 4.28. The proposed dual heart care and treatment method can effectively treat coronary heart disease and angina pectoris, and can effectively improve the clinical performance and self-acceptance of patients. It can effectively restore the anxiety and depression of patients after treatment, and then improve patients' life quality, which has the value of popularization and use.

The change of angina levels in patients with chronic coronary syndromes and coronary microcirculatory dysfunction - a prospective study with 24 months follow-up

Introduction

A substantial proportion of patients with chronic coronary syndromes suffer from angina even after medical treatment and revascularization. Coronary microvascular dysfunction (CMD) is discussed as a potential mechanism.

Aim

To assess angina status in patients with chronic coronary syndromes undergoing functional assessment of coronary circulation regarding the presence of coronary microcirculatory dysfunction.

Material and methods

The study included 101 consecutive patients referred for coronary angiography requiring functional stenosis assessment, with median age of 66 years, 74% male, diagnosed or treated for dyslipidemia (91%) and diabetes type 2 (42%), 20% with a history of prior non-ST myocardial infarction. Fractional flow reserve (FFR), coronary flow reserve (CFR), resistive reserve ratio (RRR), and index of microcirculatory resistance (IMR) were measured. The diagnosis of CMD was defined by either IMR ≥ 25 units or CFR ≤ 2.0 in case of no significant stenosis. A change of one CCS class over 24 months follow-up was considered clinically significant.

Results

In patients without CMD diagnosis, there was a significant decrease in angina intensity (p < 0.001). Lack of angina improvement was associated with lower median RRR (2.30 (1.70, 3.30) vs. 3.05 (2.08, 4.10), p = 0.004) and lower median CFR (1.90 (1.40, 2.50) vs. 2.30 (IQR: 1.60, 3.00), p = 0.021), as compared to patients with angina improvement.

Conclusions

The presence of CMD is a risk factor for no angina improvement. Impaired coronary resistive reserve ratio and lower microvascular reactivity may be one of the pathomechanisms leading to the lack of angina improvement in patients with chronic coronary syndromes.

Coronary microvascular resistance comparison of coronary arteries with and without considering vascular diameter: A retrospective, single-center study

Background and Aims

Measurement of coronary microvascular resistance (MR) is essential for diagnosing nonocclusive coronary artery ischemia, but whether coronary branches of different diameters can be similarly assessed using hyperemic microvascular resistance index (hMVRI) calculated from average peak velocity (APV) remains unclear. We investigated the relationship between coronary arteries of different diameters and hMVRI.

Methods

Thirty patients with suspected angina pectoris and nonobstructive coronary stenosis with fractional flow reserve >0.8 underwent evaluation of all coronary arteries using a Doppler velocity and pressure-equipped guidewire. Quantitative coronary angiography (QCA) was used to analyze vessel diameter (DQCA). Coronary blood flow (CBFQCA) was calculated as πDQCA 2/4 (0.5 × APV) and hMVRIQCA as distal coronary pressure divided by CBFQCA during maximal hyperemia.

Results

The hMVRI was significantly higher for the right coronary artery than for the left anterior descending artery, but no significant differences between arteries were seen for CBFQCA and hMVRIQCA. Although the correlation between CBFQCA and APV was weak, CBFQCA divided into three groups according to DQCA showed very strong correlations with APV. Slopes of the straight line between APV and CBFQCA for small-, middle-, and large-diameter groups were 0.48, 0.30, and 0.21, respectively, with slope decreasing as diameter increased.

Conclusions

Comparative evaluation of MR in coronary branches with varying vessel diameters requires vessel diameter to be accounted for.

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 heart failure with preserved ejection fraction: what are the mechanistic links?

PURPOSE OF REVIEW

Heart failure with preserved ejection fraction (HFpEF) accounts for half of all heart failure presentations and is associated with a dismal prognosis. HFpEF is an umbrella term that constitutes several distinct pathophysiological entities. Coronary microvascular dysfunction (CMD), defined as the inability of the coronary vasculature to augment blood flow adequately in the absence of epicardial coronary artery disease, is highly prevalent amongst the HFpEF population and likely represents one distinct HFpEF endotype, the CMD-HFpEF endotype. This review appraises recent studies that have demonstrated an association between CMD and HFpEF with an aim to understand the pathophysiological links between the two. This is of significant clinical relevance as better understanding of the pathophysiology underlying CMD-HFpEF may result in more targeted and efficacious therapeutic options in this patient cohort.

RECENT FINDINGS

There is a high prevalence of CMD, diagnosed invasively or noninvasively, in patients with HFpEF. Patients with HFpEF who have an impaired myocardial perfusion reserve (MPR) have a worse outcome than those with a normal MPR. Both MPR and coronary flow reserve (CFR) are associated with measures of left ventricular diastolic function and left ventricular filling pressures during exercise. Impaired lusitropy and subendocardial ischaemia link CMD and HFpEF mechanistically.

SUMMARY

CMD-HFpEF is a prevalent endotype of HFpEF and one that is associated with adverse cardiovascular prognosis. Whether CMD leads to HFpEF, through subendocardial ischaemia, or whether it is secondary to the impaired lusitropy that is characteristic of HFpEF is not known. Further mechanistic work is needed to answer this pertinent question.

Endothelial cell dysfunction in cardiac disease: driver or consequence?

The vascular endothelium is a multifunctional cellular system which directly influences blood components and cells within the vessel wall in a given tissue. Importantly, this cellular interface undergoes critical phenotypic changes in response to various biochemical and hemodynamic stimuli, driving several developmental and pathophysiological processes. Multiple studies have indicated a central role of the endothelium in the initiation, progression, and clinical outcomes of cardiac disease. In this review we synthesize the current understanding of endothelial function and dysfunction as mediators of the cardiomyocyte phenotype in the setting of distinct cardiac pathologies; outline existing in vivo and in vitro models where key features of endothelial cell dysfunction can be recapitulated; and discuss future directions for development of endothelium-targeted therapeutics for cardiac diseases with limited existing treatment options.

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.

Coronary Microvascular Disease in Contemporary Clinical Practice

Coronary microvascular disease (CMD) causes myocardial ischemia in a variety of clinical scenarios. Clinical practice guidelines support routine testing for CMD in patients with ischemia with nonobstructive coronary artery disease. Invasive testing to identify CMD requires Doppler or thermodilution measures of flow to determine the coronary flow reserve and measures of microvascular resistance. Acetylcholine coronary reactivity testing identifies concomitant endothelial dysfunction, microvascular spasm, or epicardial coronary spasm. Comprehensive testing may improve symptoms, quality of life, and patient satisfaction by establishing a diagnosis and guiding-targeted medical therapy and lifestyle measures. Beyond ischemia with nonobstructive coronary artery disease, testing for CMD may play a role in patients with acute myocardial infarction, angina following coronary revascularization, heart failure with preserved ejection fraction, Takotsubo syndrome, and after heart transplantation. Additional education and provider awareness of CMD and its role in cardiovascular disease is needed to improve patient-centered outcomes of ischemic heart disease.

Protection against Ischemic Heart Disease: A Joint Role for eNOS and the KATP Channel

Genetic susceptibility may influence ischemic heart disease (IHD) predisposition and affect coronary blood flow (CBF) regulation mechanisms. The aim of this study was to investigate the association among single nucleotide polymorphisms (SNPs) of genes encoding for proteins involved in CBF regulation and IHD. A total of 468 consecutive patients were enrolled and divided into three groups according to coronary angiography and intracoronary functional tests results: G1, patients with coronary artery disease (CAD); G2, patients with coronary microvascular dysfunction (CMD); and G3, patients with angiographic and functionally normal coronary arteries. A genetic analysis of the SNPs rs5215 of the potassium inwardly rectifying channel subfamily J member 11 (KCNJ11) gene and rs1799983 of the nitric oxide synthase 3 (NOS3) gene, respectively encoding for the Kir6.2 subunit of ATP sensitive potassium (K_ATP) channels and nitric oxide synthase (eNOS), was performed on peripheral whole blood samples. A significant association of rs5215_G/G of KCNJ11 and rs1799983_T/T of NOS3 genes was detected in healthy controls compared with CAD and CMD patients. Based on univariable and multivariable analyses, the co-presence of rs5215_G/G of KCNJ11 and rs1799983_T/T of NOS3 may represent an independent protective factor against IHD, regardless of cardiovascular risk factors. This study supports the hypothesis that SNP association may influence the crosstalk between eNOS and the K_ATP channel that provides a potential protective effect against IHD.

Coronary Microvascular Spasm: Clinical Presentation and Diagnosis

Professor Maseri pioneered the research and treatment of coronary vasomotion abnormalities represented by coronary vasospasm and coronary microvascular dysfunction (CMD). These mechanisms can cause myocardial ischaemia even in the absence of obstructive coronary artery disease, and have been appreciated as an important aetiology and therapeutic target with major clinical implications in patients with ischaemia with non-obstructive coronary artery disease (INOCA). Coronary microvascular spasm is one of the key mechanisms responsible for myocardial ischaemia in patients with INOCA. Comprehensive assessment of coronary vasomotor reactivity by invasive functional coronary angiography or interventional diagnostic procedure is recommended to identify the underlying mechanisms of myocardial ischaemia and to tailor the best treatment and management based on the endotype of INOCA. This review highlights the pioneering works of Professor Maseri and contemporary research on coronary vasospasm and CMD with reference to endothelial dysfunction, Rho-kinase activation and inflammation.

Global trend and future landscape of coronary microcirculation: A bibliometric and visualized analysis from 1990 to 2021

Background

Coronary microcirculation has a fundamental role in the regulation of coronary blood flow in response to cardiac requirements, which has aroused wide concerns in basic science and clinical cardiovascular research. We aimed to analyze coronary microcirculation-associated literatures over 30 years and provide insightful information on the evolutionary path, frontier research hotspots, and future developmental trends.

Methods

Publications were retrieved from the Web of Science Core Collection (WoSCC). VOSviewer was used to perform co-occurrence analyses for countries, institutions, authors, and keywords and to generate visualized collaboration maps. CiteSpace was used to visualize the knowledge map derived from reference co-citation analysis, burst references, and keywords detection.

Results

This analysis was performed based on 11,702 publications including 9981 articles and 1721 reviews. The United States and Harvard University ranked at the top among all the countries and institutions. The majority of articles were published in Circulation, and it also was the most co-cited journal. Thematic hotspots and frontiers were focused on coronary microvascular dysfunction, magnetic resonance imaging, fractional flow reserve, STEMI, and heart failure. Additionally, keywords burst and co-occurrence cluster analysis showed that management, microvascular dysfunction, microvascular obstruction, prognostic value, outcomes, and guidelines were current knowledge gaps and future directions.

Conclusions

Coronary microcirculation presented a research hotspot relevant wide spectrum of cardiovascular diseases. Definite diagnostics and prognostics are particularly valued. The protection of cardiovascular events that influence clinical outcomes should be an insightful concern in the future. Multidisciplinary collaborations will provide significant advances for the development of coronary microcirculation.

Evolving concepts of the vulnerable atherosclerotic plaque and the vulnerable patient: implications for patient care and future research

Understanding the natural history of coronary artery atherosclerosis is necessary to determine prognosis and prescribe effective therapies. Traditional management of coronary artery disease has focused on the treatment of flow-limiting anatomical obstructions that lead to ischaemia. In most scenarios, revascularization of these atherosclerotic plaques has not substantially improved freedom from death or myocardial infarction, questioning the utility of contemporary revascularization strategies to improve prognosis. Advances in non-invasive and invasive imaging techniques have helped to identify the characteristics of obstructive and non-obstructive plaques that are precursors for plaque progression and future acute coronary syndromes as well as cardiac death. These 'vulnerable plaques' develop as a consequence of systemic inflammation and are prone to inducing thrombosis. Vulnerable plaques most commonly have a large plaque burden with a well-formed necrotic core and thin fibrous cap and are metabolically active. Perivascular adipose tissue might, in some patients, be used as a surrogate for coronary inflammation and predict future risk of adverse cardiac events. Vulnerable plaques can be identified in their quiescent state, offering the potential for therapeutic passivation. In this Review, we describe the biological and compositional features of vulnerable plaques, the non-invasive and invasive diagnostic modalities to characterize vulnerable plaques, the prognostic utility of identifying vulnerable plaques, and the future studies needed to explore the value of intensified pharmacological and focal treatments of vulnerable plaques.

The value of myocardial work in the estimation of left ventricular systolic function in patients with coronary microvascular disease: A study based on adenosine stress echocardiography

Background

Coronary microvascular dysfunction (CMD) is associated with increased cardiovascular events in patients with angina with non-obstructive coronary (ANOCA), especially heart failure. Conventional echocardiography is difficult to identify early alterations in cardiac function due to CMD.

Methods

We recruited 78 ANOCA patients. All patients underwent conventional echocardiography examination, adenosine stress echocardiography and examination of coronary flow reserve (CFR) by transthoracic echocardiography. Based on the CFR results, patients were divided into the CMD group (CFR < 2.5) and the non-CMD group (CFVR ≥ 2.5). Demographic data, conventional echocardiographic parameters, two-dimensional speckle-tracking echocardiography (2D-STE) parameters and myocardial work (MW) were compared between the two groups at rest and at stress. Logistic regression was used to analyze the factors associated with CMD.

Results

There was no significant difference in conventional echocardiography parameters, 2D-STE related indices or MW at rest between the two groups. Global work index (GWI), global contractive work (GCW), and global work efficiency (GWE) were lower in the CMD group than in the non-CMD group at stress (p = 0.040, 0.044, <0.001, respectively), but global waste work (GWW) and peak strain dispersion (PSD) were higher (both p < 0.001). GWI and GCW were associated with systolic blood pressure, diastolic blood pressure, product of heart rate and blood pressure, GLS and coronary flow velocity. While GWW was mainly correlated with PSD, GWE was correlated with PSD and GLS. In the non-CMD group, the responses to adenosine was mainly manifested as an increase in GWI, GCW and GWE (p = 0.001, 0.001, 0.009, respectively) and a decrease in PSD and GWW (p = 0.001, 0.015, respectively). In the CMD group, the response to adenosine was mainly manifested as an increase in GWW and a decrease in GWE (p = 0.002, and 0.006, respectively). In the multivariate regression analysis, we found that ΔGWW (difference in GWW before vs. after adenosine stress) and ΔPSD (difference in PSD before vs. after adenosine stress) were independent factors associated with CMD. The ROC curves showed that the composite prediction model consisting of ΔGWW and ΔPSD had excellent diagnostic value for CMD (area under the curve = 0.913).

Conclusion

In the present study, we found that CMD caused deterioration of myocardial work in ANOCA patients under adenosine stress, and that increased cardiac contraction asynchrony and wasted work may be the main changes caused by CMD.

Validation of pressure-bounded coronary flow reserve using invasive coronary physiologic assessment

Coronary flow reserve (CFR) represents entire coronary compensatory capacity. While CFR assessment is recommended to identify patients at an increased risk of cardiovascular events and coronary microvascular dysfunction, invasive CFR measurement is often technically challenging. Although not well validated yet, pressure-bounded CFR (pbCFR) has been proposed as a simple surrogate to estimate impaired CFR. In this study, we evaluated coronary physiological characteristics of low pbCFR using detailed invasive assessment. Invasive physiological assessment including resting ratio of distal coronary pressure to aortic pressure (Pd/Pa), fractional flow reserve (FFR), resting and hyperemic mean transit time, index of microcirculatory resistance (IMR), CFR, resistive reserve ratio, and microvascular resistance reserve (MRR) was performed in 107 patients in the left anterior descending coronary artery. pbCFR was calculated only with resting Pd/Pa and FFR. Patients were divided into low pbCFR and non-low pbCFR groups. Of 107 patients, 50 (46.7%) had low pbCFR. FFR (0.90 ± 0.05 vs. 0.83 ± 0.05, p < 0.001), hyperemic mean transit time (0.27 ± 0.17 vs. 0.21 ± 0.12, p = 0.04), and IMR (20.4 ± 13.2 vs. 15.0 ± 9.1, p = 0.01) were significantly higher in the low pbCFR group than their counterpart. While directly measured CFR did not differ significantly (4.4 ± 2.3 vs. 5.1 ± 2.8, p = 0.18), MRR was lower in the low pbCFR group (5.4 ± 3.0 vs. 6.8 ± 3.8, p = 0.047). The rates of CFR < 2.0 and IMR ≥ 25 were not significantly different between the 2 groups. In conclusion, although CFR did not differ significantly, IMR and MRR were impaired in patients with low pbCFR, suggesting pbCFR as a potential surrogate of coronary microvascular function in clinical practice.

Coronary endothelial dysfunction: from pathogenesis to clinical implications

Endothelial dysfunction (ED) has a substantial role in the pathogenesis of atherosclerosis and other vascular diseases. Multiple risk factors, including smoking, hyperlipiadaemia and diabetes, can have associated ED, which is correlated with cardiac events. Measurement of coronary artery endothelial function requires the use of invasive techniques to assess both epicardial coronary artery and microvascular beds. Peripheral vascular techniques and endothelial biomarkers can be used to indirectly assess coronary ED. In this review of coronary artery ED, we discuss the current state of the field, the techniques used to measure ED and its clinical implications.

Angina in 2022: Current Perspectives

Angina is the main symptom of ischemic heart disease; mirroring a mismatch between oxygen supply and demand. Epicardial coronary stenoses are only responsible for nearly half of the patients presenting with angina; whereas in several cases; symptoms may underlie coronary vasomotor disorders; such as microvascular dysfunction or epicardial spasm. Various medications have been proven to improve the prognosis and quality of life; representing the treatment of choice in stable angina and leaving revascularization only in particular coronary anatomies or poorly controlled symptoms despite optimal medical therapy. Antianginal medications aim to reduce the oxygen supply-demand mismatch and are generally effective in improving symptoms; quality of life; effort tolerance and time to ischemia onset and may improve prognosis in selected populations. Since antianginal medications have different mechanisms of action and side effects; their use should be tailored according to patient history and potential drug-drug interactions. Angina with non-obstructed coronary arteries patients should be phenotyped with invasive assessment and treated accordingly. Patients with refractory angina represent a higher-risk population in which some therapeutic options are available to reduce symptoms and improve quality of life; but robust data from large randomized controlled trials are still lacking.

Sex Differences in Acute Coronary Syndromes: A Global Perspective

Despite increasing evidence and improvements in the care of acute coronary syndromes (ACS), sex disparities in presentation, comorbidities, access to care and invasive therapies remain, even in the most developed countries. Much of the currently available data are derived from more developed regions of the world, particularly Europe and the Americas. In contrast, in more resource-constrained settings, especially in Sub-Saharan Africa and some parts of Asia, more data are needed to identify the prevalence of sex disparities in ACS, as well as factors responsible for these disparities, particularly cultural, socioeconomic, educational and psychosocial. This review summarizes the available evidence of sex differences in ACS, including risk factors, pathophysiology and biases in care from a global perspective, with a focus on each of the six different World Health Organization (WHO) regions of the world. Regional trends and disparities, gaps in evidence and solutions to mitigate these disparities are also discussed.

Vasospastic Angina: A Contemporary Review of its Pathophysiology, Diagnosis and Management

Nearly 40% of patients presenting to the catheter laboratory with angina have non-obstructed coronary arteries (ANOCA), an umbrella term that encompasses distinct pathophysiological entities, such as coronary artery spasm. Coronary artery spasm leads to sudden reversible coronary flow attenuation, which clinically manifests as vasospastic angina (VSA). VSA is associated with poor quality of life and an increased risk of major adverse cardiac events. However, the pathophysiological mechanisms underlying this phenomenon are incompletely understood, which has resulted in limited therapeutic options for patients afflicted with this condition. The past decade has seen a surge in new research being conducted in the field of ANOCA and VSA. This review article provides a comprehensive summary of the underlying pathophysiological mechanisms of VSA and the current therapeutic options. We also appraise the current diagnostic approach in patients with suspected VSA.

Complete Blood Count-Derived Indices as Prognostic Factors of 5-Year Outcomes in Patients With Confirmed Coronary Microvascular Spasm

Background

Coronary microcirculatory dysfunction is a meaningful factor in the development of ischemic heart disease. We investigated the relationship between coronary microvascular spasm and complete blood count indices.

Methods

Between 2010 and 2013, we performed acetylcholine test (AChT) in subjects with suspicion of angina evoked by epicardial coronary spasm or coronary microvascular spasm according to COVADIS criteria. We administered acetylcholine in increasing doses of 25, 50, and 75 μg into the right coronary artery and 25, 50, and 100 μg into the left coronary artery. Patients were followed up for 60 months.

Results

In total, 211 patients (60.5 ± 7.8 years, 67.8% women) were included in the study. The AChT revealed angina due to epicardial coronary spasm in 99 patients (46.9%) and coronary microvascular spasm in 72 (34.1%). White blood cell (WBC), red blood cell distribution width (RDW), platelets (PLT), mean platelet volume (MPV), and platelet distribution width (PDW) values were significantly higher in patients with coronary microvascular spasm than in patients from the other two groups, i.e., epicardial coronary spasm and negative AChT. PDW showed the highest sensitivity (65%) and specificity (72%) at the cutoff value of 15.32% [area under the curve, 0.723; 95% confidence interval (CI) 0.64-0.83; P < 0.001]. Independent risk factors for coronary microvascular spasm diagnosis using AChT were as follows: female sex (OR, 1.199), PDW (OR, 2.891), and RDW (OR, 1.567).

Conclusion

PDW and RDW are significantly associated with the diagnosis of coronary microvascular spasm in patients undergoing AChT as well as with poor prognosis in such patients at 5 years.