Myocardial infarction with non-obstructive coronary arteries: A comprehensive review and future research directions

Predicting structure-targeted food bioactive compounds for middle-aged and elderly Asians with myocardial infarction: insights from genetic variations and bioinformatics-integrated deep learning analysis

Myocardial infarction (MI) is a significant global health issue. Despite the advances in genome-wide association studies, a complete genetic and molecular understanding of MI is elusive and needs to be fully explored. This study aimed to elucidate the genetic framework of MI and explore the potential health benefits of natural compounds (NCs). The genetic architecture of MI was explored using data from the Korean Genome and Epidemiology Study. We pinpointed crucial protein-coding genes related to MI by multi-marker analysis of genomic annotation for gene-based analysis. The bioinformatics-integrated deep neural analysis of NCs (BioDeepNat), a novel disease discovery application, was utilized to assess the influence of NCs on MI-related target proteins and validated with molecular docking analysis. The BioDeepNat application revealed significant NCs on MI-related target proteins, such as E-resveratrol, epicatechin 3-gallate, and kaempferol. The E3 region of RNF213 protein with a point mutation (Arg4810Lys) had different binding energies with NCs, such as ursolic acid and olean-12-en-28-oic acid, compared to the wild type. However, ginsenosides, eleutheroside, oleanolic acid, and hederagenin showed similar binding energies to wild and mutated types of RNF213 protein. The predicted NCs were primarily sourced from foods such as common grapes and teas. Aromatic hydrocarbons are frequently observed as the prevalent functional groups with high binding affinity for NCs in a molecular docking analysis. In conclusion, the proteins encoded by these genes identified by gene-based analysis interacted with several NCs with health promotion found in day-to-day foods, particularly E-resveratrol and kaempferol. This understanding offers promising directions for precision nutrition strategies in MI.

Role of Lipoprotein Ratios and Remnant Cholesterol in Patients with Myocardial Infarction with Non-Obstructive Coronary Arteries (MINOCA)

BACKGROUND

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a clinical situation characterized by evidence of acute myocardial infarction (AMI)-according to the Fourth Universal Definition of Myocardial Infarction-with normal or near-normal coronary arteries on angiographic study (stenosis < 50%). This condition is extremely variable in etiology, pathogenic mechanisms, clinical manifestations, prognosis and consequently therapeutic approach.

OBJECTIVE

The objective of the study was the evaluation of remnant cholesterol (RC), monocyte/high-density lipoprotein cholesterol ratio (MHR), platelet/lymphocyte ratio (PLR) and various lipoprotein ratios in patients with MINOCA in order to establish their validity as predictors of this event.

MATERIALS AND METHODS

We included 114 patients hospitalized in the Intensive Coronary Care Unit (ICCU) and Hospital Wards of our Hospital Center from 2015 to 2019 who received a diagnosis of MINOCA compared to a control group of 110 patients without previous cardiovascular events. RC was calculated with the following formula: RC = total cholesterol (TC) - HDL-C - LDL-C. MHR was calculated by dividing the monocyte count in peripheral blood by high-density lipoprotein cholesterol (HDL-C) levels; PLR was obtained by dividing platelet count by lymphocyte count. We also calculated various lipoprotein ratios, like total cholesterol/high-density lipoprotein cholesterol (TC/HDL-C), low-density lipoprotein cholesterol/high-density lipoprotein cholesterol (LDL-C/HDL-C), triglycerides/high-density lipoprotein cholesterol (TG/HDL-C), and non-high-density lipoprotein cholesterol/high-density lipoprotein cholesterol (non-HDL-C/HDL-C) ratios.

RESULTS

The MINOCA group had higher mean levels of RC (21.3 ± 10.6 vs. 13.2 ± 7.7 mg/dL), MHR (23 ± 0.009 vs. 18.5± 8.3) and PLR (179.8 ± 246.1 vs. 135 ± 64.7) than the control group. Only the mean values of all calculated lipoprotein ratios were lower in MINOCA patients. Statistical significance was achieved only in the RC evaluation.

CONCLUSIONS

Higher levels of RC and MHR were found in patients with MINOCA. We also observed higher levels of PLR than in the control group. Only various lipoprotein ratios were lower, but this could reflect the extreme heterogeneity underlying the pathogenic mechanisms of MINOCA. In patients who receive a diagnosis of MINOCA with a baseline alteration of the lipid profile and higher levels of cholesterol at admission as well, the evaluation of these parameters could play an important role, providing more detailed information about their cardiometabolic risk.

Cardiac Magnetic Resonance Imaging as a Risk Stratification Tool in COVID-19 Myocarditis

The aim of this retrospective study was to identify myocardial injury after COVID-19 inflammation and explore whether myocardial damage could be a possible cause of the persistent symptoms following COVID-19 infection in previously healthy individuals. This study included 139 patients who were enrolled between January and June 2021, with a mean age of 46.7 ± 15.2 years, of whom 68 were men and 71 were women without known cardiac or pulmonary diseases. All patients underwent clinical work-up, laboratory analysis, cardiac ultrasound, and CMR on a 1.5 T scanner using a recommended protocol for morphological and functional assessment before and after contrast media application with multi-parametric sequences. In 39% of patients, late gadolinium enhancement (LGE) was found as a sign of myocarditis. Fibrinogen was statistically significantly higher in patients with LGE than in those without LGE (4.3 ± 0.23 vs. 3.2 ± 0.14 g/L, p < 0.05, respectively), as well as D-dimer (1.8 ± 0.3 vs. 0.8 ± 0.1 mg/L FEU). Also, troponin was statistically significantly higher in patients with myocardial LGE (13.1 ± 0.4 ng/L) compared to those with normal myocardium (4.9 ± 0.3 ng/L, p < 0.001). We demonstrated chest pain, fatigue, and elevated troponin to be independent predictors for LGE. Septal LGE was shown to be a predictor for arrhythmias. The use of CMR is a potential risk stratification tool in evaluating outcomes following COVID-19 myocarditis.

MINOCA and INOCA: Role in Heart Failure

PURPOSE OF REVIEW

Infarction (MINOCA) and ischaemia (INOCA) with non-obstructive coronary disease are recent non-conventional presentations of coronary syndromes that are increasingly recognised in the clinical arena, particularly with the availability of new cardiovascular imaging techniques. Both are related to heart failure (HF). MINOCA is not associated with benign outcomes, and HF is among the most prevalent events. Regarding INOCA, microvascular dysfunction has also been found to associate with HF, particularly with preserved ejection fraction (HFpEF).

RECENT FINDINGS

Regardless of the several aetiologies underlying HF in MINOCA, it is likely related to LV dysfunction, where secondary prevention is not yet clearly established. Regarding INOCA, coronary microvascular ischaemia has been associated to endothelial dysfunction leading ultimately to diastolic dysfunction and HFpEF. MINOCA and INOCA are clearly related to HF. In both, there is a lack of studies on the identification of the risk factors for HF, diagnostic workup and, importantly, the appropriate primary and secondary prevention strategies.

Non-ST-segment elevation myocardial infarction with non-obstructive coronary arteries due to a type-A thymoma: A case report

Introduction

Myocardial infarction with non-obstructive coronary arteries (MINOCA) has become an increasingly recognized subgroup in patients with acute myocardial infarction, with a recent cohort study reporting a prevalence of 8.8%. This report describes a patient who presented with non-ST-segment elevation myocardial infarction (NSTEMI) due to an incidental anterior mediastinal mass.

Case presentation

An 80-year-old woman presented to our emergency department with a chief complaint of progressive shortness of breath associated with retrosternal chest pain for one day duration. Computed tomography (CT) angiogram of the chest was conducted, which revealed an anterior mediastinal mass. Upon admission, the patient developed an acute episode of recurrent severe chest pain, which was diagnosed as an NSTEMI. Emergent cardiac catheterization was performed because of unstable vital signs; however, the results showed no evidence of atherosclerotic changes in the major coronary arteries, compatible with the diagnosis of MINOCA. The mediastinal mass was later confirmed to be a type A thymoma on CT-guided biopsy.

Conclusion

Myocardial infarction in patent coronary arteries due to an anterior mediastinal mass is rare. Further studies are needed to standardize the diagnosis and management protocols for the potential etiologies of MINOCA.

Case report: A rare manifestation of vasospasm induced myocardial infarction with ST-segment elevation in a young male patient

Background

Minority of acute myocardial infarctions (MI) are caused by a non-atherosclerotic occlusion of the coronary artery. We present a case report, where MI with ST-segment elevation was provoked by a vasospasm, which is a rare aetiological finding.

Case presentation

27-year-old male patient presented to the emergency department because of a sudden onset chest pain radiating to the left arm. The patient underwent percutaneous coronary intervention (PCI) to the right coronary artery (RCA) 3 months ago due to inferior wall MI, however, chest pain episodes kept on recurring at night throughout the whole period after the intervention. During current admission, initial electrocardiogram (ECG) demonstrated ST-segment elevation in leads II, III and aVF. Coronary angiogram revealed diffuse severe narrowing of the right coronary artery, which was relieved with intracoronary administration of nitrates and verapamil. After coronary angiogram patient was given oral long-acting nitrates and verapamil, however, during the following days nocturnal chest pain episodes reoccurred. It was decided to swap verapamil to diltiazem, which led to complete cessation of angina episodes. The patient was discharged in stable condition and symptom free. It was suspected that the first MI was of vasospastic origin, which likely led to unnecessary stenting.

Conclusions

This clinical case has demonstrated the challenges clinician could face in order to correctly diagnose vasospasm-induced MI because of its rare occurrence and highly variable presentation. We strongly suggest using intracoronary nitroglycerine during coronary angiography as a standard practice to avoid a potential diagnostic error and unnecessary stenting. Although, in some cases the reason behind coronary artery spasm (CAS) remains unclear, medical treatment can be very effective for CAS prevention.

Is Takotsubo cardiomyopathy still looking for its own nosological identity?

Despite several efforts to provide a proper nosological framework for Takotsubo cardiomyopathy (TCM), this remains an unresolved matter in clinical practice. Several clinical, pathophysiologic and histologic findings support the conceivable hypothesis that TCM could be defined as a unique pathologic entity, rather than a distinct subset of myocardial infarction with non-obstructive coronary arteries. Further investigations are needed in order to define TCM with the most appropriate disease taxonomy.

Cellular Mechanisms of Coronary Artery Spasm

Coronary artery spasm (CAS) is a reversible phenomenon caused by spontaneous excessive vascular smooth muscle contractility and vascular wall hypertonicity, which results in partial or complete closure of the lumen of normal or atherosclerotic coronary arteries. The clinical picture of CAS includes chest discomfort which is similar in quality to that of stable effort angina. Mechanisms underlying the development of CAS are still unclear. CAS certainly is a multifactorial disease. In this review, we paid attention to the role of the main pathophysiologic mechanisms in CAS: endothelial dysfunction, chronic inflammation, oxidative stress, smooth muscle hypercontractility, atherosclerosis and thrombosis, and mutations leading to deficient aldehyde dehydrogenase 2 (ALDH2) activity. These findings might shed novel insight on the underlying mechanisms and identify potential diagnostic and therapeutic targets for cardiovascular diseases in the future.

[Thromboembolic mask of severe lymphocytic myopericarditis: possibilities of clinical and morphological diagnostics and complex treatment]

This report presents a clinical case of a 57-year-old female patient who was admitted for dyspnea, productive cough, reduced left ventricular (LV) systolic function, and who had previously undergone thoracocentesis for significant pleural effusion. This case is a unique combination of lymphocytic myocarditis and massive intracardiac and ileo-caval thrombosis. Morphological verification of the diagnosis, that was necessary prior to the administration of immunosuppressive therapy due to the prothrombogenic effect of glucocorticoids, provided a justification for a basis therapy for myocarditis, which significantly improved the patient's condition.

Coronary Artery Ectasia in the Pathophysiology of Myocardial Infarction With Nonobstructive Coronary Arteries

Coronary artery ectasia (CAE) is associated with an increased risk for acute myocardial infarction (AMI). A significant proportion of patients with AMI have no obstructive coronary artery disease (CAD), however, the underlying mechanism of myocardial infarction with nonobstructive coronary arteries (MINOCA) is poorly understood. Therefore, the present study aimed to investigate whether CAE has a role in the pathogenesis of MINOCA. A total of 1,284 patients who were admitted with a diagnosis of non-ST-segment elevation myocardial infarction were included in the study. Patients were divided into 2 groups according to the presence or absence of obstructive CAD (≥50% stenosis). Patients without obstructive CAD (MINOCA group) and patients with obstructive CAD (no-MINOCA group) were compared regarding the frequency of CAE. Additionally, the association between CAE and MINOCA was investigated. In the study participants, 101 patients (7.9%) were diagnosed with MINOCA, whereas 1,183 (92.1%) had AMI with obstructive CAD. Importantly, the frequency of patients with CAE was significantly higher in patients with MINOCA compared with those with obstructive CAD (22.8% vs 3.5%, p <0.001). Moreover, CAE was observed in 64 patients (4.9%). The frequency of MINOCA was found to be significantly higher in patients with CAE compared with patients without CAE (35.9% vs 6.4%, p <0.001). Furthermore, multivariate analysis demonstrated that the presence of CAE was an independent predictor of MINOCA in patients presented with a diagnosis of non-ST-segment elevation myocardial infarction (odds ratio 1.812, 95% confidence interval 1.376 to 2.581, p <0.001). In conclusion, CAE may be considered as a risk factor for MINOCA and may have a role in the pathophysiology of MINOCA.

Clinical presentation and management of myocardial infarction with nonobstructive coronary arteries (MINOCA): A literature review

Myocardial Infarction with Nonobstructive Coronary Arteries (MINOCA), as the name implies, is an acute myocardial infarction (MI) in the absence of significant coronary artery obstruction. Diagnosis and management of such cases have been challenging. There are many etiologies of MINOCA including coronary artery spasm, coronary microvascular dysfunction, plaque disruption, spontaneous coronary thrombosis or emboli, spontaneous coronary artery dissection, or cardiomyopathies. In this paper, the pathophysiology, diagnostic work-up, and clinical management for each subtype are described, and an overarching approach on how to evaluate and manage a patient presenting with MINOCA.

MINOCA: a heterogenous group of conditions associated with myocardial damage

Myocardial infarction with non-obstructive coronary arteries (MINOCA) was first described over 80 years ago. The term has been widely and inconsistently used in clinical practice, influencing various aspects of disease classification, investigation and management. MINOCA encompasses a heterogenous group of conditions that include both atherosclerotic and non-atherosclerotic disease resulting in myocardial damage that is not due to obstructive coronary artery disease. In many ways, it is a term that describes a moment in the diagnostic pathway of the patient and is arguably not a diagnosis. Central to the definition is also the distinction between myocardial infarction and injury. The universal definition of myocardial infarction distinguishes acute myocardial infarction, including those with MINOCA, from other causes of myocardial injury by the presence of clinical evidence of ischaemia. However, these ischaemic features are often non-specific causing diagnostic confusion, and can create difficulties for patient management and follow-up. The purpose of this review is to summarise our current understanding of MINOCA and highlight important issues relating to the diagnosis, investigation and management of patients with MINOCA.

Intracoronary optical coherence tomography: state of the art and future directions

Optical coherence tomography (OCT) has been increasingly utilised to guide percutaneous coronary intervention (PCI). Despite the diagnostic utility of OCT, facilitated by its high resolution, the impact of intracoronary OCT on clinical practice has thus far been limited. Difficulty in transitioning from intravascular ultrasound (IVUS), complex image interpretation, lack of a standardised algorithm for PCI guidance, and paucity of data from prospective clinical trials have contributed to the modest adoption. Herein, we provide a comprehensive up-do-date overview on the utility of OCT in coronary artery disease, including technical details, device set-up, simplified OCT image interpretation, recognition of the imaging artefacts, and an algorithmic approach for using OCT in PCI guidance. We discuss the utility of OCT in acute coronary syndromes, provide a summary of the clinical trial data, list the work in progress, and discuss the future directions.

Cannabinoids and myocardial ischemia: Novel insights, updated mechanisms, and implications for myocardial infarction

Cannabis is the most widely trafficked and abused illicit drug due to its calming psychoactive properties. It has been increasingly recognized as having potential health benefits and relatively less adverse health effects as compared to other illicit drugs; however, growing evidence clearly indicates that cannabis is associated with considerable adverse cardiovascular events. Recent studies have linked cannabis use to myocardial infarction (MI); yet, very little is known about the underlying mechanisms. A MI is a cardiovascular disease characterized by a mismatch in the oxygen supply and demand of the heart, resulting in ischemia and subsequent necrosis of the myocardium. Since cannabis is increasingly being considered a risk factor for MI, there is a growing need for better appreciating its potential health benefits and consequences. Here, we discuss the cellular mechanisms of cannabis that lead to an increased risk of MI. We provide a thorough and critical analysis of cannabinoids' actions, which include modulation of adipocyte biology, regional fat distribution, and atherosclerosis, as well as precipitation of hemodynamic stressors relevant in the setting of a MI. By critically dissecting the modulation of signaling pathways in multiple cell types, this paper highlights the mechanisms through which cannabis may trigger life-threatening cardiovascular events. This then provides a framework for future pharmacological studies which can identify targets or develop drugs that modulate cannabis' effects on the cardiovascular system as well as other organ systems. Cannabis' impact on the autonomic outflow, vascular smooth muscle cells, myocardium, cortisol levels and other hemodynamic changes are also mechanistically reviewed.

Biotherapeutic-loaded injectable hydrogels as a synergistic strategy to support myocardial repair after myocardial infarction

Myocardial infarction (MI) has been considered as the leading cause of cardiovascular-related deaths worldwide. Although traditional therapeutic agents including various bioactive species such as growth factors, stem cells, and nucleic acids have demonstrated somewhat usefulness for the restoration of cardiac functions, the therapeutic efficiency remains unsatisfactory most likely due to the off-target-associated side effects and low localized retention of the used therapeutic agents in the infarcted myocardium, which constitutes a substantial barrier for the effective treatment of MI. Injectable hydrogels are regarded as a minimally invasive technology that can overcome the clinical and surgical limitations of traditional stenting by a modulated sol-gel transition and localized transport of a variety of encapsulated cargoes, leading to enhanced therapeutic efficiency and improved patient comfort and compliance. However, the design of injectable hydrogels for myocardial repair and the mechanism of action of bioactive substance-loaded hydrogels for MI repair remain unclear. To elucidate these points, we summarized the recent progresses made on the use of injectable hydrogels for encapsulation of various therapeutic substances for MI treatment with an emphasis on the mechanism of action of hydrogel systems for myocardial repair. Specifically, the pathogenesis of MI and the rational design of injectable hydrogels for myocardial repair were presented. Next, the mechanisms of various biotherapeutic substance-loaded injectable hydrogels for myocardial repair was discussed. Finally, the potential challenges and future prospects for the use of injectable hydrogels for MI treatment were proposed for the purpose of drawing theoretical guidance on the development of novel therapeutic strategies for efficient treatment of MI.

Recent insights into pathophysiology and management of mechanical complications of myocardial infarction

PURPOSE OF REVIEW

Mechanical complications of myocardial infarction are a group of postischemic events and include papillary muscle rupture resulting in ischemic mitral regurgitation, ventricular septal defect, left ventricle free wall rupture, pseudoaneurysm, and true aneurysm. Advances made in management strategies, such as the institution of 'Code STEMI' and percutaneous interventions, have lowered the incidence of these complications. However, their presentation is still associated with increased morbidity and mortality. Early diagnosis and appropriate management is crucial for facilitating better clinical outcomes.

RECENT FINDINGS

Although the exact timing of a curative intervention is not known, emerging percutaneous and transcatheter approaches and improving mechanical circulatory support (MCS) devices have greatly enhanced our ability to manage and treat some of the complications postinfarct.

SUMMARY

Although the incidence of mechanical complications of myocardial infarction has decreased over the past few decades, these complications are still associated with high rates of morbidity and mortality. The combination of early and accurate diagnosis and subsequent appropriate management are imperative for optimizing clinical outcomes. Although more randomized clinical trials are needed, mechanical circulatory support devices and emerging therapeutic strategies can be offered to carefully selected patients.

Myocardial Infarction with Nonobstructive Coronary Arteries: A Diagnostic Challenge

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is a significant cause of cardiovascular morbidity, especially among non-white women younger than 55 years. It is a working diagnosis that warrants further investigation due to its varied underlying pathophysiologic mechanisms. Investigations may be hampered by unavailability of testing modalities, cost, and the expertise to carry out the tests, as they are highly specialized. Clinical history is therefore important, especially in developing countries, to predict potential causes and institute empirical treatment without the luxury of tests. Some physicians are also unaware of this phenomenon and may dismiss symptoms as functional when a coronary angiogram shows nonobstructed coronary arteries, potentially resulting in patients suffering symptoms for longer and incurring extra cost. Most importantly, it leaves them at risk of major adverse cardiovascular events. This article presents a patient with atrial fibrillation who was diagnosed with MINOCA and highlights the diagnostic challenges in evaluating MINOCA.

Clinical and electrocardiographic features of patients with myocardial infarction with non-obstructive coronary artery disease (MINOCA)

AIMS

Myocardial infarction with non-obstructive coronary artery disease (MINOCA) is often an underdiagnosed and undertreated condition. This study aimed to evaluate clinical and ECG characteristics of MINOCA in a large cohort of patients admitted for acute coronary syndrome.

METHODS

All coronary angiograms performed at the University Heart Center in Zurich (Switzerland) between 2012 and 2016 were investigated. MINOCA was defined according to European Society of Cardiology guidelines and patients were divided into two groups, based on the presence or absence of coronary sclerosis at angiogram[nonobstructive coronary artery disease (noCAD) and normal coronary arteries (NCA)]), after exclusion of myocarditis and Takotsubo syndrome.

RESULTS

Out of 13 669 angiographic studies, 3695 were diagnosed with acute coronary syndrome; of these, 244 patients presented MINOCA (6.6%). Patients with noCAD were more likely to be older (67.9 vs. 59.2 years, P < 0.001) with higher prevalence of traditional cardiovascular risk factors (hypertension 64.1 vs. 41.2%, P = 0.002; diabetes 19.7 vs. 10.8%, P = 0.036; hypercholesterolemia 36.6 vs. 23.5%, P = 0.037). On surface ECG, anterior ST- segment elevation was more frequent in NCA patients (13.7 vs. 5.0%, P = 0.016). Secondary prevention therapy was significantly more prescribed in noCAD compared with NCA patients (acetylsalicylic acid 68.3 vs. 21.6%, P less than 0.001; statins 76.1 vs. 22.5%, P less than 0.001; angiotensin-converting enzyme inhibitor-AT1 blockers 51.4 vs. 31.3%, P = 0.006). One-year mortality was very low (0.4% for noCAD patients).

CONCLUSION

noCAD patients were older, with higher prevalence of cardiovascular risk factors and more frequently discharged with secondary prevention therapy. NCA patients presented more frequently anterior ST- segment elevation. Further diagnostic tests should be highly recommended to determine the underlying mechanism of MINOCA.

Myocardial infarction with non-obstructive coronary arteries (MINOCA): Intracoronary imaging-based diagnosis and management

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is defined by clinical evidence of myocardial infarction (MI) with normal or near-normal coronary arteries on angiography. This condition is present in about 5% to 25% of patients presenting with acute coronary syndromes. MINOCA is a working diagnosis. Current guidelines and consensus recommend identification of underlying causes of MINOCA in order to optimize treatment, improve prognosis, and promote prevention of recurrent myocardial infarction. An accurate evaluation of patient history, symptoms and use of invasive and non-invasive imaging should lead to identification of epicardial or microvascular causes of MINOCA and differentiation from non-ischemic myocardial injury due to both cardiac (e.g. myocarditis) and non-cardiac disease (e.g. pulmonary embolism). In this review, we highlight the role of coronary imaging in differential diagnosis of patients presenting with MINOCA. Intravascular ultrasound and optical coherence tomography are well known technologies used in different settings from acute to chronic coronary syndromes. In MINOCA patients, coronary imaging could help to identify pathological alterations of the epicardial vessels that are not visible by coronary angiography such as plaque disruption, coronary dissection, coronary thromboembolism, coronary spasm, and coronary artery disease in patients presenting with takotsubo syndrome. In future, the widespread use of these technologies, in the right clinical context, could lead to optimization and personalization of treatment, and to better prognosis of patients presenting with MINOCA.

Cardiac MRI in Patients with Acute Chest Pain

Acute chest pain is a common reason for visits to the emergency department. It is important to distinguish among the various causes of acute chest pain, because treatment and prognosis are substantially different among the various conditions. It is critical to exclude acute coronary syndrome (ACS), which is a major cause of hospitalization, death, and health care costs worldwide. Myocardial ischemia is defined as potential myocyte death secondary to an imbalance between oxygen supply and demand due to obstruction of an epicardial coronary artery. Unobstructed coronary artery disease can have cardiac causes (eg, myocarditis, myocardial infarction with nonobstructed coronary arteries, and Takotsubo cardiomyopathy), and noncardiac diseases can manifest with acute chest pain and increased serum cardiac biomarker levels. In the emergency department, cardiac MRI may aid in the identification of patients with non-ST-segment elevation myocardial infarction or unstable angina or ACS with unobstructed coronary artery disease, if the patient's clinical history is known to be atypical. Also, cardiac MRI is excellent for risk stratification of patients for adverse left ventricular remodeling or major adverse cardiac events. Cardiac MRI should be performed early in the course of the disease (<2 weeks after onset of symptoms). Steady-state free-precession T2-weighted MRI with late gadolinium enhancement is the mainstay of the cardiac MRI protocol. Further sequences can be used to analyze the different pathophysiologic subjacent mechanisms of the disease, such as microvascular obstruction or intramyocardial hemorrhage. Finally, cardiac MRI may provide several prognostic biomarkers that help in follow-up of these patients. Online supplemental material is available for this article. ^©RSNA, 2020.

Dual antiplatelet therapy in myocardial infarction with non-obstructive coronary artery disease - insights from a nationwide registry

INTRODUCTION AND OBJECTIVES

Dual antiplatelet therapy (DAPT) is a mainstay for myocardial infarction (MI) therapy. However, in patients with myocardial infarction with non-obstructive coronary artery disease (MINOCA), clear recommendations are lacking in the literature. This study aims to identify the cases in which DAPT is currently prescribed at discharge for MINOCA.

METHODS

The authors analyzed a cohort of patients from a multicenter national registry enrolling patients who suffered their first MI between 2010 and 2017, and underwent coronary angiography revealing absence of stenosis ≥50%. Individual antithrombotic therapy was identified. A logistic regression analysis was applied to search for predictors of DAPT.

RESULTS

From a total of 16 237 patients analyzed, 709 (4.4%) were categorized as MINOCA. Mean age was 64±13 years, 46.3% (n=409) were females. 390 (55.0%) of MINOCA patients were discharged on DAPT. Males (OR 1.67, CI 95 [1.05-2.38], p=0.027), active smokers (OR=1.82, CI 95 [1.05-3.16], p=0.033), previous percutaneous intervention (OR 3.18, CI 95 [1.48-6.81], p=0.003), ST elevation MI (OR 2.70, CI 95 [1.59-4.76], p<0.001) and sinus rhythm at admission (OR=3.94, CI 95 [2.07-7.48], p<0.001) were independent predictors of DAPT use.

CONCLUSION

In this nationwide registry, DAPT was prescribed at discharge in 55% of MINOCA patients. Beyond sinus rhythm, the variables presented as independent predictors for DAPT use identify subgroups of patients who are classified as more prone to thrombotic events. The issue of how to handle antithrombotic agents in MINOCA patients is a topic open for discussion.

Association Between Obstructive Sleep Apnea-Hypopnea Syndrome and Outcomes in Patients With Myocardial Infarction in the Absence of Obstructive Coronary Artery Disease

Background and Aims: Myocardial infarction in the absence of obstructive coronary artery disease (MINOCA) occurs in 5-10% of all patients with acute myocardial infarction. Obstructive sleep apnea-hypopnea syndrome (OSAHS) is linked to increased cardiovascular morbidity and mortality, but the relationship of OSAHS and outcomes in patients with MINOCA remains unknown. We aimed to evaluate the association between OSAHS and clinical outcomes in patients with MINOCA. Methods: Between January 2015 and December 2016, we carried out a consecutive cohort study of 583 patients with MINOCA and followed them up for 3 years. An apnea-hypopnea index of ≥ 15 events per hour recorded by polysomnography was defined as the diagnostic criterion for OSAHS. The primary end point was all-cause mortality, and the second end point was major adverse cardiovascular or cerebrovascular events (MACCE), a composite of cardiac death, non-fatal myocardial infarction, heart failure, cardiovascular-related rehospitalization, and stroke. Results: All-cause mortality happened in 69 patients and MACCE occurred in 113 patients during the 3-year follow-up. Kaplan-Meier survival curves indicated the significant relationship of OSAHS with all-cause mortality (log-rank P = 0.012) and MACCE (log-rank P = 0.002). Multivariate Cox regression analysis indicated OSAHS as an independent predictor of all-cause mortality and MACCE [adjusted hazard ratio: 1.706; 95% confidence interval (CI): 1.286-2.423; P = 0.008; and adjusted hazard ratio: 1.733; 95% CI: 1.201-2.389; P < 0.001; respectively], independent of age, sex, cardiovascular risk factors and discharge medications. Conclusions: OSAHS is independently associated with increased risk of all-cause mortality and MACCE in patients with MINOCA. Intervention and treatment should be considered to alleviate OSAHS-associated risk.

Diagnostic and Management Dilemmas in Women Presenting with Acute Coronary Syndromes

PURPOSE OF REVIEW

To summarize gender- and sex-specific differences in the presentation, diagnosis, management, and pathophysiology of women presenting with acute coronary syndrome (ACS).

RECENT FINDINGS

Sex differences exist in many aspects of ACS that impact the identification, treatment, and outcomes in women. There are delays in the initiation of care, under recognized diagnostic differences based on sex, and inconsistencies in the management of ACS in women compared with men, that ultimately impact outcomes. Additionally, women with ACS are more likely than men to present with non-obstructive coronary artery disease (CAD), which appears to be due to diverse underlying pathophysiology. Women with ACS face diagnostic and treatment dilemmas from time of symptom onset to hospital discharge. Under-recognition, under-diagnosis, and under-treatment ultimately result in poorer outcomes in women. Underlying pathophysiologic differences in women require additional testing to elucidate underlying etiologies.

High versus Low Mechanical Index Imaging Diagnostic Ultrasound in Patients with Myocardial Infarction: A Therapeutic Application Study

Background

High mechanical index impulse of ultrasound is used for diagnosis of microvascular coronary obstruction and the necrotic area, but an experimental model study suggested that it can restore microvascular and epicardial coronary flow. The purposes of the study were to test the safety and therapeutic efficacy of high acoustic energy diagnostic ultrasound in patients with ST-segment elevation myocardial infarction.

Material/Methods

Patients with ST-segment elevation myocardial infarction subjected to a low (n=199) or high (n=251) mechanical index ultrasound before and after percutaneous coronary interventions and echocardiographic parameters were evaluated. Coronary angiographies were performed for the assessment of culprit vessels. Thrombolysis in myocardial infarction flow grade 1 or 2 were considered as culprit vessels.

Results

Patients diagnosed through low acoustic energy ultrasound reported 235 infarct vessels and patients diagnosed through high acoustic energy ultrasound reported 300 infarct vessels. With respect to low acoustic energy, high acoustic energy reduced the number of culprit vessels at post-percutaneous coronary interventions at 48 hours before hospital discharge (P=0.015) and post-percutaneous coronary interventions at 1-month from the baseline interventions (P=0.043). Also, the maximum% ST-segment resolution and an ejection fraction of the left ventricle was increased and microvascular coronary obstruction in infarct vessels was decreased for both evaluation points. High acoustic energy could not affect heart rate (P=0.133) and oxygen saturation (P=0.079).

Conclusions

High acoustic energy ultrasound is a safe method for diagnosis of ST-segment elevation myocardial infarction and may have therapeutic applications.

Acute myocardial injury after administration of intravenous epinephrine for allergic reaction

Myocardial injury or infarction in the setting of anaphylaxis can be due to anaphylaxis itself, known as Kounis syndrome, or as a result of treatment with epinephrine. Myocardial ischemia caused by therapeutic doses of epinephrine in the setting of anaphylaxis is a rare event attributed to coronary artery vasospasm. A 41-year-old female with past medical history of recurrent costochondritis, chronic thrombocytopenia, and nonspecific palindromic rheumatism presented to the emergency department with perioral numbness, flushing and throat tightness after a meal containing fish and almonds. Intramuscular epinephrine was ordered but inadvertently administered intravenously, after which she developed sharp, substernal chest pain and palpitations. Electrocardiogram showed normal sinus rhythm with QT interval prolongation. Troponin peaked at 1.41 ng/mL. She was given 324 mg of aspirin in the emergency department. Transthoracic echocardiogram showed normal ejection fraction with lateral wall motion abnormality. We present a case of a patient with no significant risk factors for coronary artery disease who developed myocardial injury following inadvertent IV administration of a therapeutic dose of epinephrine for an anaphylactic-like reaction. The development of myocardial injury after epinephrine is rare, with only six reported cases in literature and just one after intravenous administration. This is the first described case of known myocardial injury without ST-T wave changes on electrocardiogram . The proposed mechanism is an alpha-1 receptor-mediated coronary vascular spasm resulting in myocardial ischemia. The aim of this case is to raise awareness of the potential for acute myocardial injury after inadvertent intravenous administration of epinephrine for anaphylaxis, even in patients with no known risk factors for coronary artery disease, as well as to demonstrate that this clinical scenario can present regardless of troponin elevation and without ST-T wave ECG changes.