Myocardial perfusion echocardiography and coronary microvascular dysfunction

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

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

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

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

Coronary Microvascular Dysfunction: A Guide for Clinicians

Dysfunction of the coronary microvasculature has become increasingly recognized as an important mechanism of myocardial ischemia in patients without obstructive coronary artery disease. The causes and management of coronary microvascular dysfunction remain poorly understood and are still largely based on extrapolation of epicardial coronary artery disease data. Quantification of myocardial blood flow and flow reserve have improved diagnosis, though important questions remain. In this review, we explain current understanding of the spectrum of pathophysiology of coronary microvascular dysfunction, summarize current diagnostic techniques to assess for coronary microvascular dysfunction, and appraise the limited data on management options specifically for patients with coronary microvascular dysfunction.

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.

A Narrative Review of the Classical and Modern Diagnostic Methods of the No-Reflow Phenomenon

The incidence of the no-reflow (NR) phenomenon varies depending on the diagnostic criteria used. If just the angiographic criteria are considered (i.e., a degree of thrombolysis in myocardial infarction ≤2), it will be found that the incidence of NR is quite low; on the other hand, when the myocardial NR is taken into account (i.e., a decrease in the quality of myocardial reperfusion expressed by the degree of myocardial blush), the real incidence is higher. Thus, the early establishment of a diagnosis of NR and the administration of specific treatment can lead to its reversibility. Otherwise, regardless of the follow-up period, patients with NR have a poor prognosis. In the present work, we offer a comprehensive perspective on diagnostic tools for NR detection, for improving the global management of patients with arterial microvasculature damage, which is a topic of major interest in the cardiology field, due to its complexity and its link with severe clinical outcomes.

Research Progress of Imaging Methods for Detection of Microvascular Angina Pectoris in Diabetic Patients

Diabetes is a complex metabolic disease characterized by hyperglycemia. Its complications are various, often involving the heart, brain, kidney, and other essential organs. At present, the number of diabetic patients in the world is growing day by day. The cardiovascular disease caused by diabetes has dramatically affected the quality of life of diabetic patients. It is the leading cause of death of diabetic patients. Diabetic patients often suffer from microvascular angina pectoris without obstructive coronary artery disease. Still, there are typical ECG ischemia and angina pectoris, that is, chest pain and dyspnea under exercise. Unlike obstructive coronary diseases, nitrate does not affect chest pain caused by coronary microvascular angina in most cases. With the increasing emphasis on diabetic microvascular angina, the need for accurate diagnosis of the disease is also increasing. We can use SPECT, PET, CMR, MCE, and other methods to evaluate coronary microvascular function. SPECT is commonly used in clinical practice, and PET is considered the gold standard for non-invasive detection of myocardial blood flow. This article mainly introduces the research progress of these imaging methods in detecting microvascular angina in diabetic patients.

Echocardiographic assessment of coronary microvascular dysfunction: Basic concepts, technical aspects, and clinical settings

Coronary flow reserve is the capacity of the coronary circulation to augment the blood flow in response an increase in myocardial metabolic demands and has a powerful prognostic significance in different clinical situations. It might assess with invasive and noninvasive technique. Transthoracic echocardiography Doppler is an emerging diagnostic technique, noninvasive, highly feasible, safe for patient and physician, without radiation, and able to detect macrovascular and microvascular anomalies in the coronary circulation. This review aims to describe the benefit and limits of echocardiographic assessment of coronary flow reserve.

Myocardial Metastasis of Cutaneous Squamous Cell Carcinoma in a Burn Patient

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The patient presented with fungating skin lesions, remitting fevers, and leukocytosis.

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Myocardial perfusion echocardiography aided in the diagnosis of neoplasm in the RVOT.

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Fluoroscopy-guided biopsy of the mass confirmed metastatic invasion of SCC.

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Evidence for optimal management of cardiac metastasis of SCC is scarce.

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This is the first reported case of Marjolin's ulcer with metastasis to the heart.

Usefulness of Left Ventricular Vortex Flow Analysis for Predicting Clinical Outcomes in Patients with Chronic Heart Failure: A Quantitative Vorticity Imaging Study Using Contrast Echocardiography

The goal of the study described here was to evaluate whether left ventricular vortex flow parameters, as assessed by contrast echocardiography, enhance prediction of major adverse cardiac events (MACE) in patients with chronic heart failure and systolic dysfunction. A total of 75 patients with contrast echocardiography and systolic dysfunction (ejection fraction ≤45%) were prospectively enrolled and underwent vortex flow analysis with particle image velocimetry using contrast echocardiography. Vortex flow parameters, including kinetic energy fluctuation (KEF), were evaluated. Patients were followed up for a primary endpoint of MACE that comprised hospital admission for cardiovascular causes and cardiac deaths. Across a median 277-d follow-up, 29 patients (38.7%) experienced MACE. Among these, the incidence of diabetes and the E/e' ratio were significantly higher in patients with MACE than in those without, whereas the hemoglobin level and ejection fraction were significantly lower. KEF was significantly lower in patients with MACE. In the multivariate analysis, higher KEF was associated with a lower risk of MACE (hazard ratio = 0.18, 95% confidence interval: 0.04-0.97, p = 0.046). The addition of KEF to a model with conventional parameters (e.g., age, diabetes, ejection fraction and the E/e' ratio) significantly improved the model's discrimination. Elevations in the quantitative left ventricular vortex flow parameter, KEF, as determined by contrast echocardiography, are associated with a lower risk of MACE and improved functional status among patients with chronic heart failure.

Reversible impairment of coronary flow reserve in acute myocarditis

OBJECTIVE

Acute myocarditis is accompanied by an impaired coronary microcirculation. These microcirculatory disturbances are not well defined, and data are derived from complex invasive measurements. Therefore, this study aimed to evaluate the inflammation-induced microcirculatory dysfunction including its reversibility and association with markers of inflammation severity (extent of LGE on CMR imaging and laboratory markers of myocardial necrosis) using the noninvasive technique of echocardiographic CFR measurement.

METHODS

Patients (n = 14) with clinically suspected acute myocarditis in the absence of coronary artery disease were prospectively enrolled, and echocardiographic CFR was determined by measuring peak diastolic coronary blood flow velocity at rest (PDV1) and under adenosine-induced hyperemia (PDV2) at baseline and 3-month follow-up.

RESULTS

Eight of 14 (57.1%) patients showed an impaired baseline CFR (PDV2/PDV1 < 2). These patients were characterized by higher levels of cardiac troponin T (0.55 ± 0.39 vs 0.18 ± 0.08; P = 0.008) and larger areas of LGE on CMR. At 3-month follow-up, CFR was normal in all patients.

CONCLUSION

A reversibly impaired coronary microcirculation is a frequent finding in acute myocarditis and is associated with markers of inflammation severity. Echocardiographic CFR measurement represents a feasible and safe method for its assessment.

Postoperative Assessment of Myocardial Function and Microcirculation in Patients with Acute Coronary Syndrome by Myocardial Contrast Echocardiography

BACKGROUND Postoperative myocardial function and microcirculation of acute coronary syndrome (ACS) was assessed by myocardial contrast echocardiography (MCE). MATERIAL AND METHODS Eighty-nine ACS patients treated with percutaneous coronary intervention (PCI) were detected by MCE and two-dimensional ultrasonography before and a month later after PCI respectively. Their myocardial perfusion was evaluated by myocardial contrast score (MSC) and contrast score index (CSI); cross-sectional area of microvessel (A), average myocardial microvascular impairment (β), and myocardial blood flow (MBF) were analyzed by cardiac ultrasound quantitative analysis (CUSQ), and fractional flow reserve (FFR) change was observed. Left ventricular ejection fraction (LVEF), left ventricular end-diastolic dimension (LVEDD), and left ventricular end-systolic dimension (LVESD) were observed; the index of microcirculatory resistance (IMR), FFR, and coronary flow reserve (CFR) were detected to evaluate coronary microcirculation. RESULTS None of the 89 patients experienced no-reflow. Patients with normal myocardial perfusion mostly had normal or slightly decreased ventricular wall motion after PCI. A month after the operation, there was an increase in A, β, MBF, LVEF, E/A, IMR, FFR, and CFR (all P<0.05), while LVEDD, LVESD, diastolic gallop A peak, E/Ea, E/Ea×S, and Tei decreased (all P<0.05). LVEF and IMR were in positive correlations with A. LVEF, IMR, FFR and CFR were positively correlated with b and MBF (both r>0, P<0.05), while E/Ea×Sa and Tei were negatively correlated with b and MBF (r<0, P<0.05). CONCLUSIONS MCE can safely assess post-PCI myocardial function and microcirculation of ASC.

Women with Stable Angina Pectoris and No Obstructive Coronary Artery Disease: Closer to a Diagnosis

A large proportion of women with chest pain have no obstructive coronary artery disease. Recent studies have demonstrated that these women continue to have symptoms and are at increased risk of cardiovascular morbidity and mortality. Coronary microvascular dysfunction (CMD) leads to an impairment of blood flow regulation to the myocardium and possible transient ischaemia. CMD is a disease entity with several pathophysiologic aspects and diagnostic modalities continue to be developed. However, due to the complexity of the disease, it remains elusive whether CMD is the explanation for the symptoms and the poor prognosis in women with angina and no obstructive coronary artery disease.

Coronary microvascular function and myocardial fibrosis in women with angina pectoris and no obstructive coronary artery disease: the iPOWER study

BACKGROUND

Even in absence of obstructive coronary artery disease women with angina pectoris have a poor prognosis possibly due to coronary microvascular disease. Coronary microvascular disease can be assessed by transthoracic Doppler echocardiography measuring coronary flow velocity reserve (CFVR) and by positron emission tomography measuring myocardial blood flow reserve (MBFR). Diffuse myocardial fibrosis can be assessed by cardiovascular magnetic resonance (CMR) T1 mapping. We hypothesized that coronary microvascular disease is associated with diffuse myocardial fibrosis.

METHODS

Women with angina, a clinically indicated coronary angiogram with <50 % stenosis and no diabetes were included. CFVR was measured using dipyridamole (0.84 mg/kg) and MBFR using adenosine (0.84 mg/kg). Focal fibrosis was assessed by 1.5 T CMR late gadolinium enhancement (0.1 mmol/kg) and diffuse myocardial fibrosis by T1 mapping using a modified Look-Locker pulse sequence measuring T1 and extracellular volume fraction (ECV).

RESULTS

CFVR and CMR were performed in 64 women, mean (SD) age 62.5 (8.3) years. MBFR was performed in a subgroup of 54 (84 %) of these women. Mean native T1 was 1023 (86) and ECV (%) was 33.7 (3.5); none had focal fibrosis. Median (IQR) CFVR was 2.3 (1.9; 2.7), 23 (36 %) had CFVR < 2 indicating coronary microvascular disease, and median MBFR was 2.7 (2.2; 3.0) and 19 (35 %) had a MBFR value below 2.5. No significant correlations were found between CFVR and ECV or native T1 (R 2  = 0.02; p = 0.27 and R 2  = 0.004; p = 0.61, respectively). There were also no correlations between MBFR and ECV or native T1 (R 2  = 0.1; p = 0.13 and R 2  = 0.004, p = 0.64, respectively). CFVR and MBFR were correlated to hypertension and heart rate.

CONCLUSION

In women with angina and no obstructive coronary artery disease we found no association between measures of coronary microvascular disease and myocardial fibrosis, suggesting that myocardial ischemia induced by coronary microvascular disease does not elicit myocardial fibrosis in this population. The examined parameters seem to provide independent information about myocardial and coronary disease.