Pharmacotherapy for coronary microvascular dysfunction

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.

"The INOCA-IT: Rationale and design of a multicenter registry investigating ischemia in patients with non-obstructive coronary artery (INOCA) disease in Italy"

BACKGROUND

Ischemia with non-obstructive coronary artery (INOCA) disease is being progressively acknowledged as one of the pathophysiological mechanisms of chronic coronary syndrome (CCS) in an increasingly wide range of clinical pictures. Although the research has already begun to move towards a defined diagnostic pathway and a specific medical therapy for this disease, at present it remains a clinical challenge, especially if not thoroughly investigated.

METHODS AND RESULTS

The INOCA IT Multicenter Registry RF-2019-12369486 is a prospective, multicentric, non-randomized, single-arm, open label clinical study which aims to evaluate the efficacy of a stratified diagnostic and therapeutic approach on adverse events prevention and symptom relief in Italian patients with INOCA disease. The study population includes patients with a clinical presentation of CCS for angina and/or positive stress test for myocardial ischemia and evidence of non-obstructive coronary artery disease (CAD) at coronary angiography. In these patients a complete invasive coronary physiology assessment is performed with the guidewire-based measurement of coronary flow reserve (CFR) and index of microvascular resistance (IMR), followed by acetylcholine (ACh) spasm provocation test. On the basis of the results of coronary function testing, patients are stratified into different INOCA endotypes (coronary microvascular disease, vasospastic angina, microvascular spasm, non-cardiac chest pain) and given a tailored medical therapy in accordance with the latest scientific evidence. At one year follow-up the impact of such a target therapy on angina class and quality of life, as well as on cardiovascular adverse events (hospitalization and coronary revascularization) is evaluated.

CONCLUSIONS

The INOCA-IT Multicenter Registry will inform clinicians on sex-specific prevalence of INOCA in Italy and will show the impact of a stratified diagnostic and therapeutic approach on symptoms burden and prognosis of INOCA patients.

Coronary Vasomotor Dysfunction Is Associated With Cardiovascular Events in Patients With Nonobstructive Coronary Artery Disease

BACKGROUND

Coronary vasomotor dysfunction (CVDys) can be comprehensively classified on the basis of anatomy and functional mechanisms.

OBJECTIVES

The aim of this study was to evaluate the association between different CVDys phenotypes and outcomes in patients with angina and nonobstructive coronary artery disease (ANOCA).

METHODS

Patients with ANOCA who underwent coronary reactivity testing using an intracoronary Doppler guidewire to assess microvascular and epicardial coronary endothelium-dependent and endothelium-independent function were enrolled. Endothelium-dependent microvascular and epicardial coronary dysfunction were defined as a <50% change in coronary blood flow in response to intracoronary acetylcholine (Ach) infusion and a <-20% change in coronary artery diameter in response to Ach. Endothelium-independent microvascular and epicardial coronary dysfunction were defined as coronary flow reserve < 2.5 during adenosine-induced hyperemia and change in cross-sectional area in response to intracoronary nitroglycerin administration < 20%. Major adverse cardiac and cerebrovascular events (cardiovascular death, nonfatal MI, heart failure, stroke, and late revascularization) served as clinical outcomes.

RESULTS

Among the 1,196 patients with ANOCA, the prevalence of CVDys was 24.5% and 51.8% among those with endothelium-independent and endothelium-dependent microvascular dysfunction, respectively, and 47.4% and 25.4% among those with endothelium-independent and endothelium-dependent epicardial coronary dysfunction, respectively. During 6.3 years (Q1-Q3: 2.5-12.9 years) of follow-up, patients with endothelium-dependent microvascular dysfunction, endothelium-dependent epicardial coronary dysfunction, or endothelium-independent microvascular dysfunction showed significantly higher event rates compared with those without (19.5% vs 12.0% [P < 0.001], 19.7% vs 14.6% [P = 0.038] and 22.2% vs 13.8% [P = 0.001], respectively). Coronary flow reserve (HR: 0.757; 95% CI: 0.604-0.957) and percentage change in coronary blood flow in response to Ach infusion (HR: 0.998; 95% CI: 0.996-0.999) remained significant predictors of major adverse cardiac and cerebrovascular event after adjustment for conventional risk factors.

CONCLUSIONS

CVDys phenotype is differentially associated with worse outcomes, and endothelium-dependent and endothelium-independent microvascular function provide independent prognostic information in patients with ANOCA.

Clinical aspects of ischemia with no obstructive coronary artery disease (INOCA)

Ischemia with no obstructive coronary arteries (INOCA) is defined as patients with evidence of myocardial ischemia without obstructive coronary artery disease. About 3-4 million people in the United States have INOCA, more commonly affecting women, and carries adverse morbidity, mortality, and relatively high healthcare costs. The pathophysiology of INOCA appears to be multi-factorial with a variety of contributing mechanisms. Diagnosis of INOCA is suggested by non-invasive or invasive testing consistent with myocardial ischemia. Due to the high prevalence of coronary risk factors and atherosclerosis in the INOCA population, current treatment strategies target angina, coronary atherosclerosis, and atherosclerotic risk factors, as well as burgeoning treatment of coronary microvascular dysfunction (CMD). Ongoing clinical trials are assessing different options.

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.

Chinese expert consensus on the diagnosis and treatment of coronary microvascular diseases (2023 Edition)

Since the four working groups of the Chinese Society of Cardiology issued first expert consensus on coronary microvascular diseases (CMVD) in 2017, international consensus documents on CMVD have increased rapidly. Although some of these documents made preliminary recommendations for the diagnosis and treatment of CMVD, they did not provide classification of recommendations and levels of evidence. In order to summarize recent progress in the field of CMVD, standardize the methods and procedures of diagnosis and treatment, and identify the scientific questions for future research, the four working groups of the Chinese Society of Cardiology updated the 2017 version of the Chinese expert consensus on CMVD and adopted a series of measures to ensure the quality of this document. The current consensus has raised a new classification of CMVD, summarized new epidemiological findings for different types of CMVD, analyzed key pathological and molecular mechanisms, evaluated classical and novel diagnostic technologies, recommended diagnostic pathways and criteria, and therapeutic strategies and medications, for patients with CMVD. In view of the current progress and knowledge gaps of CMVD, future directions were proposed. It is hoped that this expert consensus will further expedite the research progress of CMVD in both basic and clinical scenarios.

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.

The role of imaging in the selection of patients for HFpEF therapy

Heart failure with preserved ejection fraction (HFpEF) traditionally has been characterized as a form of heart failure without therapeutic options, in particular with a lack of response to the established therapies of heart failure with reduced ejection fraction (HFrEF). However, this is no longer true. Besides physical exercise, risk factor modification, aldosterone blocking agents, and sodium-glucose cotransporter 2 inhibitors, specific therapies are emerging for specific HFpEF etiologies, such as hypertrophic cardiomyopathy or cardiac amyloidosis. This development justifies increased efforts to arrive at specific diagnoses within the umbrella of HFpEF. Cardiac imaging plays by far the largest role in this effort and is discussed in the following review.

Shexiang Tongxin Dropping Pill alleviates M1 macrophage polarization-induced inflammation and endothelial dysfunction to reduce coronary microvascular dysfunction via the dectin-1/Syk/IRF5 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Shexiang Tongxin Dropping Pill (STDP), a traditional Chinese medicine compound, is fragrant, invigorates the qi, unblocks pulses, activates the blood circulation, removes blood stasis, and relieves pain. It is used clinically to treat coronary heart disease and angina pectoris. Coronary microvascular dysfunction (CMD) is associated with increased morbidity and mortality from cardiovascular events. Endothelial dysfunction and inflammation have been verified as its underlying causes. STDP can ameliorate CMD, but the mechanism has not been fully elucidated.

AIM OF THE STUDY

To explore the effects of STDP on M1 macrophage polarization-induced inflammation and endothelial dysfunction as an inhibitor of CMD, and to determine its mechanisms of action.

MATERIALS AND METHODS

The CMD rat model was established by left anterior descending artery (LAD) ligation. The efficacy of STDP against CMD was evaluated by echocardiography, optical microangiography, Evans blue staining, and histological examination. The OGD/R-induced endothelial injury model, the endothelial injury-induced sterile inflammation model, the Dectin-1 overexpression model, and the Dectin-1-overexpressing RAW264.7 macrophage supernatant-stimulated HUVEC-induced secondary injury of endothelial function model were established to confirm the efficacy of STDP against M1 macrophage polarization-induced inflammation and endothelial dysfunction.

RESULTS

STDP blunted the deterioration of cardiac function and ameliorated CMD by reducing inflammatory cell infiltration and endothelial dysfunction in CMD rats. Endothelial injury and Dectin-1 overexpression induced M1 macrophage polarization and inflammation. Mechanically, STDP hindered M1 macrophage polarization and inflammation by inhibiting the Dectin-1/Syk/IRF5 pathway both in vivo and in vitro. STDP alleviated endothelial dysfunction induced by Dectin-1 overexpression in macrophages.

CONCLUSION

STDP can alleviate M1 macrophage polarization-induced inflammation and endothelial dysfunction against CMD via the Dectin-1/Syk/IRF5 pathway. Dectin-1-associated M1 macrophage polarization might be developed as a novel target for ameliorating CMD.

Coronary microvascular dysfunction: A review of recent progress and clinical implications

The coronary microcirculation plays a cardinal role in regulating coronary blood flow to meet the changing metabolic demands of the myocardium. Coronary microvascular dysfunction (CMD) refers to structural and functional remodeling of the coronary microcirculation. CMD plays a role in the pathogenesis of obstructive and non-obstructive coronary syndromes as well as myocardial diseases, including heart failure with preserved ejection fraction (HFpEF). Despite recent diagnostic advancements, CMD is often under-appreciated in clinical practice, and may allow for the development of novel therapeutic targets. This review explores the diagnosis and pathogenic role of CMD across a range of cardiovascular diseases, its prognostic significance, and the current therapeutic landscape.

Effect of Proprietary Chinese Medicine on Coronary Microvascular Dysfunction in Patients with Microvascular Angina: A Systematic Review and Meta-Analysis

Background

Microvascular angina (MVA) has received increasing attention and interest in recent years, but there are still some shortcomings in the diagnosis and treatments at current stage. In recent years, several studies have confirmed the efficacy of proprietary Chinese medicines (PCMs) in improving MVA symptoms; however, there is no systematic review and meta-analysis to comprehensively assess the efficacy of PCMs in this area.

Objective

Investigating the clinical efficacy of proprietary Chinese medicines for treating MVA and coronary microvascular function.

Methods

We looked up articles from January 1, 2012, to the present from eight databases. Then, we screened the literature and followed the 2019 version 2 of Cochrane risk of bias tool for systematic review. The Stata/SE 15.0 software was used for the meta-analysis.

Results

There are 21 studies, including 1,641 patients who were included in this review. According to the results, the combination of PCMs and conventional MVA treatment was able to further enhance clinical efficacy [RR = 1.28, 95% CI (1.20, 1.36), p < 0.001], prolong the time of duration on the treadmill exercise testing (TET) [SMD = 1.49, 95% CI (0.63, 2.36), p = 0.001] and improve levels of NO [SMD = -1.77 95% CI (-2.11, -1.43), p < 0.001]. At the same time, PCMs could also decrease the microvascular resistance index (IMR) [SMD = -1.79, 95% CI (-2.58, -1.00), p < 0.001)], serum level of hs-CRP [SMD = -1.21, 95% CI (-1.84, -0.58), p < 0.001] and ET-1 [SMD = -1.77 95% CI (-2.11, -1.43), p < 0.001]. Regards to medication safety, a total of 27 adverse events occurred, including 10 cases in the intervention group and 17 cases in the control group.

Conclusion

The study suggests that the combination of PCMs and conventional MVA treatment enhances clinical efficacy and could better improve coronary microvascular function. In the future, we expect more high-quality, randomized, double-blind clinical studies to validate the safety, and efficacy of PCMs to provide valuable evidence-based medicine (EBM) for the treatment of MVA with PCMs.

Ischemia and no obstructive coronary arteries (INOCA): A narrative review

Myocardial ischemia with no obstructive coronary arteries (INOCA) is a chronic coronary syndrome condition that is increasingly being recognized as a substantial contributor to adverse cardiovascular mortality and outcomes, including myocardial infarction and heart failure with preserved ejection fraction (HFpEF). While INOCA occurs in both women and men, women are more likely to have the finding of INOCA and are more adversely impacted by angina, with recurrent hospitalizations and a lower quality of life with this condition. Abnormal epicardial coronary vascular function and coronary microvascular dysfunction (CMD) have been identified in a majority of INOCA patients on invasive coronary function testing. CMD can co-exist with obstructive epicardial coronary artery disease (CAD), diffuse non-obstructive epicardial CAD, and with coronary vasospasm. Epicardial vasospasm can also occur with normal coronary arteries that have no atherosclerotic plaque on intravascular imaging. While all predisposing factors are not clearly understood, cardiometabolic risk factors, and endothelium dependent and independent mechanisms that increase oxidative stress and inflammation are associated with microvascular injury, CMD and INOCA. Cardiac autonomic dysfunction has also been implicated in abnormal vasoreactivity and persistent symptoms. INOCA is under-recognized and under-diagnosed, partly due to the heterogenous patient populations and mechanisms. However, diagnostic testing methods are available to guide INOCA management. Treatment of INOCA is evolving, and focuses on cardiac risk factor control, improving ischemia, reducing atherosclerosis progression, and improving angina and quality of life. This review focuses on INOCA, relations to HFpEF, available diagnostics, current and investigational therapeutic strategies, and knowledge gaps in this condition.

Safety and prognostic relevance of acetylcholine testing in patients with stable myocardial ischaemia or myocardial infarction and non-obstructive coronary arteries

BACKGROUND

Intracoronary provocation testing with acetylcholine (ACh) is crucial for the diagnosis of functional coronary alterations in patients with suspected myocardial ischaemia and non-obstructive coronary arteries.

AIMS

Our intention was to assess the safety and predictive value for major adverse cardiovascular and cerebrovascular events (MACCE) in patients presenting with ischaemia with non-obstructive coronary arteries (INOCA) or with myocardial infarction with non-obstructive coronary arteries (MINOCA).

METHODS

We prospectively enrolled consecutive INOCA or MINOCA patients undergoing intracoronary ACh provocation testing.

RESULTS

A total of 317 patients were enrolled: 174 (54.9%) with INOCA and 143 (45.1%) with MINOCA. Of these, 185 patients (58.4%) had a positive response to the ACh test. Complications during ACh provocative testing were all mild and transient and occurred in 29 (9.1%) patients, with no difference between patients with positive or negative responses to ACh testing, nor between INOCA and MINOCA patients. A history of paroxysmal atrial fibrillation, moderate/severe diastolic dysfunction and a higher QT dispersion at baseline electrocardiogram were independent predictors of complications. MACCE occurred in 30 patients (9.5%) during a median follow-up of 22 months. The incidence of MACCE was higher among patients with a positive ACh test (24 [13.0%] vs 6 [4.5%], p=0.017), and a positive ACh test was an independent predictor of MACCE.

CONCLUSIONS

ACh provocation testing is associated with a low risk of mild and transient complications, with a similar prevalence in both INOCA and MINOCA patients. Importantly, ACh provocation testing can help to identify patients at higher risk of future clinical events, suggesting a net clinical benefit derived from its use in this clinical setting.

Pretreatment with Shenmai Injection Protects against Coronary Microvascular Dysfunction

Background

The clinical treatment of coronary microvascular dysfunction (CMD) is mainly based on conventional medicine, but the mechanism of the medicine is single and the efficacy is different. Shenmai injection (SMI) has a variety of ingredients, but the effect of SMI on CMD has not been studied. This study investigated the effect of SMI on CMD and its possible mechanism.

Methods

The protective effect of SMI on CMD was evaluated in Sprague-Dawley (SD) rats and human umbilical vein endothelial cells (HUVECs). In vivo, forty-five male SD rats were randomly divided into control group (sham group), CMD group (model group), and SMI group (treatment group). Two weeks after SMI intervention, laurate was injected into the left ventricle of rats to construct a CMD model. Blood samples were collected to detect myocardial enzymes, oxidative stress, and inflammatory factors, and the hearts of rats were extracted for histopathological staining and western blot detection. In vitro, a hydrogen peroxide-induced endothelial injury model was established in HUVECs. After pretreatment with SMI, cell viability, oxidative stress, vasodilative factors, and apoptosis were detected.

Results

In vivo, pretreatment with SMI could effectively reduce the concentrations of lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), cardiac troponin I (cTnI), endothelin-1 (ET-1), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and malondialdehyde (MDA) in the serum of rats. Meanwhile, the expression of bcl-2-associated X (Bax) and caspase-3 protein in the myocardium of rats was decreased in the SMI group. The levels of nitric oxide (NO) and superoxide dismutase (SOD) and the expression of B-cell lymphoma-2 (Bcl-2) were higher in the SMI group than in the CMD group. Pathological staining results showed that SMI could effectively reduce inflammatory infiltration and the formation of collagen fibers and microthrombus in the rat myocardium. In vitro, intervention with SMI could improve endothelial function in a dose-dependent manner as evidenced by increasing the activity of endothelial cells and the expression of NO, SOD, endothelial nitric oxide synthase (eNOS), and Bcl-2, while decreasing cell apoptosis and the levels of ET-1, MDA, Bax, and caspase-3.

Conclusions

Pretreatment with SMI could improve CMD by alleviating oxidative stress, inflammatory response, and apoptosis and then improving vascular endothelial function and microvascular structure.

Assessment and Treatment for Coronary Microvascular Dysfunction by Contrast Enhanced Ultrasound

With growing evidence in clinical practice, the understanding of coronary syndromes has gradually evolved out of focusing on the well-established link between stenosis of epicardial coronary artery and myocardial ischemia to the structural and functional abnormalities at the level of coronary microcirculation, known as coronary microvascular dysfunction (CMD). CMD encompasses several pathophysiological mechanisms of coronary microcirculation and is considered as an important cause of myocardial ischemia in patients with angina symptoms without obstructive coronary artery disease (CAD). As a result of growing knowledge of the understanding of CMD assessed by multiple non-invasive modalities, CMD has also been found to be involved in other cardiovascular diseases, including primary cardiomyopathies as well as heart failure with preserved ejection fraction (HFpEF). In the past 2 decades, almost all the imaging modalities have been used to non-invasively quantify myocardial blood flow (MBF) and promote a better understanding of CMD. Myocardial contrast echocardiography (MCE) is a breakthrough as a non-invasive technique, which enables assessment of myocardial perfusion and quantification of MBF, exhibiting promising diagnostic performances that were comparable to other non-invasive techniques. With unique advantages over other non-invasive techniques, MCE has gradually developed into a novel modality for assessment of the coronary microvasculature, which may provide novel insights into the pathophysiological role of CMD in different clinical conditions. Moreover, the sonothrombolysis and the application of artificial intelligence (AI) will offer the opportunity to extend the use of contrast ultrasound theragnostics.

A Practical Approach to Invasive Testing in Ischemia with No Obstructive Coronary Arteries (INOCA)

Up to 65% of women and approximately 30% of men have ischemia with no obstructive coronary artery disease (CAD; commonly known as INOCA) on invasive coronary angiography performed for stable angina. INOCA can be due to coronary microvascular dysfunction or coronary vasospasm. Despite the absence of obstructive CAD, those with INOCA have an increased risk of all-cause mortality and adverse outcomes, including recurrent angina and cardiovascular events. These patients often undergo repeat testing, including cardiac catheterization, resulting in lifetime healthcare costs that rival those for obstructive CAD. Patients with INOCA often remain undiagnosed and untreated. This review discusses the symptoms and prognosis of INOCA, offers a systematic approach to the diagnostic evaluation of these patients, and summarizes therapeutic management, including tailored therapy according to underlying pathophysiological mechanisms.

Mechanisms and clinical implications of endothelium-dependent vasomotor dysfunction in coronary microvasculature

Coronary microvascular disease (CMD), which affects the arterioles and capillary endothelium that regulate myocardial perfusion, is an increasingly recognized source of morbidity and mortality, particularly in the setting of metabolic syndrome. The coronary endothelium plays a pivotal role in maintaining homeostasis, though factors such as diabetes, hypertension, hyperlipidemia, and obesity can contribute to endothelial injury and consequently arteriolar vasomotor dysfunction. These disturbances in the coronary microvasculature clinically manifest as diminished coronary flow reserve, which is a known independent risk factor for cardiac death, even in the absence of macrovascular atherosclerotic disease. Therefore, a growing body of literature has examined the molecular mechanisms by which coronary microvascular injury occurs at the level of the endothelium and the consequences on arteriolar vasomotor responses. This review will begin with an overview of normal coronary microvascular physiology, modalities of measuring coronary microvascular function, and clinical implications of CMD. These introductory topics will be followed by a discussion of recent advances in the understanding of the mechanisms by which inflammation, oxidative stress, insulin resistance, hyperlipidemia, hypertension, shear stress, endothelial cell senescence, and tissue ischemia dysregulate coronary endothelial homeostasis and arteriolar vasomotor function.

Mechanisms and Clinical Implications of Endothelial Dysfunction in Arterial Hypertension

The endothelium is composed of a monolayer of endothelial cells, lining the interior surface of blood and lymphatic vessels. Endothelial cells display important homeostatic functions, since they are able to respond to humoral and hemodynamic stimuli. Thus, endothelial dysfunction has been proposed as a key and early pathogenic mechanism in many clinical conditions. Given the relevant repercussions on cardiovascular risk, the complex interplay between endothelial dysfunction and systemic arterial hypertension has been a matter of study in recent years. Numerous articles have been published on this issue, all of which contribute to providing an interesting insight into the molecular mechanisms of endothelial dysfunction in arterial hypertension and its role as a biomarker of inflammation, oxidative stress, and vascular disease. The prognostic and therapeutic implications of endothelial dysfunction have also been analyzed in this clinical setting, with interesting new findings and potential applications in clinical practice and future research. The aim of this review is to summarize the pathophysiology of the relationship between endothelial dysfunction and systemic arterial hypertension, with a focus on the personalized pharmacological and rehabilitation strategies targeting endothelial dysfunction while treating hypertension and cardiovascular comorbidities.

Coronary Microvascular Angina: A State-of-the-Art Review

Up to 60–70% of patients, undergoing invasive coronary angiography due to angina and demonstrable myocardial ischemia with provocative tests, do not have any obstructive coronary disease. Coronary microvascular angina due to a dysfunction of the coronary microcirculation is the underlying cause in almost 50% of these patients, associated with a bad prognosis and poor quality of life. In recent years, progress has been made in the diagnosis and management of this condition. The aim of this review is to provide an insight into current knowledge of this condition, from current diagnostic methods to the latest treatments.

A pathophysiological compass to personalize antianginal drug treatment

Myocardial ischaemia results from coronary macrovascular or microvascular dysfunction compromising the supply of oxygen and nutrients to the myocardium. The underlying pathophysiological processes are manifold and encompass atherosclerosis of epicardial coronary arteries, vasospasm of large or small vessels and microvascular dysfunction - the clinical relevance of which is increasingly being appreciated. Myocardial ischaemia can have a broad spectrum of clinical manifestations, together denoted as chronic coronary syndromes. The most common antianginal medications relieve symptoms by eliciting coronary vasodilatation and modulating the determinants of myocardial oxygen consumption, that is, heart rate, myocardial wall stress and ventricular contractility. In addition, cardiac substrate metabolism can be altered to alleviate ischaemia by modulating the efficiency of myocardial oxygen use. Although a universal agreement exists on the prognostic importance of lifestyle interventions and event prevention with aspirin and statin therapy, the optimal antianginal treatment for patients with chronic coronary syndromes is less well defined. The 2019 guidelines of the ESC recommend a personalized approach, in which antianginal medications are tailored towards an individual patient's comorbidities and haemodynamic profile. Although no antianginal medication improves survival, their efficacy for reducing symptoms profoundly depends on the underlying mechanism of the angina. In this Review, we provide clinicians with a rationale for when to use which compound or combination of drugs on the basis of the pathophysiology of the angina and the mode of action of antianginal medications.

Outpatient Management of Patients With Angina With No Obstructive Coronary Arteries: How to Come to a Proper Diagnosis and Therapy

Two-thirds of women and one-third of men who undergo a clinically indicated coronary angiography for stable angina, have no obstructive coronary artery disease (CAD). Coronary vascular dysfunction is a highly prevalent underlying cause of angina in these so called “Angina with No Obstructive Coronary Arteries (ANOCA)” patients, foremost in middle aged women. Coronary vascular dysfunction encompasses various endotypes, namely epicardial and microvascular coronary spasms, impaired vasodilatation, and increased microvascular resistance. ANOCA patients, especially those with underlying coronary vascular dysfunction, have an adverse cardiovascular prognosis, poor physical functioning, and a reduced quality of life. Since standard ischemia detection tests and coronary angiograms are not designed to diagnose coronary vascular dysfunction, this ischemic heart disease is often overlooked and hence undertreated. But adequate diagnosis is vital, so that treatment can be started to reduce symptoms, reduce healthcare costs and improve quality of life and cardiovascular prognosis. The purpose of this review is to give a contemporary overview of ANOCA with focus on coronary vascular dysfunction. We will provide a possible work-up of patients suspected of coronary vascular dysfunction in the outpatient clinical setting, based on the latest scientific insights and international consensus documents. We will discuss the value of ischemia detection testing, and non-invasive and invasive methods to diagnose coronary vascular dysfunction. Furthermore, we will go into pharmacological and non-pharmacological therapeutic options including anti-anginal regimens and lifestyle interventions.

Coronary Microvascular Dysfunction Across the Spectrum of Cardiovascular Diseases: JACC State-of-the-Art Review

Coronary microvascular dysfunction (CMD) encompasses several pathogenetic mechanisms involving coronary microcirculation and plays a major role in determining myocardial ischemia in patients with angina without obstructive coronary artery disease, as well as in several other conditions, including obstructive coronary artery disease, nonischemic cardiomyopathies, takotsubo syndrome, and heart failure, especially the phenotype associated with preserved ejection fraction. Unfortunately, despite the identified pathophysiological and prognostic role of CMD in several conditions, to date, there is no specific treatment for CMD. Due to the emerging role of CMD as common denominator in different clinical phenotypes, additional research in this area is warranted to provide personalized treatments in this "garden variety" of patients. The purpose of this review is to describe the pathophysiological mechanisms of CMD and its mechanistic and prognostic role across different cardiovascular diseases. We will also discuss diagnostic modalities and the potential therapeutic strategies resulting from recent clinical studies.

Acute Coronary Syndromes (ACS)-Unravelling Biology to Identify New Therapies-The Microcirculation as a Frontier for New Therapies in ACS

In acute coronary syndrome (ACS) patients, restoring epicardial culprit vessel patency and flow with percutaneous coronary intervention or coronary artery bypass grafting has been the mainstay of treatment for decades. However, there is an emerging understanding of the crucial role of coronary microcirculation in predicting infarct burden and subsequent left ventricular remodelling, and the prognostic significance of coronary microvascular obstruction (MVO) in mortality and morbidity. This review will elucidate the multifaceted and interconnected pathophysiological processes which underpin MVO in ACS, and the various diagnostic modalities as well as challenges, with a particular focus on the invasive but specific and reproducible index of microcirculatory resistance (IMR). Unfortunately, a multitude of purported therapeutic strategies to address this unmet need in cardiovascular care, outlined in this review, have so far been disappointing with conflicting results and a lack of hard clinical end-point benefit. There are however a number of exciting and novel future prospects in this field that will be evaluated over the coming years in large adequately powered clinical trials, and this review will briefly appraise these.

An EAPCI Expert Consensus Document on Ischaemia with Non-Obstructive Coronary Arteries in Collaboration with European Society of Cardiology Working Group on Coronary Pathophysiology & Microcirculation Endorsed by Coronary Vasomotor Disorders International Study Group

This consensus document, a summary of the views of an expert panel organized by the European Association of Percutaneous Cardiovascular Interventions (EAPCI), appraises the importance of ischaemia with non-obstructive coronary arteries (INOCA). Angina pectoris affects approximately 112 million people globally. Up to 70% of patients undergoing invasive angiography do not have obstructive coronary artery disease, more common in women than in men, and a large proportion have INOCA as a cause of their symptoms. INOCA patients present with a wide spectrum of symptoms and signs that are often misdiagnosed as non-cardiac leading to under-diagnosis/investigation and under-treatment. INOCA can result from heterogeneous mechanism including coronary vasospasm and microvascular dysfunction and is not a benign condition. Compared to asymptomatic individuals, INOCA is associated with increased incidence of cardiovascular events, repeated hospital admissions, as well as impaired quality of life and associated increased health care costs. This consensus document provides a definition of INOCA and guidance to the community on the diagnostic approach and management of INOCA based on existing evidence from research and best available clinical practice; noting gaps in knowledge and potential areas for further investigation.

Chronic Coronary Syndromes in Women: Challenges in Diagnosis and Management

Sex matters in science. This particularly applies to ischemic heart disease, which displays key differences in pathophysiology, presentation, and effectiveness in diagnostic strategies and management between women and men. However, underrepresentation of women in randomized trials has led to an evidence gap in clinical practice. Nevertheless, it has become clear that women present with a higher burden of symptoms and comorbidities, experience worse outcomes, but are less likely to have flow-limiting stenosis in epicardial coronary arteries than men. A major contributor to this paradox is coronary microvascular disease, a heterogeneous disorder with multifactorial etiology that predominantly affects women. There is a significant interplay between coronary microvascular disease, obstructive coronary artery disease, and the cardiovascular risk associated with it, with impaired vasomotor function often preceding the development of advanced atheroma. This novel concept has recently been referred to as chronic coronary syndromes, which better meets the female phenotype of ischemic heart disease, questioning current management recommendations that still largely apply to flow-limiting stenoses in epicardial coronary arteries typically found in men. The goal of this review is to highlight the most recent scientific advances in understanding chronic coronary syndromes in women. It provides practical advice with focus on challenges in diagnosis and management, and discusses perspectives towards the implementation of sex-specific, safer, and more effective therapeutic strategies.

Myocardial Infarction with Nonobstructive Coronary Artery Disease—Definition, Etiopathogenesis, Diagnosis, and Management

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is a complex clinical syndrome that is characterized by evidence of acute myocardial infarction in the absence of significant epicardial coronary artery disease on angiography. The term “MINOCA” encompasses a group of heterogeneous diseases with varying underlying mechanisms and each with its own pathophysiology. Overlooked plaque rupture or erosion and coronary vasospasm are the most common causes of MINOCA and can be diagnosed by routine intracoronary imaging and vasoreactivity testing, respectively. Coronary microvascular dysfunction is a less recognized, albeit an important cause of morbidity in patients presenting with MINOCA. Although MINOCA is a rare presentation of acute coronary syndrome, it is not a benign disorder and can have adverse consequences if untreated. In this article, we aim to review the pathogenesis, clinical characteristics, and finally propose a systematic approach in the diagnosis and management of patients with MINOCA.

Effect of Pravastatin Pretreatment and Hypercapnia on Intestinal Microvascular Oxygenation and Blood Flow During Sepsis

INTRODUCTION

In septic patients, adequate microvascular oxygenation (μHBO2) of the intestine is vital for their outcome. Recent studies suggest that statins can ameliorate septic microcirculation in a variety of tissues. However, the effect on intestinal microvascular oxygenation and blood flow is largely unknown. Furthermore, there are indications that statin therapy might not be beneficial in the presence of hypercapnia, as observed in septic acute respiratory distress syndrome (ARDS) patients. Therefore, the present study explores the effect of pravastatin with and without additional moderate acute hypercapnia on intestinal microvascular oxygenation and blood flow in experimental sepsis.

METHODS

Forty male Wistar rats were randomized into four groups. Half of the animals received 0.2 mg • kg pravastatin s.c., the other half received the same volume as vehicle (NaCl 0.9%). After 18 h, colon ascendens stent peritonitis surgery was conducted in all animals to induce sepsis. Twenty-four hours after surgery, baseline was established and the animals were subjected to either 120 min of normocapnic (pCO2 40 ± 6 mm Hg) or moderate hypercapnic (pCO2 72 ± 10 mm Hg) ventilation. Microcirculatory oxygenation (μHBO2) and perfusion (μflow) of the colon were continuously recorded using tissue reflectance spectrophotometry and laser Doppler, respectively.

RESULTS

In normocapnic septic animals μHBO2 decreased over time (-8.4 ± 8.7%; P < 0.05 vs. baseline), whereas after pravastatin pretreatment μHBO2 remained constant (-1.9 ± 5.7% vs. baseline). However, in hypercapnic septic animals pretreated with pravastatin μHBO2 declined significantly over time (-8.9 ± 11.8%; P < 0.05 vs. baseline) and was significantly lower compared with normocapnic pravastatin-pretreated animals. μflow did not change over time in any group.

CONCLUSION

Pravastatin pretreatment ameliorates the intestinal microvascular oxygenation in sepsis and thus seems to prevent intestinal hypoxia. Furthermore, we demonstrated that additional hypercapnia abolishes this effect, indicating why septic ARDS patients might not benefit from pravastatin therapy.

An EAPCI Expert Consensus Document on Ischaemia with Non-Obstructive Coronary Arteries in Collaboration with European Society of Cardiology Working Group on Coronary Pathophysiology & Microcirculation Endorsed by Coronary Vasomotor Disorders International Study Group

This consensus document, a summary of the views of an expert panel organized by the European Association of Percutaneous Cardiovascular Interventions (EAPCI), appraises the importance of ischaemia with non-obstructive coronary arteries (INOCA). Angina pectoris affects approximately 112 million people globally. Up to 70% of patients undergoing invasive angiography do not have obstructive coronary artery disease, more common in women than in men, and a large proportion have INOCA as a cause of their symptoms. INOCA patients present with a wide spectrum of symptoms and signs that are often misdiagnosed as non-cardiac leading to under-diagnosis/investigation and under-treatment. INOCA can result from heterogeneous mechanism including coronary vasospasm and microvascular dysfunction and is not a benign condition. Compared to asymptomatic individuals, INOCA is associated with increased incidence of cardiovascular events, repeated hospital admissions, as well as impaired quality of life and associated increased health care costs. This consensus document provides a definition of INOCA and guidance to the community on the diagnostic approach and management of INOCA based on existing evidence from research and best available clinical practice; noting gaps in knowledge and potential areas for further investigation.

[Chronic coronary syndrome : New classification of stable coronary artery disease]

In 2019 the European Society for Cardiology (ESC) published guidelines for the diagnosis and management of chronic coronary syndromes (CCS). Thus the term "stable coronary artery disease" is replaced by CCS. The newly introduced term is based on the current understanding of pathogenesis and clinical features of coronary artery disease (CAD) as well as therapeutic management. CCS defines CAD as a chronic process that can be influenced by lifestyle adjustments, pharmacological therapies and invasive interventions (percutaneous coronary intervention, coronary artery bypass grafting) with the aim of stabilization or regression. The present work provides an overview of various scenarios that involve CCS and diagnostic pathways to clarify potentially relevant CAD. It also highlights therapeutic management and secondary preventive procedures in accordance with the current recommendations of the ESC.

Effects of Oral Drugs on Coronary Microvascular Function in Patients Without Significant Stenosis of Epicardial Coronary Arteries: A Systematic Review and Meta-Analysis of Coronary Flow Reserve

Objective: This study aims to investigate the impact of cardiovascular medications on the coronary flow reserve (CFR) in patients without obstructive coronary artery disease (CAD).

Methods: We searched PubMed, EMBASE, and Cochrane databases from inception to 15 November 2019. Studies were included if they reported CFR from baseline to follow-up after oral drug therapy of patients without obstructive CAD. Data was pooled using random-effects modeling. The primary outcome was change in CFR from baseline to follow-up after oral drug therapy.

Results: A total of 46 studies including 845 subjects were included in this study. Relative to baseline, the CFR was improved by angiotensin-converting enzymes (ACEIs), aldosterone receptor antagonists (ARBs) [standard mean difference (SMD): 1.12; 95% CI: 0.77–1.47], and statins treatments (SMD: 0.61; 95%CI: 0.36–0.85). Six to 12 months of calcium channel blocker (CCB) treatments improved CFR (SMD: 1.04; 95% CI: 0.51–1.58). Beta-blocker (SMD: 0.24; 95% CI: −0.39–0.88) and ranolazine treatment (SMD: 0.31; 95% CI: −0.39–1.01) were not associated with improved CFR.

Conclusions: Therapy with ACEIs, ARBs, and statins was associated with improved CFR in patients with confirmed or suspicious CMD. CCBs also improved CFR among patients followed for 6–12 months. Beta-blocker and ranolazine had no impact on CFR.

Assessment of Vascular Dysfunction in Patients Without Obstructive Coronary Artery Disease: Why, How, and When

Ischemic heart disease secondary to coronary vascular dysfunction causes angina and impairs quality of life and prognosis. About one-half of patients with symptoms and signs of ischemia turn out not to have obstructive coronary artery disease, and coronary vascular dysfunction may be relevant. Adjunctive tests of coronary vasomotion include guidewire-based techniques with adenosine and reactivity testing, typically by intracoronary infusion of acetylcholine. The CorMicA (Coronary Microvascular Angina) trial provided evidence that routine management guided by an interventional diagnostic procedure and stratified therapy improves angina and quality of life in patients with angina but no obstructive coronary artery disease. In this paper, the COVADIS study group provide a comprehensive review of why, how, and when coronary vascular dysfunction should be assessed invasively. They discuss the rationale through a shared understanding of vascular pathophysiology and clinical evidence. They propose a consensus approach to how an interventional diagnostic procedure is performed with focus on practical aspects. Finally, the authors discuss the clinical scenarios in patients with stable and acute coronary syndromes in which measurement of coronary vascular function may be helpful for patient care.

Ischaemia with no obstructive coronary arteries

Ischaemia with no obstructive coronary arteries (INOCA) is a common ischaemic heart disease with a female preponderance, mostly due to underlying coronary vascular dysfunction comprising coronary microvascular dysfunction and/or epicardial coronary vasospasm. Since standard ischaemia detection tests and coronary angiograms are not suitable to diagnose coronary vascular dysfunction, INOCA is often overlooked in current cardiology practice. Future research, including large outcome trials, is much awaited. Yet, adequate diagnosis is possible and treatment options are available and vital to reduce symptoms and most probably improve cardiovascular prognosis. This review intends to give a brief overview of the clinical presentation, underlying pathophysiology, and the diagnostic and treatment options in patients with suspected INOCA.

Different vasoreactivity of arterial bypass grafts versus native coronary arteries in response to acetylcholine

BACKGROUND

Coronary angiography is often performed in patients with recurrent angina after successful coronary artery bypass grafting (CABG) in search of the progression of atherosclerosis. However, in many of these patients, no relevant stenosis can be detected. We speculate that coronary spasm may be associated with angina in these patients.

METHODS

From 2307 patients with unobstructed coronaries who underwent intracoronary acetylcholine spasm provocation testing (ACh-test) between 2012 and 2016, 54 consecutive patients who fulfilled the following inclusion criteria were included in this cohort study: previous left internal thoracic artery (LITA) bypass on the left anterior descending (LAD) coronary artery, ongoing/recurrent angina pectoris, no significant (< 50%) coronary artery or bypass stenosis. In all participants, the ACh-test was performed via the LITA bypass.

RESULTS

In 14 patients (26%) the ACh-test elicited epicardial spasm of the LAD distal to the anastomosis (≥ 90% diameter reduction with reproduction of the patient's symptoms and ischemic ECG shifts). Microvascular spasm (reproduction of symptoms and ischemic ECG-changes but no epicardial spasm) was seen in 30 patients (55%). The ACh-test was normal in the remaining 10 patients (19%). ACh-testing did not elicit any relevant vasoconstriction in the LITA bypasses in contrast to the LAD on quantitative coronary analyses (4.89 ± 7.36% vs. 52.43 ± 36.07%, p < 0.01).

CONCLUSION

Epicardial and microvascular coronary artery spasm are frequent findings in patients with ongoing or recurrent angina after CABG but no relevant stenosis. Vasoreactivity to acetylcholine is markedly different between LITA bypasses and native LAD arteries with vasoconstriction almost exclusively occurring in the LAD.

Clinical characteristics and biomarkers of coronary microvascular dysfunction and obstructive coronary artery disease

Objective

The purpose of this study was to determine the clinical characteristics and biomarkers in patients with coronary microvascular dysfunction (CMVD) and to compare them with patients with obstructive coronary artery disease (OCAD).

Methods

We conducted a single-center, hospital-based, observational, descriptive, comparative, clinical study of 40 patients, including 20 patients with CMVD and 20 with OCAD. We assessed laboratory biomarkers (low-density lipoprotein [LDL], high-density lipoprotein [HDL], red blood cell distribution width [RDW], brain natriuretic protein [BNP], troponin I), and PET/CT coronary flow reserve was performed.

Results

The mean coronary flow reserve (CFR) in patients with CMVD was 1.96±0.55. Mean low-density lipoprotein cholesterol (LDL-C) levels were significantly higher in the CMVD subgroup (2.53±0.63 mmol/L) compared with the OCAD subgroup (1.76±0.97 mmol/L). Logistic regression analysis identified LDL-C as a predictor for the development of CMVD (odds ratio, 5.24).

Conclusion

It is difficult to differentiate between OCAD and CMVD based on the patient’s medical history, clinical characteristics, and coronary angiography results. Further investigations may be needed to allow an accurate diagnosis. CFR measurements based on non-invasive positron emission tomography/computed tomography may aid the diagnosis of CMVD. We also identified LDL-C as a predictor for the development of CMVD.

1-Year Outcomes of Angina Management Guided by Invasive Coronary Function Testing (CorMicA)

Objectives

The aim of this study was to test the hypothesis that invasive coronary function testing at time of angiography could help stratify management of angina patients without obstructive coronary artery disease.

Background

Medical therapy for angina guided by invasive coronary vascular function testing holds promise, but the longer-term effects on quality of life and clinical events are unknown among patients without obstructive disease.

Methods

A total of 151 patients with angina with symptoms and/or signs of ischemia and no obstructive coronary artery disease were randomized to stratified medical therapy guided by an interventional diagnostic procedure versus standard care (control group with blinded interventional diagnostic procedure results). The interventional diagnostic procedure–facilitated diagnosis (microvascular angina, vasospastic angina, both, or neither) was linked to guideline-based management. Pre-specified endpoints included 1-year patient-reported outcome measures (Seattle Angina Questionnaire, quality of life [EQ-5D]) and major adverse cardiac events (all-cause mortality, myocardial infarction, unstable angina hospitalization or revascularization, heart failure hospitalization, and cerebrovascular event) at subsequent follow-up.

Results

Between November 2016 and December 2017, 151 patients with ischemia and no obstructive coronary artery disease were randomized (n = 75 to the intervention group, n = 76 to the control group). At 1 year, overall angina (Seattle Angina Questionnaire summary score) improved in the intervention group by 27% (difference 13.6 units; 95% confidence interval: 7.3 to 19.9; p < 0.001). Quality of life (EQ-5D index) improved in the intervention group relative to the control group (mean difference 0.11 units [18%]; 95% confidence interval: 0.03 to 0.19; p = 0.010). After a median follow-up duration of 19 months (interquartile range: 16 to 22 months), major adverse cardiac events were similar between the groups, occurring in 9 subjects (12%) in the intervention group and 8 (11%) in the control group (p = 0.803).

Conclusions

Stratified medical therapy in patients with ischemia and no obstructive coronary artery disease leads to marked and sustained angina improvement and better quality of life at 1 year following invasive coronary angiography. (Coronary Microvascular Angina [CorMicA]; NCT03193294)

Diagnosis of patients with angina and non-obstructive coronary disease in the catheter laboratory

Around 40% of all patients undergoing angiography are found to have normal coronary arteries or non-obstructive coronary artery disease (NOCAD). Despite the high prevalence, this is a group who rarely receive a definitive diagnosis, are frequently labelled and managed inappropriately and by and large, continue to remain symptomatic. Half of this group will have coronary microvascular dysfunction (CMD), associated with a higher rate of major adverse cardiovascular events; identifying CMD represents a therapeutic target of unmet need. As the pressure wire has revolutionised our ability to interrogate epicardial coronary disease during the time of angiography, measuring flow can similarly classify NOCAD during a single procedure. Assessment of flow is a function that is already integral to some pressure wires and furthermore, the familiarity and usage of the combined Doppler and pressure wire is rapidly increasing-these are techniques that readily lend themselves to the skillset of a practising interventional cardiologist. We present a structured algorithm designed for cardiologists who frequently encounter NOCAD in the catheter laboratory, identifying specific disease phenotypes within this heterogeneous population with linked therapy. This review paper clearly explains the rationale for this algorithm and outlines its applicability to routine clinical practice and also, the importance of phenotyping for future research. Ultimately, personalised therapy could improve outcomes for both patients and healthcare providers; while these approaches in turn will need robust evaluation to ensure that they improve both clinical outcomes and health economic benefits, this proposal will provide a framework for future trials and evaluations.

Biopsy-confirmed endothelial cell activation in patients with coronary microvascular dysfunction

BACKGROUND

Patients with angina yet having unobstructed coronaries are found in ∼50% of cases undergoing invasive angiography. Coronary spasm and microvascular dysfunction can be responsible for the clinical presentation in ∼60% of cases. However, little is known about structural changes in the myocardium. The aim of this study was to describe findings in endomyocardial biopsies of symptomatic patients with unobstructed coronaries.

PATIENTS AND METHODS

We retrospectively analyzed a cohort of 1416 consecutive patients who underwent endomyocardial biopsy sampling and coronary angiography between 2002 and 2016 for various clinical indications. Of them, 309 patients had also undergone intracoronary acetylcholine testing (ACH-test). To be eligible for the study, patients had to have normal left ventricular ejection fraction, unobstructed coronaries and absence of viral genomes in the myocardium.

RESULTS

Among the final cohort of 33 (70% female, mean age 53) patients, the ACH-test revealed coronary microvascular spasm in 11 (33.3%) patients. Twelve (36.4%) patients had epicardial spasm and 10 (30.3%) had an uneventful ACH-test. Immunohistology revealed activated macrophages in 10 (30%) cases and activated endothelial cells as well as perivascular or interstitial fibrosis in 17 (52%). Myocardial hypertrophy was seen in nine (27%) patients, and smooth muscle cell proliferation was present in 11 (33%) cases. Compared with the rest of the cohort, patients with microvascular spasm significantly more often had activated endothelial cells (P=0.003).

CONCLUSION

This study gives unique insights into structural myocardial alterations in patients with angina, unobstructed coronaries and abnormal coronary vasomotion, suggesting that a combination of both structural and functional alterations is frequent.

Coronary microvascular dysfunction is associated with poor glycemic control amongst female diabetics with chest pain and non-obstructive coronary artery disease

Background

Patients with type 2 diabetes mellitus are at an increased risk of adverse cardiovascular events compared to those without diabetes. The timing, relative to disease onset, and degree of glycemic control that reduces the risk of adverse cardiovascular events remains uncertain. Coronary microvascular dysfunction is prevalent in patients with type 2 diabetes mellitus and is linked to adverse cardiovascular events. We assessed the association between endothelial-dependent and endothelial-independent coronary microvascular dysfunction and glycemic control in patients presenting with chest pain and nonobstructive coronary disease at angiography.

Methods

Patients presenting with chest pain and found to have non-obstructive CAD (stenosis < 40%) at angiography underwent an invasive assessment of endothelial-independent and endothelial –dependent microvascular function. Endothelial-independent microvascular function was assessed by comparing the coronary flow velocity, measured using a Doppler guidewire, in response to intracoronary infusion of adenosine to calculate the coronary flow reserve ratio in response to adenosine (CFRAdn Ratio). A CFRAdn Ratio ≤ 2.5 was considered abnormal. Endothelial-dependent microvascular function was assessed by measuring the percent change in coronary blood flow in response to intracoronary infusions of acetylcholine (%ΔCBFAch), and microvascular endothelial dysfunction defined as a %ΔCBFAch of ≤ 50%. Patients were classified by normal versus abnormal CFRAdn Ratio and %ΔCBFAch. Measurements of HbA1c and fasting serum glucose were obtained prior to catheterization and compared between groups.

Results

Between 1993 and 2012, 1469 patients (mean age 50.4 years, 35% male) underwent coronary angiography and invasive testing for coronary microvascular dysfunction, of which 129 (8.8%) had type 2 diabetes. Fifty-one (39.5%) had an abnormal %ΔCBFAch and 49 (38.0%) had an abnormal CFRAdn Ratio. Conventional cardiovascular risk factors and cardiovascular or diabetic medication use did not vary significantly between groups. Females with an abnormal CFRAdn Ratio or abnormal %ΔCBFAch had a significantly higher HbA1c compared to patients with a normal CFRAdn Ratio or %ΔCBFAch respectively: HbA1c % (standard deviation) 7.4 (2.1) vs. 6.5 (1.1), p = 0.035 and 7.3 (1.9) vs. 6.4 (1.2), p = 0.022, respectively. Female patients with an abnormal CFRAdn Ratio had significantly higher fasting serum glucose concentrations compared to those with a normal CFRAdn Ratio: fasting serum glucose mg/dL (standard deviation) 144.4 (55.6) vs. 121.9 (28.1), p = 0.035. This was not observed in men. Amongst female diabetics, a higher HbA1c was significantly associated with any coronary microvascular dysfunction both in a univariate and multivariate analysis: odds ratio (95% confidence interval) 1.69 (1.01–2.86) p = 0.049; and a fasting serum glucose > 140 mg/dL was significantly associated with an abnormal CFRAdn Ratio, 4.28 (1.43–12.81).

Conclusion

Poor glycemic control is associated with coronary microvascular dysfunction amongst female diabetics presenting with chest pain and non-obstructive CAD. These findings highlight the importance of sex specific risk stratification models and treatment strategies when managing cardiovascular risk amongst diabetics. Further studies are required to identify additional risk prevention tools and therapies targeting microvascular dysfunction as an integrated index of cardiovascular risk.

Electronic supplementary material

The online version of this article (10.1186/s12933-019-0833-1) contains supplementary material, which is available to authorized users.

Stratified Medical Therapy Using Invasive Coronary Function Testing in Angina: The CorMicA Trial

BACKGROUND

Patients with angina symptoms and/or signs of ischemia but no obstructive coronary artery disease (INOCA) pose a diagnostic and therapeutic challenge.

OBJECTIVES

The purpose of this study was to test whether an interventional diagnostic procedure (IDP) linked to stratified medicine improves health status in patients with INOCA.

METHODS

The authors conducted a randomized, controlled, blinded clinical trial of stratified medical therapy versus standard care in patients with angina. Patients with angina undergoing invasive coronary angiography (standard care) were recruited. Patients without obstructive CAD were immediately randomized 1:1 to the intervention group (stratified medical therapy) or the control group (standard care, IDP sham procedure). The IDP consisted of guidewire-based assessment of coronary flow reserve, index of microcirculatory resistance, fractional flow reserve, followed by vasoreactivity testing with acetylcholine. The primary endpoint was the mean difference in angina severity at 6 months (assessed by the Seattle Angina Questionnaire summary score).

RESULTS

A total of 391 patients were enrolled between November 25, 2016, and November 12, 2017. Coronary angiography revealed obstructive disease in 206 (53.7%). One hundred fifty-one (39%) patients without angiographically obstructive CAD were randomized (n = 76 intervention group; n = 75 blinded control group). The intervention resulted in a mean improvement of 11.7 U in the Seattle Angina Questionnaire summary score at 6 months (95% confidence interval [CI]: 5.0 to 18.4; p = 0.001). In addition, the intervention led to improvements in the mean quality-of-life score (EQ-5D index 0.10 U; 95% CI: 0.01 to 0.18; p = 0.024) and visual analogue score (14.5 U; 95% CI: 7.8 to 21.3; p < 0.001). There were no differences in major adverse cardiac events at the 6-month follow-up (2.6% controls vs. 2.6% intervention; p = 1.00).

CONCLUSIONS

Coronary angiography often fails to identify patients with vasospastic and/or microvascular angina. Stratified medical therapy, including an IDP with linked medical therapy, is routinely feasible and improves angina in patients with no obstructive CAD. (CORonary MICrovascular Angina [CorMicA]; NCT03193294).

Identifying Myocardial Ischemia due to Coronary Microvascular Dysfunction in the Emergency Department: Introducing a New Paradigm in Acute Chest Pain Evaluation

Chest pain stands as one of the most frequent patient presentations in the emergency department (ED). Despite established diagnostic algorithms for identifying several important causes of chest pain, such as acute myocardial infarction (AMI), aortic dissection, and pulmonary embolism, guidance on managing patients with recurrent chest pain, one of the top 3 reasons for repeated hospitalization in the United States, is less defined. The assessment of symptoms, serial ECG, and necrosis biomarkers plays a major role in patient management. Notably, the recently introduced high-sensitivity troponin T (hs-TnT) assay is helping to identify ischemia in patients previously undiagnosed by conventional testing. In Europe, with the use of this assay for over a decade, the identification of patients with AMI has substantially increased, particularly of patients with type 2 AMI, which is seen in the absence of atherosclerotic obstruction of the epicardial coronaries on angiography. Use of hs-TnT is in particular relevant in women, in whom the use of a sex-specific threshold for elevated hs-TnT has almost doubled the diagnosis of AMI. With the advent of the hs-TnT assay in the United States in 2017, a similar phenomenon is expected. Thus, it is important to learn from the European experience and to develop sex-specific nuanced algorithms for the evaluation of additional causes of myocardial ischemia/necrosis, such as coronary artery vasomotor disorders and coronary microvascular dysfunction. The latter has a high prevalence among symptomatic women presenting to the ED, a group in whom recurrent chest pain is common. This commentary describes the tools available for diagnosing epicardial- and non-epicardial-related myocardial ischemia in patients with recurrent chest pain in the ED setting. A sex-specific, nuanced approach applied to select groups of patients being observed in the ED has the potential to reduce admissions and to allow for the initiation of timely, appropriate medical treatment and outpatient follow-up in an at-risk population. The costs and availability of advanced diagnostics may pose some limitation to the widespread adoption of such protocols.

[MINOCA-myocardial infarction with non-obstructive coronary arteries]

In recent years it has been observed with increasing interest that there is a group of patients with electrocardiographic and laboratory features of myocardial infarction (MI) but no obstructive coronary artery disease (<50% diameter stenosis). For this entity the term myocardial infarction with non-obstructive coronary arteries (MINOCA) has been coined. The prevalence of MINOCA is estimated to be 6-9% among patients diagnosed with MI and it is more common in women than men as well as in patients presenting with NSTEMI than in those presenting with STEMI. The MINOCA is a working diagnosis that requires a further diagnostic work-up by invasive techniques, such as intravascular ultrasound (IVUS) and optical coherence tomography (OCT) or non-invasive imaging with cardiac magnetic resonance imaging (CMRI). When it is ascertained that obstructive coronary artery disease has not been inadvertently overlooked, other coronary disorders, such as plaque rupture or erosion, thrombosis, dissection, spasms or microvascular dysfunction should be evaluated. Furthermore, myocarditis or tako-tsubo cardiomyopathy should be excluded by CMRI as non-coronary causes. The further treatment and prognosis of patients with MINOCA depend on the underlying cause and the final diagnosis.

Invasive Assessment of the Coronary Microvasculature

Traditionally, invasive coronary physiological assessment has focused on the epicardial coronary artery. More recently, appreciation of the importance of the coronary microvasculature in determining patient outcomes has grown. Several invasive modalities for interrogating microvascular function have been proposed. Angiographic techniques have been limited by their qualitative and subjective nature. Doppler wire-derived coronary flow reserve has been applied in research studies, but its clinical role has been limited by its lack of reproducibility, its lack of a clear normal value, and the fact that it is not specific for the microvasculature but interrogates the entire coronary circulation. The index of microcirculatory resistance—a thermodilution-derived measure of the minimum achievable microvascular resistance—is relatively easy to measure, more reproducible, has a clearer normal value, and is independent of epicardial coronary artery stenosis. The index of microcirculatory resistance has been shown to have prognostic value in patients with ST-segment–elevation myocardial infarction and cardiac allograft vasculopathy after heart transplantation. Emerging data demonstrate its role in evaluating patients with chest pain and nonobstructive coronary artery disease. Increasingly, the index of microcirculatory resistance is used as a reference standard for invasively assessing the microvasculature in clinical trials.