Diagnosis of viral myocarditis by cardiac magnetic resonance and viral genome detection in peripheral blood

Myocardial Oedema as a Consequence of Viral Infection and Persistence-A Narrative Review with Focus on COVID-19 and Post COVID Sequelae

Microvascular integrity is a critical factor in myocardial fluid homeostasis. The subtle equilibrium between capillary filtration and lymphatic fluid removal is disturbed during pathological processes leading to inflammation, but also in hypoxia or due to alterations in vascular perfusion and coagulability. The degradation of the glycocalyx as the main component of the endothelial filtration barrier as well as pericyte disintegration results in the accumulation of interstitial and intracellular water. Moreover, lymphatic dysfunction evokes an increase in metabolic waste products, cytokines and inflammatory cells in the interstitial space contributing to myocardial oedema formation. This leads to myocardial stiffness and impaired contractility, eventually resulting in cardiomyocyte apoptosis, myocardial remodelling and fibrosis. The following article reviews pathophysiological inflammatory processes leading to myocardial oedema including myocarditis, ischaemia-reperfusion injury and viral infections with a special focus on the pathomechanisms evoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In addition, clinical implications including potential long-term effects due to viral persistence (long COVID), as well as treatment options, are discussed.

Patterns of cardiovascular magnetic resonance inflammation in acute myocarditis from South Asia and Middle East

Background

Cardiovascular magnetic resonance (CMR) is the test of choice for diagnosis and risk stratification of myocardial inflammation in acute viral myocarditis. The objective of this study was to assess patterns of CMR inflammation in a cohort of acute myocarditis patients from Northern Africa, Asia, and the Middle East using unsupervised machine learning.

Methods

A total of 169 racially and ethnically diverse adults (≥18 years of age) with CMR confirmed acute myocarditis were studied. The primary outcome was a combined clinical endpoint of cardiac death, arrhythmia, and dilated cardiomyopathy. Machine learning was used for exploratory analysis to identify patterns of CMR inflammation.

Results

Our cohort was diverse with 25% from Northern Africa, 33% from Southern Asia, and 28% from Western Asia/the Middle East. Twelve patients met the combined clinical endpoint – 3 had arrythmia, 8 had dilated cardiomyopathy, and 1 died. Patients who met the combined endpoint had increased anterior (p = 0.034) and septal (p = 0.042) late gadolinium enhancement (LGE). Multivariable logistic regression, adjusted for age, gender, and BMI, found that patients from Southern Asia (p = 0.041) and the Middle East (p = 0.043) were independently associated with lateral LGE. Unsupervised machine learning and factor analysis identified two distinct CMR patterns of inflammation, one with increased LGE and the other with increased myocardial T1/T2.

Conclusions

We found that anteroseptal inflammation is associated with worsened outcomes. Using machine learning, we identified two patterns of myocardial inflammation in acute myocarditis from CMR in a racially and ethnically diverse group of patients from Southern Asia, Northern Africa, and the Middle East.

Fulminant myocarditis: a comprehensive review from etiology to treatments and outcomes

Fulminant myocarditis (FM) is characterized by a rapid progressive decline in cardiac function and a high mortality rate. Since the first report of FM patients in the 1980s, several clinical trials and research studies have been published increasing our knowledge regarding FM. Currently, the diagnosis of FM depends on various techniques including electrocardiography, echocardiography, endomyocardial biopsy, and cardiac magnetic resonance. The development of mechanical circulation support (MCS) devices and progress in our understanding of the pathophysiological mechanisms underlying FM, treatment regimens have evolved from simple symptomatic treatment to a life support-based comprehensive treatment approach. The core mechanism underlying the development of FM is the occurrence of an inflammatory cytokine storm. This review provides a comprehensive account of the current understanding of FM pathophysiology and knowledge regarding its etiology, pathophysiology, treatments, and outcomes.

Artificial Intelligence and Myocardial Contrast Enhancement Pattern

PURPOSE OF REVIEW

Machine learning (ML) and deep learning (DL) are two important categories of AI algorithms. Nowadays, AI technology has been gradually applied to cardiac magnetic resonance imaging (CMRI), covering the fields of myocardial contrast enhancement (MCE) pattern and automatic ventricular segmentation. This paper mainly discusses the relationship between machine learning and deep learning based on AI and pattern of MCE in CMRI.

RECENT FINDINGS

It found that some histogram and GLCM parameters in ML algorithm had significant statistical differences in diagnosis of cardiomyopathy and differentiation of fibrosis and normal myocardial tissue. In the DL algorithm, there was no significant difference between CNN and observers in measuring myocardial fibrosis. The rapid development of texture parameter analysis methods would promote the medical imaging based on AI into a new era. Histogram and GLCM parameters are the research hotspot of unsupervised learning of MCE images. CNN has a great advantage in automatically identifying and quantifying myocardial fibrosis reflected by LGE images.

The best way to assess oedema using T1, T2 mapping or three-dimensional T2-weighted fast-spin-echo triple inversion recovery sequences via cardiovascular MRI in outpatients with suspected myocarditis

AIM

To evaluated T1-, T2 mapping, and a three-dimensional (3D) T2-weighted fast-spin-echo triple inversion recovery sequences (3D STIR) for diagnosing myocardial oedema in patients with suspected early myocarditis and at follow-up.

MATERIALS AND METHODS

Sixteen patients with suspected myocarditis and 15 controls matched for gender and age were examined prospectively. To evaluate oedema, an electrocardiogram-triggered T1 and T2 mapping with a gradient spin echo technique and 3D STIR sequences were used to cover the entire left ventricle. The signal intensity ratio (heart muscle in relation to skeletal muscle) was calculated (3D STIR ratio). All patients underwent repeat examinations at follow-up.

RESULTS

The mean 3D-STIR ratio was 2.14±0.45 at the patients' initial examination as compared to the control patients' 1.54±0.18 in (p=0.0001) and 1.75±0.16 in patients at follow-up (p=0.002 versus first visit). The 3D STIR ratio of the septum, anterior, lateral, and inferior wall also differed significantly between patients and controls. No significant difference was observed in T1 and T2 mapping between patients and controls at baseline and patients at follow-up.

CONCLUSIONS

A significantly higher global signal intensity ratio with 3D-STIR was identified in patients with suspected myocarditis compared to controls, and a significant change during follow-up. No significant difference was detected in T1-, T2 mapping between patients and controls, or between the initial examination and follow-up of patients. The global 3D-STIR ratio may therefore be useful for the diagnosis of myocarditis and should be explored further.

Cardiovascular Magnetic Resonance in Nonischemic Myocardial Inflammation: Expert Recommendations

This JACC Scientific Expert Panel provides consensus recommendations for an update of the cardiovascular magnetic resonance (CMR) diagnostic criteria for myocardial inflammation in patients with suspected acute or active myocardial inflammation (Lake Louise Criteria) that include options to use parametric mapping techniques. While each parameter may indicate myocardial inflammation, the authors propose that CMR provides strong evidence for myocardial inflammation, with increasing specificity, if the CMR scan demonstrates the combination of myocardial edema with other CMR markers of inflammatory myocardial injury. This is based on at least one T2-based criterion (global or regional increase of myocardial T2 relaxation time or an increased signal intensity in T2-weighted CMR images), with at least one T1-based criterion (increased myocardial T1, extracellular volume, or late gadolinium enhancement). While having both a positive T2-based marker and a T1-based marker will increase specificity for diagnosing acute myocardial inflammation, having only one (i.e., T2-based OR T1-based) marker may still support a diagnosis of acute myocardial inflammation in an appropriate clinical scenario, albeit with less specificity. The update is expected to improve the diagnostic accuracy of CMR further in detecting myocardial inflammation.

Early diastolic septal movement in patients with myocarditis

AIM

To evaluate early diastolic septal relaxation as a parameter in the diagnostic workup via cardiovascular magnetic resonance imaging (CMRI) in patients with myocarditis.

MATERIALS AND METHODS

Early diastolic septal movement was evaluated (EDS) prospectively via frame-by-frame analysis in 255 consecutive patients with presenting signs of myocarditis and in 64 controls matched 4:1 for gender and age. ECG-triggered, T2-weighted, fast spin echo triple inversion recovery sequences and late gadolinium enhancement were obtained, as well as left ventricular (LV) function and dimensions in patients and controls.

RESULTS

EDS was detected in 66.7% of the patients and 18.7% of the controls (p<0.001). Sensitivity was 69.4% and specificity 79.7%. Patients with EDS had a significant lower LV ejection fraction (LV-EF) of 61.1±0.6% and significant higher end-diastolic volume (EDV) of 158.5±2.7 ml than in patients without EDS (LV-EF 65.3±0.9%, p=0.0001; EDV 148.4±3.9 ml, p=0.04). A significant negative correlation was observed between LV-EF and EDS in patients, and a lower LV-EF correlated with a more frequent occurrence of EDS (r=-0.24, p=0.0001). Scar tissue was also more frequent in patients than controls (63.1% and 7.8%, p=0.007).

CONCLUSIONS

EDS is a parameter obtained non-invasively by CMRI and is present in a high percentage of patients with myocarditis. Cardiac functional parameters are significantly altered in patients with EDS. EDS is a feasible parameter that can play an important role in the diagnosis of myocarditis.

Patients with exercise-associated ventricular ectopy present evidence of myocarditis

BACKGROUND

The origin and clinical relevance of exercise-induced premature ventricular beats (PVBs) in patients without coronary heart disease or cardiomyopathies is unknown. Cardiovascular magnetic resonance enables us to non-invasively assess myocardial scarring and oedema. The purpose of our study was to discover any evidence of myocardial anomalies in patients with exercise-induced ventricular premature beats.

METHODS

We examined 162 consecutive patients presenting palpitations and documented exercise-induced premature ventricular beats (PVBs) but no history or evidence of structural heart disease. Results were compared with 70 controls matched for gender and age. ECG-triggered, T2-weighted, fast spin echo triple inversion recovery sequences and late gadolinium enhancement were obtained as well as LV function and dimensions.

RESULTS

Structural anomalies in the myocardium and/or pericardium were present in 85 % of patients with exercise-induced PVBs. We observed a significant difference between patients with PVBs and controls in late gadolinium enhancement, that is 68 % presented subepicardial or midmyocardial lesions upon enhancement, whereas only 9 % of the controls did so (p < 0.0001). More patients presented pericardial enhancement (35 %) or pericardial thickening (27 %) compared to controls (21 % and 13 %, p < 0.0001). Myocardial oedema was present in 37 % of the patients and in only one control, p < 0.0001. Left ventricular ejection fraction did not differ between patients and controls (63.1 ± 7.9 vs. 64.7 ± 7.0, p = 0.13).

CONCLUSIONS

The majority of patients with exercise-associated premature ventricular beats present evidence of myocardial disease consistent with acute or previous myocarditis or myopericarditis.

Cardiovascular magnetic resonance techniques and findings in children with myocarditis: a multicenter retrospective study

BACKGROUND

Cardiovascular magnetic resonance (CMR) is increasingly used to diagnose myocarditis in adults but its use in children is not well-established. We sought to describe the presentation, CMR protocol and findings, and outcomes in a multicenter cohort of children with myocarditis.

METHODS

Thirteen hospitals retrospectively identified patients meeting the following inclusion criteria: 1) diagnosis of myocarditis by the managing physicians, 2) age <21 years, 3) CMR examination within 30 days of presentation, and 4) no congenital heart disease. Clinical data and test results, including CMR findings, were abstracted from the medical record.

RESULTS

For the 143 patients meeting inclusion criteria, the median age was 16.0 years (range, 0.1-20.3) and 139 (97 %) were hospitalized at the time of CMR. The median time from presentation to CMR was 2 days (0-28). The median left ventricular ejection fraction at CMR was 56 % (10-74), with 29 (20 %) below 45 %. The median right ventricular ejection fraction was 54 % (15-72), with 11 (8 %) below 40 %. There was significant variability among centers in the types of tissue characterization techniques employed (p < 0.001). Overall, late gadolinium enhancement (LGE) was used in 100 % of studies, followed by T2-weighted imaging (T2W) in 69 %, first-pass contrast perfusion (FPP) in 48 %, and early gadolinium enhancement (EGE) in 28 %. Abnormalities were most common with LGE (81 %), followed by T2W (74 %), EGE (55 %), and FPP (8 %). The CMR study was interpreted as positive for myocarditis in 117 patients (82 %), negative in 18 (13 %), and equivocal in 7 (5 %), yielding a sensitivity of 82 %. At a median follow-up of 7.1 months (0-87), all patients were alive and 5 had undergone cardiac transplantation. CMR parameters at presentation associated with persistent left ventricular dysfunction were larger left ventricular end-diastolic volume and lower left and right ventricular ejection fraction but not abnormal LGE.

CONCLUSIONS

Despite significant practice variation in imaging protocol among centers, CMR had a high sensitivity for the diagnosis of myocarditis in pediatric patients. Abnormalities were most often seen with LGE followed by T2W, EGE, and FPP. These findings should be useful in designing future prospective studies.

How to approach the great mimic? Improving techniques for the diagnosis of myocarditis

Myocarditis is characterized by inflammation of the myocardium, assessed by histological, immunological and immunohistochemical criteria, due to exogenous or endogenous causes. Abnormal QRS, increased troponin T and left ventricular regional or global dysfunction may be detected. Strain Doppler echocardiography can detect longitudinal segmental dysfunction of the myocardium, due to edema, which is in agreement with cardiac magnetic resonance imaging. Nuclear imaging shows a good sensitivity, but carries serious limitations. Somatostatin receptor positron emission tomography/computed tomography seems promising. Cardiac magnetic resonance imaging, using T2-weighted, early T1-weighted, delayed enhanced images and recently T2 and T1 mapping, has the best diagnostic capability. Endomyocardial biopsy has further contributed to the etiologic diagnosis of myocarditis. To conclude, cardiac magnetic resonance and endomyocardial biopsy have both significantly increased our diagnostic performance. However, further assessment by multicenter studies is needed to establish a clinically useful algorithm.

New-Onset Myocarditis in an Immunocompetent Adult with Acute Metapneumovirus Infection

Introduction. A number of viruses have been implicated in viral myocarditis; however, there has been no previous report of human metapneumovirus (hMPV) causing this condition. Discovered in 2001, hMPV is typically associated with upper respiratory illness, mainly affecting children. Case Presentation. We report the case of a 25-year-old man with acute systolic heart failure from viral myocarditis secondary to the hMPV. The patient was initially admitted to the general medical ward but developed increasing oxygen requirements resulting in transfer to the cardiac intensive care unit. Cardiac magnetic resonance imaging was used to help confirm the diagnosis. He was treated with intravenous diuretics, and afterload and preload agents, and he was subsequently discharged home after seven days of hospitalization. Discussion. hMPV is typically a respiratory pathogen; however, it was associated with in myocarditis in our patient. Due to the recent ability to detect this virus, we may see more cases of this, particularly during peak months of infection. Conclusion. This is the first case description of myocarditis associated with hMPV infection.

Evaluation of the diagnostic work-up in children with myocarditis and idiopathic dilated cardiomyopathy

The underlying etiology of dilated cardiomyopathy (DCM) in children varies, 14-22% is secondary to myocarditis, and the majority remains idiopathic. Etiology has prognostic value; however, 'a clinical diagnosis of myocarditis' has been frequently used because the gold standard [endomyocardial biopsy (EMB)] is often not performed. Therefore, a consistent diagnostic approach and interpretation is needed. In this multicenter study, we evaluated the diagnostic approach and interpretation of the viral results in children with myocarditis and idiopathic DCM. We included 150 children with DCM, of whom 103 were assigned the diagnosis myocarditis (n = 21) or idiopathic DCM (n = 82) by the attending physician. Viral tests were performed in 97/103 patients, in only 34% (n = 35) some of the tests were positive. Of those patients, we evaluated the probability of the assigned diagnosis using the viral test results. We classified viral test results as reflecting definite or probable myocarditis in 14 children and possible or unlikely myocarditis in 21 children. Based on this classification, 23% of patients were misclassified. We found that in children with DCM, the diagnostic approach varied and the interpretation was mainly based on viral results. Since a 'clinical diagnosis of myocarditis' has been frequently used in daily practice because of the lack of EMB results, a uniform protocol is needed. We propose to use viral test results in several steps (blood PCR, serology, PCR and/or cultures of the gastro-intestinal and respiratory tract, and EMB results) to estimate the probability of myocarditis.

2014 korean guidelines for appropriate utilization of cardiovascular magnetic resonance imaging: a joint report of the korean society of cardiology and the korean society of radiology

Cardiac magnetic resonance (CMR) imaging is now widely used in several fields of cardiovascular disease assessment due to recent technical developments. CMR can give physicians information that cannot be found with other imaging modalities. However, there is no guideline which is suitable for Korean people for the use of CMR. Therefore, we have prepared a Korean guideline for the appropriate utilization of CMR to guide Korean physicians, imaging specialists, medical associates and patients to improve the overall medical system performances. By addressing CMR usage and creating these guidelines we hope to contribute towards the promotion of public health. This guideline is a joint report of the Korean Society of Cardiology and the Korean Society of Radiology.

2014 Korean guidelines for appropriate utilization of cardiovascular magnetic resonance imaging: a joint report of the Korean Society of Cardiology and the Korean Society of Radiology

Cardiac magnetic resonance (CMR) imaging is now widely used in several fields of cardiovascular disease assessment due to recent technical developments. CMR can give physicians information that cannot be found with other imaging modalities. However, there is no guideline which is suitable for Korean people for the use of CMR. Therefore, we have prepared a Korean guideline for the appropriate utilization of CMR to guide Korean physicians, imaging specialists, medical associates and patients to improve the overall medical system performances. By addressing CMR usage and creating these guidelines we hope to contribute towards the promotion of public health. This guideline is a joint report of the Korean Society of Cardiology and the Korean Society of Radiology.

Combined electrocardiography, coronary angiography and magnetic resonance imaging for the diagnosis of viral myocarditis: A case report

Endomyocardial biopsy is the gold standard for diagnosing viral myocarditis. However, this method is rarely used as it is more invasive, less sensitive and has a higher incidence of complications than other methods. With recent developments in myocarditis research, cardiovascular nuclear magnetic resonance imaging has been demonstrated to have a marked advantage over endomyocardial biopsy, specifically regarding the differential diagnosis of acute coronary syndrome, as it is noninvasive, repeatable, highly sensitive and highly specific for diagnosing myocarditis. Myocardial edema is characteristic of myocardial inflammation, myocardial necrosis and myocardial fibrosis. T2-weighted nuclear magnetic resonance imaging sensitively detects myocardial tissue edema and additional imaging parameters contribute to the diagnosis of myocarditis. Therefore, combining these methods with the current sophisticated electrocardiogram and coronary angiography examination methods may facilitate the rapid and accurate assessment of viral myocarditis. A 44-year-old male patient with symptoms of dyspnea and shortness of breath accompanied by dizziness, through electrocardiography, coronary angiography and magnetic resonance imaging, was diagnosed viral myocarditis.