Troponin-Positive Non-Obstructive Coronary Arteries and Myocardial Infarction with Non-Obstructive Coronary Arteries: Definition, Etiologies, and Role of CT and MR Imaging

MINOCA: A Working Diagnosis

Cases of patients presenting with myocardial infarction (MI) without angiographic obstructive CAD are not trivial and have significant prevalence. "The Fourth Universal Definition of MI" (4UDMI) published in 2018 introduced MI with non-obstructive coronary arteries (MINOCA). The new section was of great importance as it validated the diagnosis by defining its criteria and recognizing its presence in the community and the need for further investigation. Given the nature of the diagnosis of MINOCA, coronary angiography provides limited information about prognosis and risk stratification for future major adverse cardiovascular events (MACE). Thus, additional imaging to understand the underlying etiology of MINOCA in conjunction with a better understanding of prognostic factors is necessary to expand on the current guidelines and aid in screening for possible complications, risk of MACE, and all-cause mortality. Discerning the etiology of the presentation is crucial, and physiologic studies, as well as additional imaging, are an important part of this evaluation. These modalities include intravascular studies such as optical coherence tomography (OCT), intravascular ultrasound (IVUS), fractional flow reserve (FFR), and imaging in the form of cardiac CT (CCT) and cardiac MRI (CMR). This step is essential to target treatment regimens more efficiently. The purpose of promoting multiple imaging modalities beyond traditional angiography is to address the working MINOCA diagnosis, with the finality of identifying the specific ischemic pathophysiology. MINOCA has multiple causative mechanisms, making it a heterogeneous collection of etiologies, resulting in acute MI: atherosclerotic, and non-atherosclerotic. This literature revision demonstrates that MINOCA prevalence and mortality are not trivial, and the diagnosis affects quality of life. MINOCA presents a definitive risk of MACE without proper stratification and targeted medical therapy. Several prognostic factors of morbidity and mortality in MI-CAD patients have been identified to correlate with MINOCA patients, especially inflammatory markers. MINOCA is not an exclusion diagnosis but a working diagnosis for which further imaging studies should be performed.

Role of CT and MRI in Cardiac Emergencies

Current strategies for the evaluation of patients with chest pain have significantly changed thanks to the implemented potentiality of CT and MRI. The possible fatal consequences and high malpractice costs of missed acute coronary syndromes lead to unnecessary hospital admissions every year. CT provides consistent diagnostic support, mainly in suspected coronary disease in patients with a low or intermediate pre-test risk. Moreover, it can gain information in the case of cardiac involvement in pulmonary vascular obstructive disease. MRI, on the other hand, has a leading role in the condition of myocardial damage irrespective of the underlying inflammatory or stress related etiology. This article discusses how radiology techniques (CT and MRI) can impact the diagnostic workflow of the most common cardiac and vascular pathologies that are responsible for non-traumatic chest pain admissions to the Emergency Department.

Role of Coronary CT Angiography in the Evaluation of Acute Chest Pain and Suspected or Confirmed Acute Coronary Syndrome

Advances in CT technology have resulted in improved imaging of the coronary anatomy in patients with stable coronary artery disease, using coronary CT angiography (CCTA). Recent data suggest that CCTA may play a role in higher risk patients, such as those evaluated in the emergency room with acute chest pain. Data thus far support the use of CCTA in low-risk patients with acute chest pain. Recent literature suggests that CCTA may play a role in the risk stratification of selected intermediate-risk patients. In this review, the authors discuss the emerging role of CCTA in higher risk patients, such as those with suspected or confirmed acute coronary syndrome (ACS). The excellent accuracy of CCTA in detecting obstructive coronary artery disease in patients with ACS is detailed, along with a highlighting of the safety of using CCTA in this setting. The authors also discuss the role for CCTA atheromatous plaque characterization, which is being increasingly recognized as an important predictor of clinical outcomes.

The Value of Iterative Reconstruction of Algorithm-Based Coronary Artery Computed Tomography Imaging in the Diagnosis of Old Myocardial Infarction

The objective of this study was to compare the diagnostic value of computed tomography (CT) based on iterative reconstruction algorithm in old myocardial infarction (OMI), thereby providing theoretical guidance and practical basis for clinical treatment. In this study, in order to provide theoretical guidance and practical basis for the diagnosis and treatment of clinical OMI, 10 patients with OMI were selected and divided into two groups, with 5 patients in each group. In addition, an algebraic iterative reconstruction algorithm is constructed, which starts from the initial estimation value, compares, and corrects the estimation results and the measured results continuously until the error between the two results is less than the predetermined value. The experimental group was optimized by algebraic iterative reconstruction algorithm, and the control group was reconstructed by the hospital original method. The image quality parameters under different iteration times were analyzed and compared to obtain the optimal iteration times. The value of iterative reconstruction algorithm in clinical diagnosis was investigated by analyzing the time of drawing and the accuracy of diagnosis after drawing. Through the analysis and comparison of the image quality parameters of the patients from the experimental group, it was found that the image quality firstly increased with the increase in the number of iterations but decreased with the increase of the number of iterations after a certain number of iterations. The results showed that the optimal number of iterations was 13 times. The drawing time of the experimental group and the control group was 54.27 minutes and 117.87 minutes in turn, so the difference between the two groups was significant (P < 0.05). Besides, there was a statistically marked difference in the accuracy rate of the experimental group (93.33%) and the control group (73.33%) (P < 0.05). In conclusion, the time required for coronary artery CT imaging using algebraic iterative reconstruction algorithm was greatly reduced and the diagnostic accuracy was hugely improved. Therefore, the coronary artery CT imaging based on iterative reconstruction algorithm could make more effective use of medical resources and improve the diagnostic accuracy in the diagnosis of OMI.

Unraveling the Association Between Myocardial Infarction of Nonobstructive Coronary Arteries and Antiphospholipid Syndrome

The term "myocardial infarction with nonobstructive coronary arteries (MINOCA)" refers to a condition characterized by clinical signs and symptoms consistent with acute myocardial infarction (AMI) (as defined by the third universal definition of infarction) and coronary arteries that are angiographically normal or nearly normal. A prominent source of morbidity and mortality in patients with antiphospholipid syndrome (APS) is thrombotic events. To evaluate whether there is a relation between APS and MINOCA in this research, we did an extensive assessment of the existing research in this field. According to the data, APS was associated with microvascular thrombosis, aberrant lipid metabolism, hypertension, and abnormalities of the coagulation cascade, among other conditions. Based on the available data, we discovered evidence that suggests a relationship between MINOCA and APS patients. It is vital to raise awareness of this concern among the general public. Also required is the development and implementation of diagnostic and targeted treatment guidelines for patients with APS and MINOCA.

Review Article--Clinical Overview of Myocardial Infarction Without Obstructive Coronary Artey Disease (MINOCA)

The term myocardial infarction with non-obstructive coronary arteries (MINOCA) applies to patients who have clinical evidence of AMI but coronary angiography reveals no coronary obstructions and an alternative diagnosis is not possible. It is a heterogenous group of disease. Its prognosis, predictors of mortality and optimum management is unclear. In this review, we present a disease overview for MINOCA including the clinical features, adopted definitions, prevalence, diagnosis, treatment, and prognosis.

Current Role of Computed Tomography in the Evaluation of Acute Coronary Syndrome

This review article provides an overview regarding the role of computed tomography (CT) in the evaluation of acute chest pain (ACP) in the emergency department (ED), focusing on characteristic CT findings.

The role of coronary computed tomography angiography in evaluation of high troponin patients with narrow-complex supraventricular tachycardia

Aim:

The aim of this study was to investigate the relation of high-sensitive cardiac troponin T (hs-cTnT) elevation with characteristics of supraventricular tachycardia (SVT) episode (duration and maximum heart rate) and coronary computed tomography angiography (CCTA) findings in patients with SVT who presented to the emergency room with palpitation.

Methods:

This retrospective, single-center, noninvasive study included all patients aged between 18 years and 65 years who presented to the emergency department due to narrow-complex SVT and underwent CCTA to rule out coronary artery disease (CAD) due to elevation of hs-cTnT and reverted back to sinus rhythm after intravenous adenosine. The first, second, and the maximum hs-cTnT levels were obtained from the database. The patients were classified into normal coronaries, nonobstructive CAD, and obstructive CAD according to findings of the CCTA. The findings of the groups were compared.

Results:

Eighty-five patients were enrolled in the study. Of them, 21 (26%) patients were female. Sixty-three patients (74%) had normal coronary arteries as per CCTA results, whereas 22 patients (22%) had nonobstructive CAD and two patients (2%) had obstructive CAD. The groups did not differ statistically in respect to hs-cTnT measurements, duration of the arrhythmia, and maximum heart rate at SVT episode. There was no significant statistical correlation between hs-cTnT and the study parameters except the maximum heart rate.

Conclusion:

Cardiac troponins may increase in patients with paroxysmal SVT irrespective of the presence of coronary lesions, and the CCTA may not be an appropriate investigation in the differential diagnosis of paroxysmal SVT with elevated hs-cTnT.