Primary Coronary Microvascular Dysfunction

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.

The Role of IL-6 and ET-1 in the Diagnosis of Coronary MicroVascular Disease in Women

BACKGROUND

Microvascular angina is a common clinical entity, with about a three-fold higher frequency in women. The pathogenesis of microvascular angina has not been much studied, but inflammation and endothelial dysfunction have been incriminated as the main mechanisms of this disease. Methoss: Our purpose was to analyze whether certain inflammatory markers, i.e., interleukin 6 (IL-6) and endothelin 1 (ET-1), can play a role in the diagnosis of microvascular angina in women.

RESULTS

Ninety women with ischemic heart disease were divided into two groups, based on their affliction with either microvascular or macrovascular disease. In general, the levels of IL6 and ET1 were similar between the two groups. Analyzing these marker levels according to the number of coronary lesions, we obtained an increased IL6 value that was similar for patients with microvascular angina, one-vessel, and two-vessel coronary disease, but significantly lower than in women with three-vessel coronary lesions. Also, in microvascular angina, IL6 level was correlated with the NYHA IV functional class. Unexpectedly, the level of ET1 was correlated with left ventricular systolic dysfunction.

CONCLUSIONS

In women with an increased suspicion of microvascular angina, in whom microvascular dysfunction cannot be tested invasively, IL-6 level, unlike the ET-1 level, might be considered a diagnostic marker of this disease.

Diagnostic approach for coronary microvascular dysfunction in patients with chest pain and no obstructive coronary artery disease

A large number of studies has demonstrated that abnormalities of coronary microcirculation may be responsible for both acute and chronic cardiac ischemic syndromes. In clinical practice the microvascular origin of myocardial ischemia and angina is usually considered in patients who are found to have normal or near-normal coronary arteries at angiography. In this article, we review the diagnostic approach to patients with suspected coronary microvascular dysfunction as a cause of ischemic syndromes and also suggest a classification of chronic and acute microvascular coronary ischemic syndrome, including myocardial infarction with normal coronary arteries.

Assessment and pathophysiology of microvascular disease: recent progress and clinical implications

The development of novel, non-invasive techniques and standardization of protocols to assess microvascular dysfunction have elucidated the key role of microvascular changes in the evolution of cardiovascular (CV) damage, and their capacity to predict an increased risk of adverse events. These technical advances parallel with the development of novel biological assays that enabled the ex vivo identification of pathways promoting microvascular dysfunction, providing novel potential treatment targets for preventing cerebral-CV disease. In this article, we provide an update of diagnostic testing strategies to detect and characterize microvascular dysfunction and suggestions on how to standardize and maximize the information obtained from each microvascular assay. We examine emerging data highlighting the significance of microvascular dysfunction in the development CV disease manifestations. Finally, we summarize the pathophysiology of microvascular dysfunction emphasizing the role of oxidative stress and its regulation by epigenetic mechanisms, which might represent potential targets for novel interventions beyond conventional approaches, representing a new frontier in CV disease reduction.

Pharmacological and simulated exercise cardiac stress tests produce different ischemic signatures in high-resolution experimental mapping studies

OBJECTIVE

Test the hypothesis that exercise and pharmacological cardiac stressors create different electrical ischemic signatures.

INTRODUCTION

Current clinical stress tests for detecting ischemia lack sensitivity and specificity. One unexplored source of the poor detection is whether pharmacological stimulation and regulated exercise produce identical cardiac stress.

METHODS

We used a porcine model of acute myocardial ischemia in which animals were instrumented with transmural plunge-needle electrodes, an epicardial sock array, and torso arrays to simultaneously measure cardiac electrical signals within the heart wall, the epicardial surface, and the torso surface, respectively. Ischemic stress via simulated exercise and pharmacological stimulation were created with rapid electrical pacing and dobutamine infusion, respectively, and mimicked clinical stress tests of five 3-minute stages. Perfusion to the myocardium was regulated by a hydraulic occluder around the left anterior descending coronary artery. Ischemia was measured as deflections to the ST-segment on ECGs and electrograms.

RESULTS

Across eight experiments with 30 (14 simulated exercise and 16 dobutamine) ischemic interventions, the spatial correlations between exercise and pharmacological stress diverged at stage three or four during interventions (p<0.05). We found more detectable ST-segment changes on the epicardial surface during simulated exercise than with dobutamine (p<0.05). The intramyocardial ischemia formed during simulated exercise had larger ST40 potential gradient magnitudes (p<0.05).

CONCLUSION

We found significant differences on the epicardium between cardiac stress types using our experimental model, which became more pronounced at the end stages of each test. A possible mechanism for these differences was the larger ST40 potential gradient magnitudes within the myocardium during exercise. The presence of microvascular dysfunction during exercise and its absence during dobutamine stress may explain these differences.

The Lancet women and cardiovascular disease Commission: reducing the global burden by 2030

Cardiovascular disease is the leading cause of death in women. Decades of grassroots campaigns have helped to raise awareness about the impact of cardiovascular disease in women, and positive changes affecting women and their health have gained momentum. Despite these efforts, there has been stagnation in the overall reduction of cardiovascular disease burden for women in the past decade. Cardiovascular disease in women remains understudied, under-recognised, underdiagnosed, and undertreated. This Commission summarises existing evidence and identifies knowledge gaps in research, prevention, treatment, and access to care for women. Recommendations from an international team of experts and leaders in the field have been generated with a clear focus to reduce the global burden of cardiovascular disease in women by 2030. This Commission represents the first effort of its kind to connect stakeholders, to ignite global awareness of sex-related and gender-related disparities in cardiovascular disease, and to provide a springboard for future research.

Predicting Long-Term Mortality in Patients with Angina across the Spectrum of Dysglycemia: A Machine Learning Approach

We aimed to develop and validate a model for predicting mortality in patients with angina across the spectrum of dysglycemia. A total of 1479 patients admitted for coronary angiography due to angina were enrolled. All-cause mortality served as the primary endpoint. The models were validated with five-fold cross validation to predict long-term mortality. The features selected by least absolute shrinkage and selection operator (LASSO) were age, heart rate, plasma glucose levels at 30 min and 120 min during an oral glucose tolerance test (OGTT), the use of angiotensin II receptor blockers, the use of diuretics, and smoking history. This best performing model was built using a random survival forest with selected features. It had a good discriminative ability (Harrell’s C-index: 0.829) and acceptable calibration (Brier score: 0.08) for predicting long-term mortality. Among patients with obstructive coronary artery disease confirmed by angiography, our model outperformed the Global Registry of Acute Coronary Events discharge score for mortality prediction (Harrell’s C-index: 0.829 vs. 0.739, p < 0.001). In conclusion, we developed a machine learning model to predict long-term mortality among patients with angina. With the integration of OGTT, the model could help to identify a high risk of mortality across the spectrum of dysglycemia.

Potential Role of Cardiopulmonary Exercise Testing as an Early Screening Tool for Patients With Suspected Pulmonary Hypertension Including Exercise-Induced Pulmonary Hypertension: Results From a Retrospective Analysis

OBJECTIVE

The primary goal of our retrospective case-control study was to evaluate the ability of cardiopulmonary exercise testing to screen for underlying exercise-induced pulmonary hypertension (EIPH) in symptomatic patients who had a negative stress test and elevated right ventricular systolic pressure on echocardiogram. We also evaluated long-acting nitrates and ranolazine as medication challenges.

SETTING

Performed at a single, tertiary-care medical center in the United States.

PARTICIPANTS

Based on the inclusion and exclusion criteria, 81 patients were included in this study. The primary outcome of the study was to measure mean pulmonary arterial pressure at rest and exertion, as well as Wasserman curves. We also recorded patient demographics and risk factors, left ventricular ejection fraction, and mean oxygen consumption. Additionally, patients were monitored symptomatically after receiving long-acting nitrates and ranolazine.

RESULTS

A total of 61 patients had resting pulmonary arterial hypertension, and 27 had EIPH. The EIPH group had a significantly higher mean age of 71.67 years. Wasserman curves calculated from the cardiopulmonary exercise testing data revealed 3 subgroups of EIPH patients: cardiac restriction, chronotropic incompetence, and combination of both patterns. The EIPH group showed significant improvement in symptoms after receiving long-acting nitrate therapy.

CONCLUSIONS

Many patients with symptoms of angina, dyspnea, and/or fatigue on exertion with negative cardiac stress testing may have underlying pulmonary arterial hypertension, including EIPH. Therefore, these patients require adequate treatment and follow-up to prevent worsening of symptoms and pathology.

Human coronary inflammation by computed tomography: Relationship with coronary microvascular dysfunction

Background A new imaging metric using coronary computed tomography angiography (CCTA), addressing the peri-coronary adipose tissue (PCAT) computed tomography (CT) attenuation, has been clinically validated. This method provides information regarding coronary inflammation. It is unclear how coronary inflammation affects microvascular function. The non-invasive evaluation of coronary flow velocity reserve is widely used in clinical practice using Doppler measurement on the left anterior descending coronary artery (CFVR-lad) during stress-echocardiography (SE). We hypothesize that coronary inflammation affects CFVR-lad and, in the absence of overt CAD, they are significantly correlated. Methods We evaluated the relationship between coronary inflammation (by PCAT CT attenuation) and coronary microvascular function (by CFVR-lad) in subjects with no or non-obstructive (diameter stenosis <70%) coronary artery disease (CAD). Results Two-hundred and two subjects were enrolled in the study. The relationship between PCAT CT attenuation and CFVR-lad show a significant inverse relationship in the entire group of subjects enrolled in the study (r = -0.32, p < 0.001). Correlation between PCAT CT attenuation and CFVR-lad was significant in subjects with no or mild CAD-lad, while this was not the case in subjects with intermediate CAD-lad. The R and R² were respectively -0.40, -0.16 in subjects without CAD (p < 0.001) and - 0.35 and - 0.12 in subjects with mild CAD-lad (p = 0.001). Conclusions The main finding of the current study is the independent relationship between coronary microvascular function, by Doppler CFVR-lad during SE, in subjects without severely obstructive CAD in the left anterior descending coronary artery, and the level of local coronary inflammation, by PCAT attenuation measurement on CCTA.

Management of refractory angina: an update

Despite the use of anti-anginal drugs and/or percutaneous coronary interventions (PCI) or coronary artery bypass grafting, the proportion of patients with coronary artery disease who have daily or weekly angina ranges from 2% to 24%. Refractory angina refers to long-lasting symptoms (for >3 months) due to established reversible ischaemia, which cannot be controlled by escalating medical therapy with the use of 2nd- and 3rd-line pharmacological agents, bypass grafting, or stenting. While there is uncertain prognostic benefit, the treatment of refractory angina is important to improve the quality of life of the patients affected. This review focuses on conventional pharmacological approaches to treating refractory angina, including guideline directed drug combination and dosages. The symptomatic and prognostic impact of advanced and novel revascularization strategies such as chronic total occlusion PCI, transmyocardial laser revascularization, coronary sinus occlusion, radiation therapy for recurrent restenosis, and spinal cord stimulation are also covered and recommendations of the 2019 ESC Guidelines on the Diagnosis and Management of Chronic Coronary Syndromes discussed. Finally, the potential clinical use of current angiogenetic and stem cell therapies in reducing ischaemia and/or pain is evaluated.

Doctor, I feel microvascular chest pain

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Modeling Left Ventricle Perfusion in Healthy and Stenotic Conditions

A theoretical fluid mechanical model is proposed for the investigation of myocardial perfusion in healthy and stenotic conditions. The model hinges on Terzaghi’s consolidation theory and reformulates the related unsteady flow equation for the simulation of the swelling–drainage alternation characterizing the diastolic–systolic phases. When compared with the outcome of experimental in vivo observations in terms of left ventricle transmural perfusion ratio (T.P.R.), the analytical solution provided by the present study for the time-dependent blood pressure and flow rate across the ventricle wall proves to consistently reproduce the basic mechanisms of both healthy and ischemic perfusion. Therefore, it could constitute a useful interpretative support to improve the comprehension of the basic hemodynamic mechanisms leading to the most common cardiac diseases. Additionally, it could represent the mathematical basis for the application of inverse methods aimed at estimating the characteristic parameters of ischemic perfusion (i.e., location and severity of coronary stenoses) via downstream ventricular measurements, possibly inspiring their assessment via non-invasive myocardial imaging techniques.

Postexercise troponin I levels in patients with suspected stable ischemic heart disease

BACKGROUND AND AIMS

Previous studies showed that troponin blood levels may increase after exercise. In this study, we assessed whether, among patients with suspected of having stable angina, the increase in troponin I (TnI) levels after exercise stress test (EST) might help identify those with obstructive coronary artery disease (CAD) and myocardial ischemia.

METHODS

We performed maximal treadmill EST in 50 patients (age 64 ± 9 years; 38 men) admitted to our Cardiology Department to undergo elective coronary angiography because of a suspicion of stable angina. TnI was measured before and 12 h after EST.

RESULTS

TnI increased after EST compared with baseline in the whole population (from 0.44 ± 0.76 to 0.84 ± 1.12 ng/dl, P < 0.001). No difference in TnI increase was observed between patients with obstructive CAD (n = 29; 0.61 ± 0.90-1.13 ± 1.33 ng/dl) and no obstructive CAD (NO-CAD; n = 21; 0.21 ± 0.46-0.44 ± 0.54 ng/dl; P = 0.51). There was also no significant difference in post-EST TnI increase between patients with positive EST (n = 34; 0.56 ± 0.89-1.05 ± 1.28 ng/dl) or negative EST (n = 16; 0.19 ± 0.26-0.39 ± 0.43 ng/dl; P = 0.16). Moreover, no significant difference was observed in the post-EST TnI increase among groups of patients with positive EST and obstructive CAD, positive EST and NO-CAD, negative EST and obstructive CAD and negative EST and NO-CAD (P = 0.12). No clinical or EST variable was associated with post-EST TnI increase, although there was a tendency for a greater increase in those achieving a heart rate more than 85 vs. less than 85% of maximal predicted heart rate during EST (P = 0.075).

CONCLUSION

TnI increase after EST in patients with suspected stable angina is largely independent of the results of coronary angiography and EST.

Non-randomized comparison between revascularization and deferral for intermediate coronary stenosis with abnormal fractional flow reserve and preserved coronary flow reserve

Limited data are available regarding comparative prognosis after percutaneous coronary intervention (PCI) versus deferral of revascularization in patients with intermediate stenosis with abnormal fractional flow reserve (FFR) but preserved coronary flow reserve (CFR). From the International Collaboration of Comprehensive Physiologic Assessment Registry (NCT03690713), a total of 330 patients (338 vessels) who had coronary stenosis with FFR ≤ 0.80 but CFR > 2.0 were selected for the current analysis. Patient-level clinical outcome was assessed by major adverse cardiac events (MACE) at 5 years, a composite of all-cause death, target-vessel myocardial infarction (MI), or target-vessel revascularization. Among the study population, 231 patients (233 vessels) underwent PCI and 99 patients (105 vessels) were deferred. During 5 years of follow-up, cumulative incidence of MACE was 13.0% (31 patients) without significant difference between PCI and deferred groups (12.7% vs. 14.0%, adjusted HR 1.301, 95% CI 0.611-2.769, P = 0.495). Multiple sensitivity analyses by propensity score matching and inverse probability weighting also showed no significant difference in patient-level MACE and vessel-specific MI or revascularization. In this hypothesis-generating study, there was no significant difference in clinical outcomes between PCI and deferred groups among patients with intermediate stenosis with FFR ≤ 0.80 but CFR > 2.0. Further study is needed to confirm this finding.Clinical Trial Registration: International Collaboration of Comprehensive Physiologic Assessment Registry (NCT03690713; registration date: 10/01/2018).

Sweat the small stuff: The human microvasculature and heart disease

Traditionally thought of primarily as the predominant regulator of myocardial perfusion, it is becoming more accepted that the human coronary microvasculature also exerts a more direct influence on the surrounding myocardium. Coronary microvascular dysfunction (CMD) not only precedes large artery atherosclerosis, but is associated with other cardiovascular diseases such as heart failure with preserved ejection fraction and hypertrophic cardiomyopathy. It is also highly predictive of cardiovascular events in patients with or without atherosclerotic cardiovascular disease. This review focuses on this recent paradigm shift and delves into the clinical consequences of CMD. Concepts of how resistance arterioles contribute to disease will be discussed, highlighting how the microvasculature may serve as a potential target for novel therapies and interventions. Finally, both invasive and non-invasive methods with which to assess the coronary microvasculature both for diagnostic and risk stratification purposes will be reviewed.

Effects of salvianolate on microcirculatory disturbance in patients with stable coronary heart disease: study protocol for a randomized controlled trial

BACKGROUND

Obstruction of coronary microcirculation can lead to myocardial ischemia and poor prognosis. Salvianolate exerts cardiovascular protection at cellular levels. However, no studies have confirmed the effect of salvianolate on stable coronary heart disease (CHD) with high fractional flow reserve (FFR) and myocardial microcirculatory disturbances.

METHODS/DESIGN

This study will enroll 78 patients who have stable coronary disease with 50 to 70% stenosis in major coronary arteries and whose FFR > 0.80 and index of microcirculatory resistance (IMR) > 25. Patients will be randomly divided into the salvianolate group or the placebo group. After above evaluations, salvianolate 200 mg will be intravenously dripped immediately for the next 30 min and subsequent 7 days in the salvianolate group, and matching 0.9% normal saline will be arranged in the placebo group. IMR will be reevaluated in immediate phase after first 30 min of salvianolate or placebo treatment. The primary end point will be the IMR change in this phase, and the secondary end points will be the total ischemic burden assessed by the Seattle angina scale, quality of life scale, Holter electrocardiography, and 6-min walk test after 7 days before discharge.

DISCUSSION

This study will firstly clarify the improvement effect of salvianolate on coronary microcirculation and provide an effective treatment method for stable CHD patients with high FFR and myocardial microcirculatory disturbance.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR1800018772 . Registered on 9 October 2018 and updated on 2 March 2020.

Simulation of oxygen transport and estimation of tissue perfusion in extensive microvascular networks: Application to cerebral cortex

Advanced imaging techniques have made available extensive three-dimensional microvascular network structures. Simulation of oxygen transport by such networks requires information on blood flow rates and oxygen levels in vessels crossing boundaries of the imaged region, which is difficult to obtain experimentally. Here, a computational method is presented for estimating blood flow rates, oxygen levels, tissue perfusion and oxygen extraction, based on incomplete boundary conditions. Flow rates in all segments are estimated using a previously published method. Vessels crossing the region boundary are classified as arterioles, capillaries or venules. Oxygen levels in inflowing capillaries are assigned based on values in outflowing capillaries, and similarly for venules. Convective and diffusive oxygen transport is simulated. Contributions of each vessel to perfusion are computed in proportion to the decline in oxygen concentration along that vessel. For a vascular network in the mouse cerebral cortex, predicted tissue oxygen levels show a broad distribution, with 99% of tissue in the range of 20 to 80 mmHg under reference conditions, and steep gradients near arterioles. Perfusion and extraction estimates are consistent with experimental values. A 30% reduction in perfusion or a 30% increase in oxygen demand, relative to reference levels, is predicted to result in tissue hypoxia.

Prognostic significance of thermodilution-derived coronary flow capacity in patients with deferred revascularisation

AIMS

The aim of this study was to investigate the prognostic value of thermodilution-derived coronary flow capacity (T-CFC) in patients with stable coronary artery disease and deferred revascularisation.

METHODS AND RESULTS

We evaluated 308 lesions in 308 patients with deferred revascularisation, stratifying the cohort according to T-CFC. Ischaemic T-CFC was defined as a composite of mildly, moderately, and severely reduced T-CFC. Clinical outcomes were assessed by vessel-oriented composite endpoints (VOCE) and major adverse cardiac events (MACE). VOCE and MACE occurred in 19 and 28 patients, respectively. Ischaemic T-CFC was found in 88 lesions (28.6%). Kaplan-Meier analysis revealed that lesions with ischaemic T-CFC had a significantly higher risk of both VOCE and MACE. The net reclassification index and integrated discrimination improvement index were both significantly improved when ischaemic T-CFC was added to the clinical risk model (age, sex, prior stent implantation, and lesion length) for predicting VOCE and MACE. Furthermore, ischaemic T-CFC showed significant incremental predictive ability for VOCE and MACE when compared with the clinical risk model + fractional flow reserve ≤0.8, or with the clinical model + coronary flow reserve ≤2.0.

CONCLUSIONS

T-CFC categorisation improved the risk stratification for both VOCE and MACE and showed incremental prognostic value in patients with deferred revascularisation.

Comparison of antiangina therapies in patients with coronary heart disease in China: study protocol for a multicentre, retrospective, hospital system-based study

INTRODUCTION

China has the largest number of patients with coronary heart disease (CHD) in the world. Numerous pharmacological strategies are available for CHD in routine clinical practice. CHD-induced angina pectoris affects patients' quality of life and is a key predictor of prognosis. This study will compare the effectiveness of different antiangina treatments, particularly ATP-sensitive potassium channel (KATP) activators, in the Central China District. This proposal underpins the first comparison of antiangina therapies in patients with CHD in China using a multicentre, retrospective, hospital system-based assessment.

METHODS AND ANALYSIS

This retrospective real-world study will assess the largest hospital databases in Wuhan City in Central China to evaluate outcomes including mortality, revascularisation, myocardial infarction (MI), stroke and other cardio-cerebrovascular events in patients with CHD. Data will be consecutively collected between 1 April 2009 and 31 August 2019 through the hospital information system, laboratory information system and hospital imaging system. All data will be standardised by at least three independent technicians and statisticians using International Classification of Diseases Tenth Version, ISO15189 and Specification for Drafting of Basic Dataset of Electronic Medical Record (WS445). The data will include patient demographics, physical and laboratory examinations, imaging examinations, medical history, diagnosis, treatment options and payment information. We will compare KATP activators with other antiangina drugs using propensity score matching. The primary outcome will be major adverse cardiovascular events, defined as a composite of death, MI, stroke and rehospitalisation due to angina.

ETHICS AND DISSEMINATION

The current study is designed to translate research into improved care for patients. The institutional review board of Wuhan Tongji Hospital (Liao Jiazhi, Du Aiye, Chen Zhishui, Fang Feng, Yu Shiying, Liu Dong and Li Yaping) approved the study protocol (version 1.0, July 2019, approval number TJ-IRB201909112). Here we reported a protocol related to a pre-results. Data will be presented in peer-reviewed journals, social media and relevant conferences.

TRIAL REGISTRATION NUMBER

ChiCTR1900027812; Pre-results.

Microvascular Dysfunction in Diabetes Mellitus and Cardiometabolic Disease

This review takes an inclusive approach to microvascular dysfunction in diabetes mellitus and cardiometabolic disease. In virtually every organ, dynamic interactions between the microvasculature and resident tissue elements normally modulate vascular and tissue function in a homeostatic fashion. This regulation is disordered by diabetes mellitus, by hypertension, by obesity, and by dyslipidemia individually (or combined in cardiometabolic disease), with dysfunction serving as an early marker of change. In particular, we suggest that the familiar retinal, renal, and neural complications of diabetes mellitus are late-stage manifestations of microvascular injury that begins years earlier and is often abetted by other cardiometabolic disease elements (eg, hypertension, obesity, dyslipidemia). We focus on evidence that microvascular dysfunction precedes anatomic microvascular disease in these organs as well as in heart, muscle, and brain. We suggest that early on, diabetes mellitus and/or cardiometabolic disease can each cause reversible microvascular injury with accompanying dysfunction, which in time may or may not become irreversible and anatomically identifiable disease (eg, vascular basement membrane thickening, capillary rarefaction, pericyte loss, etc.). Consequences can include the familiar vision loss, renal insufficiency, and neuropathy, but also heart failure, sarcopenia, cognitive impairment, and escalating metabolic dysfunction. Our understanding of normal microvascular function and early dysfunction is rapidly evolving, aided by innovative genetic and imaging tools. This is leading, in tissues like the retina, to testing novel preventive interventions at early, reversible stages of microvascular injury. Great hope lies in the possibility that some of these interventions may develop into effective therapies.

Impaired coronary flow velocity reserve is associated with cardiovascular risk factors but not with angina symptoms

OBJECTIVES

Coronary microvascular dysfunction (CMD) is considered to cause angina pectoris in a large proportion of women with no obstructive coronary artery disease (CAD). However, data supporting a relation between angina pectoris and CMD are limited. We compared CMD in women with angina with asymptomatic women and evaluated the relation between presence of CMD, angina characteristics, cardiovascular risk factors and results of stress testing.

METHODS

In a cross-sectional study, we included 1684 women with angina and <50% coronary artery stenosis on invasive angiography. Asymptomatic women from the community-based Copenhagen City Heart Study served as reference group (n=102). Coronary microvascular function was determined by coronary flow velocity reserve (CFVR) assessed by transthoracic Doppler stress echocardiography. CFVR < 2 was defined as CMD. Symptoms were obtained from standardised angina questionnaires and results of stress testing from health records.

RESULTS

Median CFVR was 2.33 (IQR 2.00-2.75) in symptomatic women versus 2.60 (2.19-2.95) in asymptomatic (p=0.007). CFVR <2 was found in 25% of symptomatic and in 19% of asymptomatic women. Symptomatic women had a greater risk factor burden. After adjusting for age, hypertension, diabetes, smoking and heart rate the difference in CFVR between groups disappeared (p=0.213). We found no associations between CFVR and angina characteristics, symptom burden or results from stress testing.

CONCLUSIONS

Impaired CFVR is more prevalent in symptomatic than in asymptomatic women and related to the cardiovascular risk factors hypertension, diabetes, smoking and increased heart rate. Neither a positive bicycle test, single photon emission CT stress test nor chest pain characteristics identify women with impaired CFVR among women with angina and no obstructive CAD. Results may question the concept of microvascular angina as currently defined.

Functional assessment of myocardial ischaemia by intracoronary ECG

Introduction

In patients with chronic coronary syndrome, percutaneous coronary intervention targets haemodynamically significant stenoses, that is, those thought to cause ischaemia. Intracoronary ECG (icECG) detects ischaemia directly where it occurs. Thus, the goal of this study was to test the accuracy of icECG during pharmacological inotropic stress to determine functional coronary lesion severity in comparison to the structural parameter of quantitative angiographic per cent diameter stenosis (%S), as well as to the haemodynamic indices of fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR).

Method

The primary study endpoint of this prospective trial was the maximal change in icECG ST-segment shift during pharmacological inotropic stress induced by dobutamine plus atropine obtained within 1 min after reaching maximal heart rate(=220 - age). IcECG was acquired by attaching an alligator clamp to the angioplasty guidewire positioned downstream of the stenosis. For the pressure-derived stenosis severity ratios, coronary perfusion pressure and simultaneous aortic pressure were continuously recorded.

Results

There was a direct linear relation between icECG ST-segment shift and %S: icECG=−0.8+0.03*%S (r²=0.164; p<0.0001). There were inverse linear correlations between FFR and %S: FFR=1.1–6.1*10–3*%S (r²=0.494; p<0.0001), and between iFR and %S: iFR=1.27–8.6*10–3*%S (r²=0.461; p<0.0001). Using a %S-threshold of ≥50% as the reference for structural stenosis relevance, receiver operating characteristics-analysis of absolute icECG ST-segment shift during hyperemia showed an area under the curve (AUC) of 0.678±0.054 (p=0.002; sensitivity=85%, specificity=50% at 0.34 mV). AUC for FFR was 0.854±0.037 (p<0.0001; sensitivity=64%, specificity=96% at 0.78), and for iFR it was 0.816±0.043 (p<0.0001;sensitivity=62%, specificity=96% at 0.83).

Conclusions

Hyperaemic icECG ST-segment shift detects structurally relevant coronary stenotic lesions with high sensitivity, while they are identified highly specific by FFR and iFR.

Predictors of recurrent angina in patients with no need for secondary revascularization

BACKGROUND

Approximately 20% to 30% of patients with coronary artery disease (CAD) develop recurrent angina pectoris following successful and complete coronary revascularization utilizing percutaneous coronary intervention (PCI). We aim to investigate predictors of recurrent angina pectoris in patients who have undergone successful coronary revascularization using PCI, but on repeat coronary angiography have no need for secondary revascularization.

METHODS

The study comprised 3,837 patients with CAD, who were enrolled from January 2007 to June 2019. They had undergone successful PCI; some of them redeveloped angina pectoris within one year after the procedure, but on repeat coronary angiography had no need for revascularization. Thrombolysis in myocardial infarction (TIMI) frame count was used to evaluate the velocity of coronary blood in the follow-up angiogram. Multivariate logistic regression was used to investigate risk factors for recurrent angina pectoris. Similarly, predictors of recurrent angina according to the TIMI frame count were assessed using multivariate linear regression.

RESULTS

In this retrospective study, 53.5% of patients experienced recurrent angina pectoris. By multivariate logistic regression, the following characteristics were statistically identified as risk factors for recurrent angina pectoris: female sex, older age, current smoking, low-density lipoprotein cholesterol (LDL-C) ≥1.8 mmol/L, and an elevated TIMI frame count (P for all <0.05). Similarly, using multivariate linear regression, the statistical risk factors for TIMI frame count included: female sex, older age, diabetes, body mass index (BMI), post-procedural treatment without the inclusion of dual antiplatelet therapy.

CONCLUSIONS

Patient characteristics of female sex, older age, diabetes, and elevated BMI are associated with an increased TIMI frame count, coronary microcirculation dysfunction, and recurrent angina pectoris after initially successful PCI. In addition, current smoking and LDL-C ≥1.8 mmol/L are risk factors for recurrent angina pectoris. In contrast, the treatment with dual antiplatelet therapy is negatively correlated with a higher TIMI frame count and the risk of recurrent angina pectoris.

Effects of impaired microvascular flow regulation on metabolism-perfusion matching and organ function

Impaired tissue oxygen delivery is a major cause of organ damage and failure in critically ill patients, which can occur even when systemic parameters, including cardiac output and arterial hemoglobin saturation, are close to normal. This review addresses oxygen transport mechanisms at the microcirculatory scale, and how hypoxia may occur in spite of adequate convective oxygen supply. The structure of the microcirculation is intrinsically heterogeneous, with wide variations in vessel diameters and flow pathway lengths, and consequently also in blood flow rates and oxygen levels. The dynamic processes of structural adaptation and flow regulation continually adjust microvessel diameters to compensate for heterogeneity, redistributing flow according to metabolic needs to ensure adequate tissue oxygenation. A key role in flow regulation is played by conducted responses, which are generated and propagated by endothelial cells and signal upstream arterioles to dilate in response to local hypoxia. Several pathophysiological conditions can impair local flow regulation, causing hypoxia and tissue damage leading to organ failure. Therapeutic measures targeted to systemic parameters may not address or may even worsen tissue oxygenation at the microvascular level. Restoration of tissue oxygenation in critically ill patients may depend on restoration of endothelial cell function, including conducted responses.

Coronary provocative tests in the catheterization laboratory: Pathophysiological bases, methodological considerations and clinical implications

The paradigm for the management of patients presenting with angina and/or myocardial ischemia has been historically centered on the detection and treatment of obstructive coronary artery disease (CAD). However, in a considerable proportion (30-50%) of patients undergoing coronary angiography, obstructive CAD is excluded. Thus, functional mechanisms may be involved in determining myocardial ischemia and should be investigated. In particular, coronary vasomotor disorders both at epicardial and at microvascular level may play a crucial role, but a definitive diagnosis of these disorders can at times be difficult, given the transience of symptoms, and often requires the use of coronary provocative tests. Of importance, these tests may provide relevant information on the pathogenic mechanism of myocardial ischemia, allowing physicians to tailor the therapies of their patients. Furthermore, several studies underscored the important prognostic information deriving from the use of coronary provocative tests. Nevertheless, their use in clinical practice is currently limited and mainly restricted to specialized centers, with only a minority of patients receiving a benefit from this diagnostic approach. In this review, we explain the pathophysiological bases for the use of provocative tests, along with their clinical, prognostic and therapeutic implications.

Prognostic value of myocardial perfusion scintigraphy in diabetic patients and without coronary lesion

OBJECTIVE

To determine the prognostic value of myocardial perfusion scintigraphy-gated SPECT in patients with diabetes mellitus and without obstructive coronary artery disease.

MATERIALS AND METHODS

This retrospective study included consecutive patients undergoing adenosine stress-rest myocardial perfusion imaging (MPI) by ^99mTc-tetrofosmin between 2009 and 2011. The patients had diabetes mellitus and coronary angiography without significant coronary lesions. In total, 37 diabetic patients (female/male: 20/17; mean age: 65.2 (range: 40-78). 29 non-diabetic patients were included wich are matched with the group of diabetic patients with positive MPI. The group of non-diabetic patients had scintigraphy with myocardial ischemia and without angiographic lesions. A 36-month clinical follow-up was performed, and major cardiac events were recorded.

RESULTS

In 78.3% (29/37) of diabetic patients the scintigraphic study showed myocardial ischemia, while it was negative in the 21.7%. The cardiac event rate in both groups was 6%. In diabetics with a myocardial perfusion study with myocardial ischemia, there were 3 major cardiac events. In diabetic patients with negative study had no cardiac event. In the non-diabetic control group the cardiac events rate was 3.4% (1/29).

CONCLUSION

In diabetic patients without obstructive coronary disease, myocardial perfusion study can be predictor of cardiac events. A negative study can be an indicator of a better cardiovascular prognosis.

Role of acetylcholine spasm provocation test as a pathophysiological assessment in nonobstructive coronary artery disease

Coronary angiography (CAG) sometimes shows nonobstructive coronary arteries in patients with suspected angina or acute coronary syndrome (ACS). The high prevalence of nonobstructive coronary artery disease (CAD) in those patients has recently been reported not only in Japan but also in Western countries, and is clinically attracting attention. Coronary spasm is considered to be one of the leading causes of both suspected stable angina and ACS with nonobstructive coronary arteries. Coronary spasm could also be associated with left ventricular dysfunction leading to heart failure, which could be improved following the administration of calcium channel blockers. Because we rarely capture spontaneous attacks of coronary spasm with electrocardiograms or Holter recordings, an invasive diagnostic modality, acetylcholine (ACh) provocation test, can be useful in detecting coronary spasm during CAG. Furthermore, we can use the ACh-provocation test to identify high-risk patients with coronary spasm complicated with organic coronary stenosis, and then treat with intensive care. Nonobstructive CAD includes not only epicardial coronary spasm but also microvascular spasm or dysfunction that can be associated with recurrent anginal attacks and poor quality of life. ACh-provocation test could also be helpful for the assessment of microvascular spasm or dysfunction. We hope that cardiologists will increasingly perform ACh-provocation test to assess the pathophysiology of nonobstructive CAD.

Coronary microvascular dysfunction in stable ischaemic heart disease (non-obstructive coronary artery disease and obstructive coronary artery disease)

Diffuse and focal epicardial coronary disease and coronary microvascular abnormalities may exist side-by-side. Identifying the contributions of each of these three players in the coronary circulation is a difficult task. Yet identifying coronary microvascular dysfunction (CMD) as an additional player in patients with coronary artery disease (CAD) may provide explanations of why symptoms may persist frequently following and why global coronary flow reserve may be more prognostically important than fractional flow reserve measured in a single vessel before percutaneous coronary intervention. This review focuses on the challenges of identifying the presence of CMD in the context of diffuse non-obstructive CAD and obstructive CAD. Furthermore, it is going to discuss the pathophysiology in this complex situation, examine the clinical context in which the interaction of the three components of disease takes place and finally look at non-invasive diagnostic methods relevant for addressing this question.

Mechanisms and diagnostic evaluation of persistent or recurrent angina following percutaneous coronary revascularization

Persistence or recurrence of angina after a percutaneous coronary intervention (PCI) may affect about 20-40% of patients during short-medium-term follow-up. This appears to be true even when PCI is 'optimized' using physiology-guided approaches and drug-eluting stents. Importantly, persistent or recurrent angina post-PCI is associated with a significant economic burden. Healthcare costs may be almost two-fold higher among patients with persistent or recurrent angina post-PCI vs. those who become symptom-free. However, practice guideline recommendations regarding the management of patients with angina post-PCI are unclear. Gaps in evidence into the mechanisms of post-PCI angina are relevant, and more research seems warranted. The purpose of this document is to review potential mechanisms for the persistence or recurrence of angina post-PCI, propose a practical diagnostic algorithm, and summarize current knowledge gaps.

Genetic dysregulation of endothelin-1 is implicated in coronary microvascular dysfunction

AIMS

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide linked to vascular diseases through a common intronic gene enhancer [(rs9349379-G allele), chromosome 6 (PHACTR1/EDN1)]. We performed a multimodality investigation into the role of ET-1 and this gene variant in the pathogenesis of coronary microvascular dysfunction (CMD) in patients with symptoms and/or signs of ischaemia but no obstructive coronary artery disease (CAD).

METHODS AND RESULTS

Three hundred and ninety-one patients with angina were enrolled. Of these, 206 (53%) with obstructive CAD were excluded leaving 185 (47%) eligible. One hundred and nine (72%) of 151 subjects who underwent invasive testing had objective evidence of CMD (COVADIS criteria). rs9349379-G allele frequency was greater than in contemporary reference genome bank control subjects [allele frequency 46% (129/280 alleles) vs. 39% (5551/14380); P = 0.013]. The G allele was associated with higher plasma serum ET-1 [least squares mean 1.59 pg/mL vs. 1.28 pg/mL; 95% confidence interval (CI) 0.10-0.53; P = 0.005]. Patients with rs9349379-G allele had over double the odds of CMD [odds ratio (OR) 2.33, 95% CI 1.10-4.96; P = 0.027]. Multimodality non-invasive testing confirmed the G allele was associated with linked impairments in myocardial perfusion on stress cardiac magnetic resonance imaging at 1.5 T (N = 107; GG 56%, AG 43%, AA 31%, P = 0.042) and exercise testing (N = 87; -3.0 units in Duke Exercise Treadmill Score; -5.8 to -0.1; P = 0.045). Endothelin-1 related vascular mechanisms were assessed ex vivo using wire myography with endothelin A receptor (ETA) antagonists including zibotentan. Subjects with rs9349379-G allele had preserved peripheral small vessel reactivity to ET-1 with high affinity of ETA antagonists. Zibotentan reversed ET-1-induced vasoconstriction independently of G allele status.

CONCLUSION

We identify a novel genetic risk locus for CMD. These findings implicate ET-1 dysregulation and support the possibility of precision medicine using genetics to target oral ETA antagonist therapy in patients with microvascular angina.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03193294.

Coronary Microvascular Dysfunction

Many patients with chest pain undergoing coronary angiography do not show significant obstructive coronary lesions. A substantial proportion of these patients have abnormalities in the function and structure of coronary microcirculation due to endothelial and smooth muscle cell dysfunction. The coronary microcirculation has a fundamental role in the regulation of coronary blood flow in response to cardiac oxygen requirements. Impairment of this mechanism, defined as coronary microvascular dysfunction (CMD), carries an increased risk of adverse cardiovascular clinical outcomes. Coronary endothelial dysfunction accounts for approximately two-thirds of clinical conditions presenting with symptoms and signs of myocardial ischemia without obstructive coronary disease, termed "ischemia with non-obstructive coronary artery disease" (INOCA) and for a small proportion of "myocardial infarction with non-obstructive coronary artery disease" (MINOCA). More frequently, the clinical presentation of INOCA is microvascular angina due to CMD, while some patients present vasospastic angina due to epicardial spasm, and mixed epicardial and microvascular forms. CMD may be associated with focal and diffuse epicardial coronary atherosclerosis, which may reinforce each other. Both INOCA and MINOCA are more common in females. Clinical classification of CMD includes the association with conditions in which atherosclerosis has limited relevance, with non-obstructive atherosclerosis, and with obstructive atherosclerosis. Several studies already exist which support the evidence that CMD is part of systemic microvascular disease involving multiple organs, such as brain and kidney. Moreover, CMD is strongly associated with the development of heart failure with preserved ejection fraction (HFpEF), diabetes, hypertensive heart disease, and also chronic inflammatory and autoimmune diseases. Since coronary microcirculation is not visible on invasive angiography or computed tomographic coronary angiography (CTCA), the diagnosis of CMD is usually based on functional assessment of microcirculation, which can be performed by both invasive and non-invasive methods, including the assessment of delayed flow of contrast during angiography, measurement of coronary flow reserve (CFR) and index of microvascular resistance (IMR), evaluation of angina induced by intracoronary acetylcholine infusion, and assessment of myocardial perfusion by positron emission tomography (PET) and magnetic resonance (CMR).

A Review of the Evidence for Treatment of Myocardial Infarction With Nonobstructive Coronary Arteries

Myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA) is reported in 6% of patients with acute MI referred for catheterization. Because of the complex etiology and a limited amount of evidence, the treatment of MINOCA remains elusive. The etiology of MINOCA manifests from several causes including plaque disruption or erosion, epicardial coronary artery vasospasm, and coronary microvascular dysfunction. In addition, spontaneous coronary artery dissection, takotsubo, and myocarditis have been identified as contributing to the diagnosis of MINOCA. Patients with MINOCA are frequently young, non-white females with fewer traditional risk factors compared with those with an MI caused by obstructive coronary disease. Moreover, women who suffered an MI are 5 times more likely to be diagnosed with MINOCA with a trend for worse outcomes compared with men. The increased recognition/diagnosis of MINOCA has highlighted a gap in our understanding of the treatment of MINOCA. This review identified that there is a paucity of evidence on treatment strategies for patients clinically diagnosed with MINOCA, but more importantly that MINOCA should be viewed as a "syndrome" with many different pathologic causes. This suggests that a standard protocol may not be useful for patients with MINOCA. Given the ongoing debate over the complexity of MINOCA, the main focus in the management of MINOCA should be to identify the underlying mechanism for targeted therapies that may optimize outcomes.

Clinical outcomes in patients with primary stable microvascular angina: is the jury still out?

Several studies have demonstrated that angina chest pain in presence of normal or near normal coronary arteries (NCAs) is mainly related to coronary microvascular dysfunction (CMD). However, controversial findings exist about clinical outcome of these patients. In this article, we critically review characteristics and results of the main clinical studies reporting clinical outcome of stable patients with angina chest pain and non-obstructive coronary artery disease (NO-CAD). Published data indicate that clinical outcomes of these patients are heterogeneous, but those with strict criteria for primary stable microvascular angina (MVA, i.e. typical angina with NCAs mainly related to efforts) do not appear to have an increased mortality or risk of major coronary events. A major determinant of outcome in patients with MVA and NO-CAD seems instead related to non-critical atherosclerotic disease, the presence of which should suggest a more aggressive management of cardiovascular risk factors and preventive management. Future studies should assess whether CMD may have a relevant prognostic role in the latter clinical context and/or in other clinical settings of NO-CAD different from primary stable MVA.

Role of the central autonomic nervous system intrinsic functional organisation and psychosocial factors in primary microvascular angina and Takotsubo syndrome

Introduction and objective

Dysfunctional central autonomic nervous system network (CAN) at rest may result in aberrant autonomic responses to psychosocial stressors. We hypothesised that patients with primary microvascular angina (MVA) or Takotsubo syndrome (TTS) would exhibit a peculiar functional organisation of the CAN, potentially associated with psychological patterns.

Methods

Patients underwent a psychosocial evaluation: a clinical diagnostic interview, Millon Clinical Multiaxial Inventory III, State-Trait Anxiety Inventory form Y and Short Form 36 Health Survey (SF-36). The strength of intrinsic functional connectivity (FC) between various nodes of the CAN was investigated using cerebral resting state functional MRI (RS-fMRI).

Results

We evaluated 50 (46 women) stable patients: 16 patients with MVA, 17 patients with TTS and 17 patients with previous acute myocardial infarction (AMI). Compared with AMI, patients with MVA showed a lower (higher impairment) SF-36 Body-Pain score (p 0.046) and a higher SF-36 Mental-Health score (p 0.039). Patients with TTS showed the strongest FC between two nodes of the CAN (sympathetic midcingulate cortex and parasympathetic primary motor area) (F 6.25, p 0.005) using RS-fMRI.

Conclusions

The study implements an innovative collaborative research among cardiologists, neuroscientists and psychiatrists (‘Neuro-psycho-heart Team’). MVA showed a discrepancy between the highest level of self-reported body pain and the best mental health score, which might suggest a mechanism of somatisation. TTS exhibited an increased functional integration between two areas of the CAN involved in interoceptive pain awareness and negative emotional status. We implemented an innovative research collaboration among cardiologists, neuroscientists and psychiatrists. These data are hypothesis generating and suggest potential prospective investigations on pathophysiology and implementation of psychotherapy and stress-reducing techniques as therapeutic strategies.

Trial registration number

NCT02759341.

Effect of Chinese medicine for promoting blood circulation on microvascular angina: A systematic review and meta-analysis

BACKGROUND

Blood-activating drugs (BADs) are widely used to treat microvascular angina in China. This study aims to summarize relevant evidence from randomized controlled trials (RCTs) to assess the efficacy and safety of BADs in the treatment of microvascular angina.

METHODS

We searched for relevant studies before June 2019 from seven databases. Twenty-four studies were included of 1903 patients with microvascular angina. All studies compared the use of traditional Chinese medicine for activating blood circulation (BADs) and Western medicine (WM) with the use of Western medicine alone.

RESULTS

In all, 15 trials reported a significant effect of BADs on improving clinical symptoms compared with the control treatment (P < .00001), and 8 trials reported significant effects of BADs on reducing the frequency of angina pectoris attacks compared with Western medicine treatment (P < .00001). The pooled results also demonstrated that BADs provided a significant benefit in reducing the dosage of nitroglycerin required (P = .02), the maximum range of ST-segment depression (P = .003) and the descending degree of the ST-T segment of ECG (P = .0002); prolonging the total time of treadmill exercise (P < .00001) and the time of ST-segment depression of 1 mm (P = .002); enhancing the total effective rate of Traditional Chinese Medicine (TCM) syndromes (P < .00001); improving endothelial function (P < .00001); and reducing the levels of high-sensitivity C-reactive protein (hs-CRP) (P < .00001). BAD treatment showed no statistically significant effect on the levels of TNF-a (P = .8) or IL-6 (P = .13). No severe adverse events were reported.

CONCLUSION

This meta-analysis shows that BADs are effective for the treatment of microvascular angina. Although concerns regarding selective bias and low methodological quality were raised, our findings suggest that BADs are beneficial for patients with microvascular angina and should be given priority for future clinical studies.

Index of Microcirculatory Resistance Measured during Intracoronary Adenosine-Induced Hyperemia

Background

The index of microcirculatory resistance is an invasive measure of coronary microvascular function that has to be calculated during maximal hyperemia, classically achieved with intravenous adenosine (IV). The aim of this study was to evaluate the use of intracoronary (IC) adenosine for the calculation of IMR.

Methods and Results

31 patients with stable coronary artery disease were included in the study. Coronary pressure and thermodilution measurements were obtained at rest and during maximal hyperemia using a pressure-temperature sensor-tipped coronary guidewire. Duplicate measurements were performed using first IC and then IV adenosine. Dispersion of transit times was comparable for IC and IV adenosine. IMR values based on IC vs IV adenosine showed a high level of agreement and an intraclass correlation coefficient of 0.90. Applying an upper normal limit of 25, misclassification of IMR using IC adenosine was seen in just one patient in whom IC adenosine resulted in a lower value. A simplified procedure based on a single bolus dose of saline did not change the level of agreement or the rate of misclassification.

Conclusions

We found an excellent agreement between IMR values measured during hyperemia induced by IC as compared to IV adenosine. The use of IC adenosine may facilitate invasive assessment of microvascular function and is potentially time- and cost-saving with less patient discomfort as compared to IV infusion. The trail is registered with NCT03369184.

Acute Coronary Syndrome with Non-ruptured Plaques (NONRUPLA): Novel Ideas and Perspectives

PURPOSE OF REVIEW

In this review article, we focus on the mechanisms and features of acute coronary syndromes (ACS) with no ruptured plaque (NONRUPLA) highlighting the uncertainties over diagnostic evaluation and treatment.

RECENT FINDINGS

The most common cause of ACS is obstruction due to atherosclerotic plaque ruptured or erosion. In 14% of patients who present in the Emergency Department as myocardial infarction, the final diagnosis is ACS with NONRUPLA. Although the clinical presentation of NONRUPLA may mimic myocardial infarction, the underlying pathogenesis is different, and it may guide therapeutic approaches and overall prognosis that vary according to etiology. The possible mechanisms of ACS with NONRUPLA are coronary embolism, acute dissection of the aorta or coronary artery, vasospasm, microvascular dysfunction, the imbalance between oxygen demand and supply, coronary trauma and stent complications, direct cellular toxicity and damage, Takotsubo syndrome, and myocardial infarction with non-obstructive coronary arteries (MINOCA).

Echocardiographic measurement of epicardial adipose tissue thickness in patients with microvascular angina

Introduction

Impaired coronary microcirculation, inflammation, and endothelial dysfunction were reported etiological factors for microvascular angina (MVA). Recently, increased epicardial adipose tissue (EAT) thickness has been associated with hypertension, metabolic syndrome, and coronary artery disease in general population. In this study, we aimed to evaluate the EAT thickness in patients with MVA.

Methods

This study enrolled 200 patients (83 males; mean age: 55.4 ± 8.2 years) who have been diagnosed with MVA and 200 controls (89 males; mean age: 54.4 ± 8.5 years). All patients underwent transthoracic echocardiography, and EAT thickness was measured from a parasternal long-axis view as the hypoechoic space on the right ventricular free wall.

Results

The mean EAT thickness was significantly higher in MVA patients than the controls (5.5 ± 1.1 vs. 4.9 ± 0.7 mm; p < 0.001). Multiple logistic regression analysis showed that increased EAT thickness was an independent predictor of MVA (OR = 1.183, 95% CI = 1.063-1.489; p = 0.023). In receiver operating characteristic curve analyses, EAT thickness above 5.3 mm predicted MVA with a sentivity of 68% and a specificity of 63% (AUC = 0.711, 95% CI = 0.659-0.762; p < 0.001).

Conclusions

The EAT thickness was observed significantly higher in MVA patients as compared to controls. Increased EAT thickness may be associated with mechanisms that play a major role in the pathogenesis of MVA.

Determining the Significance of Coronary Plaque Lesions: Physiological Stenosis Severity and Plaque Characteristics

The evaluation of coronary lesions has evolved in recent years. Physiologic-guided revascularization (particularly with pressure-derived fractional flow reserve (FFR)) has led to superior outcomes compared to traditional angiographic assessment. A greater importance, therefore, has been placed on the functional significance of an epicardial lesion. Despite the improvements in the limitations of angiography, insights into the relationship between hemodynamic significance and plaque morphology at the lesion level has shown that determining the implications of epicardial lesions is rather complex. Investigators have sought greater understanding by correlating ischemia quantified by FFR with plaque characteristics determined on invasive and non-invasive modalities. We review the background of the use of these diagnostic tools in coronary artery disease and discuss the implications of analyzing physiological stenosis severity and plaque characteristics concurrently.

Endothelial Vascular Function as a Surrogate of Vascular Risk and Aging in Women

Cardiovascular disease is the leading cause of morbidity and mortality in women. We suggest the need to develop a paradigm that connects sex- and age-specific nontraditional risk factors that serve as a common mechanism ultimately leading to an increased risk of cardiovascular events. Vascular injury with abnormal repair leading to functional, rather than structural, abnormalities can be regarded as accelerated vascular aging. It emerges as a common feature that can trigger the early diagnosis and risk stratification for cardiovascular disease in women. We discuss sex-specific risk factors that can contribute to vascular injury with age, and these might not always be considered by cardiovascular physicians. It is important for the primary physician to be aware of these risk factors to enable more intensified management of this at-risk population. Novel technologies that allow the assessment of vascular function noninvasively can serve as key diagnostic and therapeutic tools with which we can identify such individuals and target therapy to manage this important patient population appropriately and effectively. We hope that this article will stimulate interest in this field and encourage further research in these important areas.

Three-dimensional visualization of coronary microvasculature in rats with myocardial infarction

BACKGROUND

Assessment of the coronary microcirculation remains challenging.

OBJECTIVE

we explored the feasibility of evaluating the coronary microvasculature in rats with myocardial infarction (MI) using a three-dimensional visualization technique.

METHODS

Animals were divided into the sham operation group (S), MI 45 min group (M45), and MI 180 min group (M180). Opened microvessels were labelled with the fluorescent dye DiI (1, 1'-dioctadecyl-3, 3, 3'3'-tetramethylindo carbocyanine perchlorate) using a heart perfusion method. The microvascular distribution and opening status were observed under laser scanning confocal microscopy, which was adjusted to facilitate evaluation of subjects around 6 to 20 μm.

RESULTS

Microvascular vessels (6-20 μm) were successfully labelled by DiI. Intact and clear three-dimensional microvascular structures were observed in myocardium of sham rats and remote non-infarct myocardial tissue of MI rats, while there was almost no microvascular structure in the infarct area of the M45 group, and only a small amount of microvascular visualization was visualized in the infarct area of the M180 group. The microvascular area and microvascular density in M45 group and M180 group in the infarct border zone were significantly lower than corresponding area in S group.

CONCLUSION

Three-dimensional visualization of opened coronary microvascular vessels is feasible in DiI-labelled myocardium in this rat MI model. This novel technique might be useful for defining the underlying mechanisms of coronary microvascular diseases and observe the efficacy of various therapy strategies on coronary microvessels.

Coronary microvascular dysfunction

Patients with coronary microvascular dysfunction (CMVD) represent a widespread population and despite the good prognosis, many of them have a poor quality of life with strong limitations in their daily activities because of the angina symptoms. This article summarizes the most frequent clinical presentation pictures like stable and unstable microvascular angina. Main risk factors are discussed, followed by the latest updates on the subject about different pathogenic hypotheses, diagnosis and treatment. Not very well understood microvascular alterations, like slow flow phenomenon and no reflow are discussed and both prognosis and the impact of the disease in the quality of life are analyzed.

Management of Angina Post Percutaneous Coronary Intervention

PURPOSE OF REVIEW

Our review discusses the management of post percutaneous coronary intervention angina (PPCIA) which negatively impacts 20-40% of patients and imposes a high burden on the healthcare system.

RECENT FINDINGS

Mechanisms of PPCIA include microvascular dysfunction, distal coronary vasospasm or disease, microembolization, myocardial bridge, coronary artery disease (CAD) progression, and rarely stent thrombosis or in-stent restenosis. Nitrates, beta blockers (BB), calcium channel blockers, and ranolazine are the common medical management options. Only BB showed 1-year mortality benefit following myocardial infarction. Stress echocardiography and cardiac magnetic resonance are the best to detect CAD vs. microvascular dysfunction. Invasively, vasoprovocative testing and fractional flow reserve provide useful prognostic information. If the ischemia burden is ≤10%, conservative management should be considered based upon the individual patient scenario. The optimal management of PPCIA remains unclear and further research is necessary. Multiple treatment options exist, which should be implemented in an individualized fashion.