Eosinophilic Coronary Periarteritis with Arterial Dissection: The Mast Cell Hypothesis

MINOCA biomarkers: Non-atherosclerotic aspects

Myocardial infarction in the absence of obstructive coronary artery disease (MINOCA) is an important subtype of myocardial infarction. Although comprising less than 50% stenosis in the main epicardial coronary arteries, it constitutes a severe health risk. A variety of approaches have been recommended, but definitive diagnosis remains elusive. In addition, the lack of a comprehensive understanding of underlying pathophysiology makes clinical management difficult and unpredictable. This review highlights ongoing efforts to identify relevant biomarkers in MINOCA to improve diagnosis, individualize treatment and better predict outcomes.

Pathophysiology of spontaneous coronary artery dissection: hematoma, not thrombus

Spontaneous coronary artery dissection (SCAD) accounts for 1.7%-4% of all acute coronary syndrome presentations, particularly among young women with an emerging awareness of its importance. The demarcation of acute SCAD from coronary atherothrombosis and the proper therapeutic approach still represents a major clinical challenge. Certain arteriopathies and triggers are related to SCAD, with high variability in their prevalence, and often, the cause remains unknown. The objective of this review is to provide contemporary knowledge of the pathophysiology of SCAD and possible therapeutic solutions.

Pregnancy-Associated Spontaneous Coronary Acute Dissection as a Cause of Sudden Cardiac Death-Autopsy Findings and Literature Review: Is COVID-19 Related?

Sudden cardiac death (SCD) is the leading cause of mortality globally (violent or non-violent), with few to no feasible remedies. The etiopathogenesis of SCD involves a complex and multilayered substrate in which dynamic factors interact with a preexistent cardiovascular pathology, which is often undiagnosed and untreated, leading to the rapid development of cardiac rhythm disorders and cardiac arrest. Cardiovascular disease is a rare but emerging factor in maternal mortality that can be justified by an upward trend in the mean age of pregnant individuals. Spontaneous coronary artery dissection (SCAD) is defined as a non-traumatic and non-iatrogenic separation of the coronary arterial wall by intramural hemorrhage with or without an intimal tear. The resulting intramural hematoma compresses the coronary arteries, reducing blood flow and causing myocardial ischemia. SCAD continues to be misdiagnosed, underdiagnosed, and managed as an atherosclerotic acute coronary syndrome, which may harm patients with SCAD. The latest research shows that individuals who have or have had coronavirus disease 2019 (COVID-19) may also present coagulation abnormalities, so infection with COVID-19 during pregnancy can increase this hypercoagulable condition, thus increasing the risk of SCAD and SCD. This present study reports two cases over 35 years, one being infected with SARS-COV2 one month before the event and the other being tested positive during admission, both asymptomatic, who were declared healthy on periodic clinical evaluations, with pregnancies over 35 weeks, with normal fetal development, which suddenly caused chest pain, dyspnea, and loss of consciousness, required emergency c-sections, and died suddenly after they were performed. In both cases, the cause of death was SCAD on the anterior-descending artery. In both cases, emergency percutaneous coronary intervention was performed. The second part of the study represents a literature overview of SCAD during COVID-19. In addition to pregnancy hormonal changes, other potential hormone-mediated SCAD triggers are still under discussion.

Spontaneous coronary artery dissection in a patient with recent COVID-19 infection: A case report

We report a spontaneous coronary artery dissection (SCAD) case in a lady with a history of recent COVID-19 and without any known predisposing factors. We also highlight the value of CMR as a noninvasive tool for tissue characterization, which can also be more applicable during the COVID-19 pandemic.

The presence of thrombus in spontaneous coronary artery dissection: A systematic review of autopsy findings

Background

Spontaneous coronary artery dissection (SCAD) is an important cause of acute coronary syndrome in young women. There is no consensus on optimal treatment, though a conservative approach including antiplatelet agents is commonly used. We hypothesized that most cases of SCAD would not demonstrate true lumen thrombus in the dissected artery, suggesting that anti-platelet agents might not have a role in the treatment of SCAD.

Methods

We conducted a systematic review of the published literature through March 2022 to identify pathology images from individuals who died of SCAD. The images were independently reviewed by a pathologist to assess for the presence of thrombus and inflammatory cells.

Results

We identified 40 cases from 34 publications with available pathology images and found only one case of true lumen thrombus. Additionally, we found that 53% of cases involved eosinophilic inflammation.

Conclusion

The role of antiplatelet agents in the treatment of SCAD should be re-evaluated. Further studies are needed to better understand the significance and treatment implications of eosinophilic inflammation.

Vascular histopathology and connective tissue ultrastructure in spontaneous coronary artery dissection: pathophysiological and clinical implications

Aims 

Spontaneous coronary artery dissection (SCAD) is a cause of acute coronary syndromes and in rare cases sudden cardiac death (SCD). Connective tissue abnormalities, coronary inflammation, increased coronary vasa vasorum (VV) density, and coronary fibromuscular dysplasia have all been implicated in the pathophysiology of SCAD but have not previously been systematically assessed. We designed a study to investigate the coronary histological and dermal collagen ultrastructural findings in SCAD.

Methods and results

Thirty-six autopsy SCAD cases were compared with 359 SCAD survivors. Coronary and myocardial histology and immunohistochemistry were undertaken. Transmission electron microscopy (TEM) of dermal extracellular matrix (ECM) components of n = 31 SCAD survivors and n = 16 healthy volunteers were compared. Autopsy cases were more likely male (19% vs. 5%; P = 0.0004) with greater proximal left coronary involvement (56% vs. 18%; P < 0.0001) compared to SCAD survivors. N = 24 (66%) of cases showed no myocardial infarction on macro- or microscopic examination consistent with arrhythmogenic death. There was significantly (P < 0.001) higher inflammation in cases with delayed-onset death vs. sudden death and significantly more inflammation surrounding the dissected vs. non-dissected vessel segments. N = 17 (47%) cases showed limited intimal fibro-elastic thickening but no features of fibromuscular dysplasia and no endothelial or internal elastic lamina abnormalities. There were no differences in VV density between SCAD and control cases. TEM revealed no general ultrastructural differences in ECM components or markers of fibroblast metabolic activity.

Conclusions 

Assessment of SCD requires careful exclusion of SCAD, particularly in cases without myocardial necrosis. Peri-coronary inflammation in SCAD is distinct from vasculitides and likely a reaction to, rather than a cause for SCAD. Coronary fibromuscular dysplasia or increased VV density does not appear pathophysiologically important. Dermal connective tissue changes are not common in SCAD survivors.

Spontaneous coronary artery dissection: Overview of pathophysiology

The growing use of imaging examinations has led to increased detection of spontaneous coronary artery dissection (SCAD) as a non-atherosclerotic cause of acute coronary syndrome (ACS). Since a greater awareness of pathophysiologic mechanisms has relevant implications in clinical practice, we aim to provide an update to current knowledge of SCAD pathophysiology. We discuss the most common conditions associated with SCAD, including predisposing factors and triggers, and focus on potential mechanisms leading to SCAD development. Furthermore, we report the main genetic research findings that have shed further light on SCAD pathophysiology. Finally, we summarize practical considerations in SCAD management based on pathophysiologic insights.

Ventricular Arrhythmias in Patients with Spontaneous Coronary Artery Dissection: Findings from the Gulf Spontaneous Coronary Artery Dissection (Gulf SCAD) Registry

BACKGROUND

Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of acute coronary syndrome in young women, with a wide clinical spectrum of severity. Ventricular arrhythmia (VA) can occur and worsen prognosis. The current study compared in-hospital and follow-up adverse cardiovascular events in patients with and without VA at presentation.

METHODS

Eighty-three cases of SCAD were collected retrospectively from 4 Gulf countries (KSA, UAE, Kuwait, and Bahrain) during the period from January 2011 to December 2017. We divided the patients into 2 groups: those with and without VA at presentation. VA was defined as ventricular tachycardia and/or ventricular fibrillation. In-hospital (recurrent VA, cardiogenic shock, death, implantable cardioverter-defibrillator placement, dissection extension) and follow-up (MI, de novo SCAD, death, spontaneous superior mesenteric artery dissection) events were compared among the 2 groups.

RESULTS

The median age of patients in the study was 44 (37-55) years. Forty-two (51%) were women. VA occurred in 10 (12%) patients in the first 24-hour of hospitalization, and 5 (50%) of those patients had recurrent in-hospital VA. Among those with recurrent VA, 1 died during hospitalization and 1 died within the first year following hospital discharge.

CONCLUSIONS

In-hospital adverse cardiovascular events were significantly more frequent for patients with SCAD who presented with VA. However, follow-up events were not statistically significant between those with and without VA at presentation.

Fatal eosinophilic coronary periarteritis leads to dissection in a young patient: A case report

Eosinophilic coronary periarteritis (ECPA) is a poorly studied type of coronary arteritis. It causes myocardial ischemia and most cases are diagnosed at autopsy. We report the case of a 35-year-old woman who presented with sudden unexpected cardiac arrest and was brought to the emergency ward. Cardiopulmonary resuscitation was started by ambulance paramedic. On arrival, the patient was transferred to the catheterization laboratory due to sudden aborted cardiac death. The angiography was performed and dissection of the left main coronary artery, extended to the left anterior descending artery was detected. Pathological study confirmed ECPA. It appears that young and healthy patients with a history of intermittent vasospastic angina should be evaluated for ECPA. <Learning objective: Young and healthy patients with a history of intermittent Prinzmetal vasospastic angina should be evaluated for eosinophilic coronary periarteritis (ECPA) prior to sudden cardiac death. Since ECPA is an unexpected and life-threatening condition, developing a diagnostic tool amongst suspicious young and healthy patients is demanded. Positron emission tomography-computed tomography might be an interesting tool, since it can detect infiltrative cells in early stages of cardiac inflammatory disease.>.

Clinicopathological complexity in the application of the universal definition of myocardial infarction

A universal definition of myocardial infarction (UDMI) has been established, periodically updated, and refined over the past twenty years. The primary purpose of the UDMI is to bring uniformity and accuracy to clinical diagnosis. Herein, a review and analysis of the UDMI is presented with emphasis on clinicopathological correlation. Determination of the presence of myocardial injury is based on the detection of abnormal serum cardiac biomarkers, particularly cardiac troponin (cTn), and in the current fourth iteration of the UDMI, high sensitivity (hs)-cTn. Differentiation of myocardial infarction from other causes of myocardial injury requires the documentation of clinical evidence of myocardial ischemia. In this review, difficulties in applying the UDMI in actual practice are discussed, based on the experience and perspective of those of us who face these problems as part of our own practice of pathology. The complexity in application of the UDMI is highlighted by the presentation of five illustrative cases involving the differential diagnosis of myocardial injury and myocardial infarction due to atherothrombotic and nonatherothrombotic coronary artery disease. The cases include myocardial infarction due to severe coronary atherosclerosis, supply-demand mismatch, coronary artery dissection associated with an eosinophilic coronary periarteritis, and coronary thromboembolism, and a case with a differential diagnosis of myocarditis and myocardial infarction. These cases illustrate how pathological findings can contribute to more accurate application of the UDMI and how, when critically applied, the UDMI can be used to better characterize myocardial infarcts in clinical practice.

The Non-cardiomyocyte Cells of the Heart. Their Possible Roles in Exercise-Induced Cardiac Regeneration and Remodeling

The non-cardiomyocyte cellular microenvironment of the heart includes diverse types of cells of mesenchymal origin. During development, the majority of these cells derive from the epicardium, while a subset derives from the endothelium/endocardium and neural crest derived mesenchyme. This subset includes cardiac fibroblasts and telocytes, the latter of which are a controversial type of "connecting cell" that support resident cardiac progenitors in the postnatal heart. Smooth muscle cells, pericytes, and endothelial cells are also present, in addition to adipocytes, which accumulate as epicardial adipose connective tissue. Furthermore, the heart harbors many cells of hematopoietic origin, such as mast cells, macrophages, and other immune cell populations. Most of these control immune reactions and inflammation. All of the above-mentioned non-cardiomyocyte cells of the heart contribute to this organ's well-orchestrated physiology. These cells also contribute to regeneration as a result of injury or age, in addition to tissue remodeling triggered by chronic disease or increased physical activity (exercise-induced cardiac growth). These processes in the heart, the most important vital organ in the human body, are not only fascinating from a scientific standpoint, but they are also clinically important. It is well-known that regular exercise can help prevent many cardiovascular diseases. However, the precise mechanisms underpinning myocardial remodeling triggered by physical activity are still unknown. Surprisingly, exercise-induced adaptation mechanisms are often identical or very similar to tissue remodeling caused by pathological conditions, such as hypertension, cardiac hypertrophy, and cardiac fibrosis. This review provides a summary of our current knowledge regarding the cardiac cellular microenvironment, focusing on the clinical applications this information to the study of heart remodeling during regular physical exercise.

Spontaneous Coronary Artery Dissection: Current State of the Science: A Scientific Statement From the American Heart Association

Spontaneous coronary artery dissection (SCAD) has emerged as an important cause of acute coronary syndrome, myocardial infarction, and sudden death, particularly among young women and individuals with few conventional atherosclerotic risk factors. Patient-initiated research has spurred increased awareness of SCAD, and improved diagnostic capabilities and findings from large case series have led to changes in approaches to initial and long-term management and increasing evidence that SCAD not only is more common than previously believed but also must be evaluated and treated differently from atherosclerotic myocardial infarction. High rates of recurrent SCAD; its association with female sex, pregnancy, and physical and emotional stress triggers; and concurrent systemic arteriopathies, particularly fibromuscular dysplasia, highlight the differences in clinical characteristics of SCAD compared with atherosclerotic disease. Recent insights into the causes of, clinical course of, treatment options for, outcomes of, and associated conditions of SCAD and the many persistent knowledge gaps are presented.

Protective Role of Mast Cells in Primary Systemic Vasculitis: A Perspective

Mast cells are important cells of the immune system. Although traditionally considered as key players in allergic and hypersensitivity reactions, emerging evidence suggests that mast cells have many complex roles in vascular disease. These include regulation of vasodilation, angiogenesis, activation of matrix metalloproteinases, apoptosis of smooth muscle cells, and activation of the renin angiotensin system. Mast cells are also known to play an immunomodulatory role via modulation of regulatory T-cell (Treg), macrophage and endothelial cell functions. This dual role of the mast cells is evident in myeloperoxidase anti-neutrophil cytoplasmic antibodies-mouse model of glomerulonephritis in which mast cell deficiency worsens glomerulonephritis, whereas inhibition of mast cell degranulation is effective in abrogating the development of glomerulonephritis. Our previous work demonstrated that mast cell degranulation inhibits lipopolysaccharide-induced interleukin 6 (IL-6) production in mice. This effect was not seen in histamine-1-receptor knockout (H1R^-/-) mice suggesting a role for histamine in IL-6 homeostasis. In addition, mast cell degranulation-mediated decrease in IL-6 production was associated with an upregulation of suppressor of cytokine signaling-1 protein in the aorta. We propose that mast cells regulate large artery inflammation through T-cells, shifting a primarily Th1 and Th17 toward a Th2 response and leading to enhanced IL-10 production, activation Treg cells, and the inhibition of macrophage functions.