Cardiovascular Magnetic Resonance in Nonischemic Myocardial Inflammation: Expert Recommendations

Recognition and Initial Management of Fulminant Myocarditis: A Scientific Statement From the American Heart Association

Fulminant myocarditis (FM) is an uncommon syndrome characterized by sudden and severe diffuse cardiac inflammation often leading to death resulting from cardiogenic shock, ventricular arrhythmias, or multiorgan system failure. Historically, FM was almost exclusively diagnosed at autopsy. By definition, all patients with FM will need some form of inotropic or mechanical circulatory support to maintain end-organ perfusion until transplantation or recovery. Specific subtypes of FM may respond to immunomodulatory therapy in addition to guideline-directed medical care. Despite the increasing availability of circulatory support, orthotopic heart transplantation, and disease-specific treatments, patients with FM experience significant morbidity and mortality as a result of a delay in diagnosis and initiation of circulatory support and lack of appropriately trained specialists to manage the condition. This scientific statement outlines the resources necessary to manage the spectrum of FM, including extracorporeal life support, percutaneous and durable ventricular assist devices, transplantation capabilities, and specialists in advanced heart failure, cardiothoracic surgery, cardiac pathology, immunology, and infectious disease. Education of frontline providers who are most likely to encounter FM first is essential to increase timely access to appropriately resourced facilities, to prevent multiorgan system failure, and to tailor disease-specific therapy as early as possible in the disease process.

Immune Checkpoint Inhibitors (ICIs)-Related Cardiotoxicity

The growing success of immune checkpoint inhibitors (ICIs) has led to effectively treating several types of cancers. Even though their use has been associated with the development of cardiac adverse effects, which may decrease the overall survival in cancer patients. These cardiac toxicities are thought to be the result of targeting specific checkpoint proteins on normal myocardial cells leading to over stimulation of the immune system as well as secondary downstream off-target effects on normal tissue.Although cardiotoxicities related to immunotherapy are reportedly rare, they can be severe and associated with life-threatening conditions such as fulminant myocarditis, hemodynamic instability, and cardiac arrest.We will review the most commonly reported cardiovascular toxicities associated with ICIs and their management.

CMR Parametric Mapping as a Tool for Myocardial Tissue Characterization

Cardiovascular magnetic resonance (CMR) is the current gold standard for imaging cardiac anatomy, function, and advanced myocardial tissue characterization. After cine, late gadolinium enhancement (LGE), and perfusion imaging, parametric mapping is widely regarded as the 4th era of myocardial CMR development. In contrast to conventional CMR tissue characterization techniques, which rely on relative variations in image intensities to highlight abnormal tissues, parametric mapping provides direct visualization of tissue MR properties such as T1, T2 and T2* in absolute denominations (e.g. in milliseconds). Presentation as pixel-wise parametric maps adds spatial information for a more complete assessment of the myocardium. Advantages of parametric mapping include direct, quantitative comparisons inter- and within-individuals, as well as detection of diffuse disease not evident on conventional CMR imaging, without the need for contrast agents. CMR parametric mapping methods have matured over the past decade into clinical tools, demonstrating not only clinical utility but added value in a wide range of cardiac diseases. They are particularly useful for the evaluation of acute myocardial injury, suspected infiltration and heart failure of unclear etiology. This review discusses the background of parametric mapping, particularly T1-, T2- and ECV-mapping, general magnetic resonance physics principles, clinical applications (including imaging protocols, image analysis and reporting guidelines), current challenges and future directions. CMR parametric mapping is increasingly available on routine clinical scanners, and promises to deliver advanced myocardial tissue characterization beyond conventional CMR techniques, ultimately helping clinicians to benefit patients in their clinical management.

Cardiovascular Magnetic Resonance Identifies High-Risk Systemic Sclerosis Patients with Normal Echocardiograms and Provides Incremental Prognostic Value

BACKGROUND

Acute cardiac events are a significant contributor to mortality in systemic sclerosis (SSc). However, echocardiographic evaluation may be deceptively normal during an acute presentation. We hypothesized that in diffuse SSc patients presenting with acute cardiac events and a normal echocardiogram, cardiovascular magnetic resonance (CMR) would have incremental diagnostic/prognostic value.

METHODS

50 consecutive diffuse SSc patients with normal echocardiograms were evaluated using a 1.5T system. A total of 27 (63%) had experienced an acute cardiac event three to tendays before CMR evaluation (rhythm disturbances, angina pectoris, shortness of breath). Left/right ventricular (LV/RV) volumes and ejection fractions (EF), as well as LV mass, the T2-signal ratio, early/late gadolinium enhancement (EGE/LGE), native/post-contrast T1-mapping, T2-mapping and extracellular volume fraction (ECV) were compared between the event and no-event groups.

RESULTS

No differences were identified in LV/RV volumes/EF/mass. In logistic regression analyses, independent predictors of belonging to the event group were EGE (odds ratio (95% CI): 1.55 (1.06-2.26), p = 0.024), LGE (1.81 (1.23-2.67), p = 0.003), T2 mapping (1.20 (1.06-1.36), p = 0.004) and native/post-contrast T1 mapping (1.17 (1.04-1.32), p = 0.007 and 0.86 (0.75-0.98), p = 0.025). At a median follow-up of ~1.2 years, 42% vs. 11% of the event/no-event group respectively reached a combined endpoint of event occurrence/recurrence or cardiovascular mortality. Of the independent predictors resulting from logistic regression analyses, only LGE (hazard ratio (95% CI): 1.20 (1.11-1.30), p < 0.001), T2-mapping (1.07 (1.01-1.14), p = 0.025) and native T1-mapping (1.08 (1.01-1.15), p = 0.017) independently predicted the combined endpoint.

CONCLUSIONS

A normal echocardiogram does not preclude myocardial lesions in diffuse SSc patients, which can be detected by CMR especially in symptomatic patients.

Strain analysis reveals subtle systolic dysfunction in confirmed and suspected myocarditis with normal LVEF. A cardiac magnetic resonance study

AIMS

Lake Louise Criteria (LLC) are time-dependent and some acute myocarditis (AM) with preserved left ventricular ejection fraction (LVEF) could be missed, due to the limited accessibility of Cardiac Magnetic Resonance (CMR). We aimed to assess the potential value of cardiac strain measured by feature tracking (FT) imaging in this population.

METHODS AND RESULTS

Eighty-three patients with clinically suspected AM and normal LVEF were divided into 39 "confirmed AM" (positive LLC) and 44 "suspected AM" (negative LLC). An age and gender-matched sample of 42 normal subjects underwent CMR. In all groups, FT-derived biventricular strains and STE- global longitudinal strain (GLS) were assessed, being regularly measurable. Strain values < 5th percentile of the control group were considered abnormal. "Suspected" and "confirmed" AM were similar, except for medium time of CMR evaluation (5.2 vs 1 months from presentation, respectively; p = 0.004). Compared to healthy controls, both "suspected" and "confirmed" AM showed significantly impaired strain values. LV-global circumferential strain (GCS), right ventricular GCS and LV-GLS were abnormal in 15.4% and 15.9%, 20.5% and 15.9%, 7.7% and 9.1% in "confirmed" and "suspected" AM, respectively. STE analysis confirmed the results on LV-GLS, however a weak correlation emerged between STE and CMR-FT LV-GLS (p = 0.08).

CONCLUSIONS

Compared to STE, CMR-FT analysis provided a more comprehensive and complementary biventricular strain evaluation that resulted similar in "confirmed" and "suspected" AM with normal LVEF. Conversely, mostly biventricular GCS was significantly reduced in up to 20% of patients, compared to healthy controls.

Arrhythmogenic Inflammatory Cardiomyopathy in Autoimmune Rheumatic Diseases: A Challenge for Cardio-Rheumatology

Ventricular arrhythmia (VA) in autoimmune rheumatic diseases (ARD) is an expression of autoimmune inflammatory cardiomyopathy (AIC), caused by structural, electrical, or inflammatory heart disease, and has a serious impact on a patient's outcome. Myocardial scar of ischemic or nonischemic origin through a re-entry mechanism facilitates the development of VA. Additionally, autoimmune myocardial inflammation, either isolated or as a part of the generalized inflammatory process, also facilitates the development of VA through arrhythmogenic autoantibodies and inflammatory channelopathies. The clinical presentation of AIC varies from oligo-asymptomatic presentation to severe VA and sudden cardiac death (SCD). Both positron emission tomography (PET) and cardiovascular magnetic resonance (CMR) can diagnose AIC early and be useful tools for the assessment of therapies during follow-ups. The AIC treatment should be focused on the following: (1) early initiation of cardiac medication, including ACE-inhibitors, b-blockers, and aldosterone antagonists; (2) early initiation of antirheumatic medication, depending on the underlying disease; and (3) potentially implantable cardioverter-defibrillator (ICD) and/or ablation therapy in patients who are at high risk for SCD.

Advances in MRI Applications to Diagnose and Manage Cardiomyopathies

PURPOSE OF REVIEW

The prevalence of heart failure continues to rise, and imaging characterization of the cardiomyopathic process is important for identifying myocardial disease, initiating appropriate treatment, and improving outcomes. We aimed to summarize recent advances in cardiac magnetic resonance imaging (CMR) applications for the diagnosis, characterization, and implications on management of various cardiomyopathies.

RECENT FINDINGS

Parametric mapping by CMR has emerged as an important advancement in quantification of myocardial fibrosis, increased extracellular space, and myocardial edema. In addition, improved assessment of myocardial function with myocardial strain assessment may provide early identification of patients at risk and determining responsiveness to therapeutic interventions. Novel MRI techniques and the advent of artificial intelligence may help to uncover important mechanistic insights into the cardiomyopathic process. Innovative CMR techniques continue to evolve, and it will be of interest to determine how these advances can be incorporated into clinical practice to improve diagnosis, treatment, and management of patients with cardiomyopathies.

Myocardial phenotypes and dysfunction in HFpEF and HFrEF assessed by echocardiography and cardiac magnetic resonance

Heart failure (HF) with either reduced or preserved ejection fraction is an increasingly prevalent condition. Cardiac imaging plays a central role in trying to identify the underlying cause of the underlying systolic and diastolic dysfunction, as the imaging findings have implications for patient's management and individualised treatment. The imaging modalities used more frequently in patients with heart failure in clinical routine are echocardiography and cardiac magnetic resonance. Both techniques keep some strengths and weakness due to their spatial and temporal resolution. Notably, several features in the diagnostic algorithm of heart failure with preserved systolic function (HFpEF) may be improved by an integrated approach. This review focuses on the role of each modality in characterising cardiac anatomy, systolic and diastolic function as well as myocardial tissue characterisation in the most common phenotypes of dilated and hypertrophied hearts.

Non-contrast enhanced diagnosis of acute myocarditis based on the 17-segment heart model using 2D-feature tracking magnetic resonance imaging

PURPOSE

The aim of this study was to investigate the diagnostic value of myocardial deformation analysis based on the 17-segment heart model using non-contrast enhanced (CE) 2D tissue feature tracking (2D-FT) technique.

MATERIAL AND METHODS

Seventy patients with suspected myocarditis underwent a cardiovascular magnetic resonance (CMR) examination at 1.5 Tesla. A contrast-agent-free part of this CMR protocol was additionally performed in forty healthy volunteers (HV). Besides standard CMR data sets, 2D-FT derived segmental and global longitudinal, radial, and circumferential deformation parameters were analyzed. The 2D-FT results were compared to the combined findings from CMR imaging and endomyocardial biopsy (EMB).

RESULTS

Patients were assigned to three groups depending on their ejection fraction (EF) (<40%, 40-55%, ≥55%). Compared to HV, impaired EF (<55%) was significantly correlated to reduced segmental and global strain and strain rate values. The circumferential deformation analysis was more sensitive to myocardial changes than longitudinal and radial analysis. The segmental strain/strain rate had an accuracy of 84.3%/70.0% for the diagnosis of an acute myocarditis, stated by EMB and CMR in 42 of 70 patients. In patients with preserved EF, acute myocarditis could be ruled out using only segmental strain analysis with a negative predictive value of 87.5%.

CONCLUSION

In patients with suspected myocarditis, the deformation analysis based on the 17-segment heart model provides valuable information about functional myocardial inhomogeneity. This quantitative approach could be used in addition to the clinical standard CMR protocol and represents a promising tool in the framework of a prospective automatized multiparametric CMR imaging analysis.

Myocardial T1 and ECV Measurement: Underlying Concepts and Technical Considerations

Myocardial native T1 and extracellular volume fraction (ECV) mapping have emerged as cardiac magnetic resonance biomarkers providing unique insight into cardiac pathophysiology. Single breath-hold acquisition techniques, available on clinical scanners across multiple vendor platforms, have made clinical T1 and ECV mapping a reality. Although the relationship between changes in native T1 and alterations in cardiac microstructure is complex, an understanding of how edema, blood volume, myocyte and interstitial expansion, lipids, and paramagnetic substances affect T1 and ECV can provide insight into how and why these parameters change in various cardiac pathologies. The goals of this state-of-the-art review will be to review factors influencing native T1 and ECV, to describe how native T1 and ECV are measured, to discuss potential challenges and pitfalls in clinical practice, and to describe new T1 mapping techniques on the horizon.

Cardiac magnetic resonance imaging with late gadolinium enhancement in acute myocarditis: Towards differentiation between immune-mediated and viral-related aetiologies

BACKGROUND

Diagnosing immune-mediated myocarditis is challenging because of non-specific clinical signs and symptoms. Cardiac magnetic resonance imaging (CMR) provides subepicardial late gadolinium enhancement (LGE) in the setting of acute myocarditis, but the diagnostic value of LGE pattern for differentiating between immune-mediated and viral-related aetiologies remains unknown.

AIMS

To determine the value of LGE pattern for differentiating between immune-mediated and viral-related aetiologies in patients with acute myocarditis.

METHODS

One hundred and five patients with acute myocarditis who underwent CMR, including LGE variables, were included retrospectively. Viral-related aetiology was retained with a negative autoimmune and autoinflammatory assessment at diagnosis and 6-month follow-up.

RESULTS

Aetiology was immune-mediated in 31 patients and viral-related in 74 patients. Patients with immune-mediated myocarditis were older (55±16 vs. 31±12years; P<0.001) and more likely to be female (52% vs. 14%; P<0.001) than those with viral-related myocarditis. There was no difference in left ventricular ejection fraction between the immune-mediated and viral-related myocarditis groups (53±15% vs. 57±8%; P=0.61). Regarding LGE, patients with viral-related myocarditis were more likely to have basal anteroseptal, mid anteroseptal, mid anterior and basal anterolateral location. Patients with immune-mediated myocarditis were more likely to have apical septal, apical inferior, apical lateral, mid anterolateral and basal inferior location. Segments with difference in prevalence of LGE between aetiologies were summed to build a score where positive significant association with immune-mediated myocarditis was quoted 1 and positive significant association with viral-related myocarditis was quoted -1. A score≥0 differentiated immune-mediated from viral-related myocarditis with 94% sensitivity and 77% specificity (area under the receiver operating characteristic curve 0.88; P<0.001).

CONCLUSION

CMR provides arguments for differentiating immune-mediated from viral-related acute myocarditis by showing preferential LGE localization in apical septal, apical inferior, apical lateral and basal inferior segments.

Role of multimodality imaging in the diagnosis and management of cardiomyopathies

Multimodality imaging plays an important role in the initial evaluation, diagnosis and management of patients suspected of having a cardiomyopathy. Beyond functional and anatomical information, multimodality imaging provides important variables that facilitate risk stratification and prognosis evaluation. Whatever the underlying suspected cardiomyopathy, echocardiography is the most common initial imaging test used to establish the presence of cardiomyopathy, by depicting structural and functional abnormalities. However, echocardiographic findings are non-specific, and therefore have a limited role in identifying the underlying aetiology. Cardiac magnetic resonance imaging allows characterization of myocardial tissue, which can be of great help in identifying the aetiology of the cardiomyopathy. When a specific aetiology is suspected, particularly inflammation, ¹⁸F-fluorodeoxyglucose positron emission tomography is recommended. The clinician should be capable of selecting the appropriate imaging techniques for each clinical scenario. Each technique has strengths and weaknesses, which should be known. In order to improve diagnostic performance, and as proposed by the European Association for Cardiovascular Imaging, cardiovascular imaging groups must be composed of experts from all modalities. The future of multimodality imaging in the diagnosis and management of cardiomyopathies will also involve evolution of its use in care, teaching and research. Training goals for future cardiac imaging experts must be defined; academic and industry partnerships should enable the connection to be made between imaging data and clinical data on the one hand and outcomes on the other hand, using big-data analysis and artificial intelligence.

Cardiac magnetic resonance imaging: the future is bright

Over the last 15 years, cardiovascular magnetic resonance (CMR) imaging has progressively evolved to become an indispensable tool in cardiology. It is a non-invasive technique that enables objective and functional assessment of myocardial tissue. Recent innovations in magnetic resonance imaging scanner technology and parallel imaging techniques have facilitated the generation of T1 and T2 parametric mapping to explore tissue characteristics. The emergence of strain imaging has enabled cardiologists to evaluate cardiac function beyond conventional metrics. Significant progress in computer processing capabilities and cloud infrastructure has supported the growth of artificial intelligence in CMR imaging. In this review article, we describe recent advances in T1/T2 mapping, myocardial strain, and artificial intelligence in CMR imaging.

Imaging of myocarditis and inflammatory cardiomyopathies

Myocarditis encompasses a wide range of myocardial inflammatory diseases, including acute myocarditis, chronic myocarditis and inflammatory cardiomyopathies, and myocardial inflammation associated with other cardiomyopathies. Because of this heterogeneity in clinical presentation, and the infrequent use of endomyocardial biopsy, cardiac imaging has gradually acquired a key role in the non-invasive detection of myocardial inflammation, the assessment of aetiology and the management of specific therapies. This article summarizes the issue of myocarditis and myocardial inflammation in clinical practice, and reviews the role of different non-invasive imaging techniques in the exploration of myocardial inflammation.

MRI of Cardiotoxicity

Cardiovascular magnetic resonance (CMR) imaging is useful to identify systolic dysfunction, particularly when echocardiographic imaging is not acceptable because of poor acoustic windows or when left ventricular ejection fraction (LVEF) is inconclusive by other modalities and an accurate LVEF measurement is needed. Of particular advantage in cardio-oncology is CMR's capability to perform tissue characterization to noninvasively identify changes in pathologic conditions related to cancer therapy or to discriminate causes of disease that may confound presentation in cardio-oncology patients. For these reasons, there is an increasing use of CMR in the screening and surveillance of cardio-oncology patients.

Multiparametric cardiovascular magnetic resonance imaging in acute myocarditis: a comparison of different measurement approaches

BACKGROUND

Myocardial T1 and T2 mapping are reliable diagnostic markers for the detection and follow up of acute myocarditis. The aim of this study was to compare the diagnostic performance of current mapping measurement approaches to differentiate between myocarditis patients and healthy individuals.

METHODS

Fifty patients with clinically defined acute myocarditis and 30 healthy controls underwent cardiovascular magnetic resonance (CMR). Myocardial T1 relaxation times, T2 relaxation times, left ventricular (LV) function, T2 ratio, early gadolinium enhancement ratio, and presence of late gadolinium enhancement (LGE) were analysed. Native T1 and T2 relaxation times, as well as extracellular volume fraction (ECV) were measured for the entire LV myocardium (global), within the midventricular short axis slice (mSAX), within the midventricular septal wall (ConSept), and within the remote myocardium (remote). Receiver operating characteristics analysis was performed to compare diagnostic performance.

RESULTS

All measurement approaches revealed significantly higher native T1 and T2 relaxation times as well as ECV values in patients compared to healthy controls (p < 0.05 for all parameters). The global measurement approach showed highest diagnostic performance regarding all mapping parameters (AUCs, native T1: 0.903, T2: 0.847, ECV: 0.731). Direct comparison of the different measurement approaches revealed significant differences in diagnostic performance between the global and the remote approach regarding T1 relaxation times and ECV (p = 0.001 and p = 0.002 respectively). Further, the global measurement approach revealed significantly higher T1 relaxation times compared to the ConSept approach (AUCs: 0.903 vs. 0.783; p = 0.003) and nearly significant differences compared to the mSAX approach (AUC: 0.850; p = 0.051). T2 relaxation times showed no significant differences between all measurement approaches (p > 0.050 for all parameters).

CONCLUSIONS

Native T1 and T2 mapping allow for accurate detection of acute myocarditis irrespective of the measurement approach used. Even measurements performed exclusively within remote myocardium allow for reliable detection of acute myocarditis, demonstrating diffuse involvement of disease despite a mostly regional or patchy distribution pattern of visible pathologies. The global measurement approach provides the overall best diagnostic performance in acute myocarditis for both T1 and T2 mapping.

Assessment and Treatment of Patients With Type 2 Myocardial Infarction and Acute Nonischemic Myocardial Injury

Although coronary thrombus overlying a disrupted atherosclerotic plaque has long been considered the hallmark and the primary therapeutic target for acute myocardial infarction (MI), multiple other mechanisms are now known to cause or contribute to MI. It is further recognized that an MI is just one of many types of acute myocardial injury. The Fourth Universal Definition of Myocardial Infarction provides a taxonomy for acute myocardial injury, including 5 subtypes of MI and nonischemic myocardial injury. The diagnosis of MI is reserved for patients with myocardial ischemia as the cause of myocardial injury, whether attributable to acute atherothrombosis (type 1 MI) or supply/demand mismatch without acute atherothrombosis (type 2 MI). Myocardial injury in the absence of ischemia is categorized as acute or chronic nonischemic myocardial injury. However, optimal evaluation and treatment strategies for these etiologically distinct diagnoses have yet to be defined. Herein, we review the epidemiology, risk factor associations, and diagnostic tools that may assist in differentiating between nonischemic myocardial injury, type 1 MI, and type 2 MI. We identify limitations, review new research, and propose a framework for the diagnostic and therapeutic approach for patients who have suspected MI or other causes of myocardial injury.

Characterization of acute TLR-7 agonist-induced hemorrhagic myocarditis in mice by multiparametric quantitative cardiac magnetic resonance imaging

Hemorrhagic myocarditis is a potentially fatal complication of excessive levels of systemic inflammation. It has been reported in viral infection, but is also possible in systemic autoimmunity. Epicutaneous treatment of mice with the Toll-like receptor 7 (TLR-7) agonist Resiquimod induces auto-antibodies and systemic tissue damage, including in the heart, and is used as an inducible mouse model of systemic lupus erythematosus (SLE). Here, we show that overactivation of the TLR-7 pathway of viral recognition by Resiquimod treatment of CFN mice induces severe thrombocytopenia and internal bleeding, which manifests most prominently as hemorrhagic myocarditis. We optimized a cardiac magnetic resonance (CMR) tissue mapping approach for the in vivo detection of diffuse infiltration, fibrosis and hemorrhages using a combination of T1, T2 and T2* relaxation times, and compared results with ex vivo histopathology of cardiac sections corresponding to CMR tissue maps. This allowed detailed correlation between in vivo CMR parameters and ex vivo histopathology, and confirmed the need to include T2* measurements to detect tissue iron for accurate interpretation of pathology associated with CMR parameter changes. In summary, we provide detailed histological and in vivo imaging-based characterization of acute hemorrhagic myocarditis as an acute cardiac complication in the mouse model of Resiquimod-induced SLE, and a refined CMR protocol to allow non-invasive longitudinal in vivo studies of heart involvement in acute inflammation. We propose that adding T2* mapping to CMR protocols for myocarditis diagnosis improves diagnostic sensitivity and interpretation of disease mechanisms.This article has an associated First Person interview with the first author of the paper.

Diagnostic and prognostic value of cardiac magnetic resonance in acute myocarditis: a systematic review and meta-analysis

While diagnostic criteria were elaborated for acute myocarditis using cardiac magnetic resonance (CMR) in 2009, studies have since examined the yield of traditional and novel CMR parameters to achieve greater accuracy and to predict clinical outcomes. The purpose of this systematic review and meta-analysis was to determine the diagnostic and prognostic value of CMR parameters for acute myocarditis. MEDLINE and EMBASE were systematically searched for original studies that reported CMR parameters in adult patients suspected of acute myocarditis. Each CMR parameter's binary prevalence, mean value and standard deviation were extracted. Parameters were meta-analyzed using a random-effects model to generate standardized mean differences. After screening 1492 abstracts, 53 studies were included encompassing 2823 myocarditis patients and 803 controls. Pooled standardized mean differences between myocarditis patients and controls were: T2 mapping time 2.26 (95% CI 1.50-3.02), extracellular volume 1.64 (95% CI 0.87-2.42), LGE percentage 1.30 (95% CI 0.95-1.64), T1 mapping time 1.18 (95% CI 0.35-2.01), T2 ratio 1.17 (95% CI 0.80-1.54), and EGE ratio 0.93 (95% CI 0.66-1.19). Prolonged T1 mapping time had the highest sensitivity (82%), pericardial effusion had the highest specificity (99%). Baseline LV dysfunction and the presence of LGE were predictive of major adverse cardiac events. The results support integration of parametric mapping criteria in the diagnostic criteria for myocarditis. The presence of baseline LV dysfunction and LGE predict patients at higher risk of adverse events.

Comparison of Original and 2018 Lake Louise Criteria for Diagnosis of Acute Myocarditis: Results of a Validation Cohort

PURPOSE

To compare the diagnostic performance of the original Lake Louise criteria (LLC) and the 2018 LLC for the diagnosis of acute myocarditis and simultaneously validate previously reported cutoff values for parametric mapping techniques.

MATERIALS AND METHODS

A total of 40 patients with acute myocarditis and 26 control participants underwent cardiac MRI. Cardiac MRI protocol allowed for assessment of T2 signal intensity ratio, early gadolinium enhancement ratio, late gadolinium enhancement, T1 relaxation times, extracellular volume fraction, and T2 relaxation times. The original and the 2018 LLC were assessed, and differences between sensitivities and specificities were calculated with the McNemar test.

RESULTS

The 2018 LLC yielded a sensitivity of 87.5% (95% confidence interval [CI]: 73.9%, 94.5%) and a specificity of 96.2% (95% CI: 81.1%, 99.3%). The original LLC had a sensitivity of 72.5% (95% CI: 57.2%, 83.9%) and a specificity of 96.2% (95% CI: 81.1%, 99.3%). Sensitivity of the 2018 LLC was significantly higher compared with the sensitivity of original LLC (P = .031). No differences in specificity were observed between both scores (P = .999).

CONCLUSION

Multiparametric cardiac MRI has a high diagnostic value for the diagnosis of patients clinically suspected of having acute myocarditis. The 2018 LLC further improve the diagnostic performance of cardiac MRI by increasing its sensitivity. An implementation of the new score into routine diagnostic protocols should be considered.© RSNA, 2019See also the commentary by Gutberlet and Lücke in this issue.Supplemental material is available for this article.

Cardiac T1 mapping: Techniques and applications

A key advantage of cardiac magnetic resonance (CMR) imaging over other cardiac imaging modalities is the ability to perform detailed tissue characterization. CMR techniques continue to evolve, with advanced imaging sequences being developed to provide a reproducible, quantitative method of tissue interrogation. The T₁ mapping technique, a pixel-by-pixel method of quantifying T₁ relaxation time of soft tissues, has been shown to be promising for characterization of diseased myocardium in a wide variety of cardiomyopathies. In this review, we describe the basic principles and common techniques for T₁ mapping and its use for native T₁ , postcontrast T₁ , and extracellular volume mapping. We will review a wide range of clinical applications of the technique that can be used for identification and quantification of myocardial edema, fibrosis, and infiltrative diseases with illustrative clinical examples. In addition, we will explore the current limitations of the technique and describe some areas of ongoing development. Level of Evidence: 5 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:1336-1356.

CMR for Identifying the Substrate of Ventricular Arrhythmia in Patients With Normal Echocardiography

OBJECTIVES

This study sought to determine whether cardiac magnetic resonance (CMR) may identify structural heart disease (SHD) in patients with ventricular arrhythmia who had echocardiography ruled out pathological findings.

BACKGROUND

Approximately one-half of sudden cardiac deaths are attributable to malignant VA. Echocardiography is commonly used to identify SHD that is the most frequent substrate of VA.

METHODS

A single-center prospective study was conducted in consecutive patients with significant VA, categorized as >1,000 but <10,000 ventricular ectopic beats [VEBs]/24 h; ≥10,000 VEBs/24 h; nonsustained ventricular tachycardia, sustained ventricular tachycardia, or a history of resuscitated cardiac arrest, and no pathological findings at echocardiography, requiring a clinically indicated CMR. Primary endpoint was CMR detection of SHD. Secondary endpoints were a composite of CMR detection of SHD and abnormal findings not specific for a definite SHD diagnosis.

RESULTS

A total of 946 patients were enrolled (mean 41 ± 16 years of age; 64% men). CMR studies were used to diagnose SHD in 241 patients (25.5%) and abnormal findings not specific for a definite SHD diagnosis in 187 patients (19.7%). Myocarditis (n = 91) was the more frequent disease, followed by arrhythmogenic cardiomyopathy (n = 55), dilated cardiomyopathy (n = 39), ischemic heart disease (n = 22), hypertrophic cardiomyopathy (n = 13), congenital cardiac disease (n = 10), left ventricle noncompaction (n = 5), and pericarditis (n = 5). The strongest univariate and multivariate predictors of SHD on CMR images were chest pain (odds ratios [OR]: 2.52 and 2.38, respectively) and sustained ventricular tachycardia (ORs: 2.67 and 2.23, respectively).

CONCLUSIONS

SHD was able to be identified on CMR imaging in a sizable number of patients with significant VA and completely normal echocardiography. Chest pain and sustained ventricular tachycardia were the strongest predictors of positive CMR imaging results.

Diagnostic performance of cardiovascular magnetic resonance native T1 and T2 mapping in pediatric patients with acute myocarditis

BACKGROUND

Multiple studies in adult patients suggest that tissue mapping performed by cardiovascular magnetic resonance (CMR) has excellent diagnostic accuracy in acute myocarditis, however, these techniques have not been studied in depth in children.

METHODS

CMR data on 23 consecutive pediatric patients from 2014 to 2017 with a clinical diagnosis of acute myocarditis were retrospectively analyzed and compared to 39 healthy controls. The CMR protocol included native T1, T2, and extracellular volume fraction (ECV) in addition to standard Lake Louise Criteria (LLC) parameters on a 1.5 T scanner.

RESULTS

Mean global values for novel mapping parameters were significantly elevated in patients with clinically suspected acute myocarditis compared to controls, with native T1 1098 ± 77 vs 990 ± 34 ms, T2 52.8 ± 4.6 ms vs 46.7 ± 2.6 ms, and ECV 29.8 ± 5.1% vs 23.3 ± 2.6% (all p-values < 0.001). Ideal cutoff values were generated using corresponding ROC curves and were for global T1 1015 ms (AUC 0.936, sensitivity 91%, specificity 86%), for global T2 48.5 ms (AUC 0.908, sensitivity 91%, specificity 74%); and for ECV 25.9% (AUC 0.918, sensitivity 86%, specificity 89%). While the diagnostic yield of the LLC was 57% (13/23) in our patient cohort, 70% (7/10) of patients missed by the LLC demonstrated abnormalities across all three global mapping parameters (native T1, T2, and ECV) and another 20% (2/10) of patients demonstrated at least one abnormal mapping value.

CONCLUSIONS

Similar to findings in adults, pediatric patients with acute myocarditis demonstrate abnormal CMR tissue mapping values compared to controls. Furthermore, we found CMR parametric mapping techniques measurably increased CMR diagnostic yield when compared with conventional LLC alone, providing additional sensitivity and specificity compared to historical references. Routine integration of these techniques into imaging protocols may aid diagnosis in children.

The Role of Contrast-Enhanced Cardiac Magnetic Resonance in the Assessment of Patients with Malignant Ventricular Arrhythmias

Cardiac magnetic resonance (CMR) imaging has gained significant traction as an imaging modality of choice in the evaluation of individuals with, or at risk for, heart failure. Ventricular arrhythmias, often malignant, may be sequelae of heart failure and arise from fibrosis. Late gadolinium enhancement evaluation by CMR has become a preferred modality to assess individuals at risk for malignant ventricular arrhythmias. A spectrum of various pathologies that predispose individuals to malignant ventricular arrhythmias, as well as the usefulness of CMR in their identification and prognostication, are reviewed.

Natural History of Myocardial Injury and Chamber Remodeling in Acute Myocarditis

Background:

Cardiovascular magnetic resonance (CMR) imaging is commonly used to diagnose acute myocarditis. However, the natural history of CMR-based tissue markers and their association with left ventricular recovery is poorly explored. We prospectively investigated the natural history of CMR-based myocardial injury and chamber remodeling over 12 months in patients with suspected acute myocarditis.

Methods:

One hundred patients with suspected acute myocarditis were enrolled. All underwent CMR evaluations at baseline and 12 months, inclusive of T2 and late gadolinium enhancement. Blinded quantitative analyses compared left ventricular chamber volumes, function, myocardial edema, and necrosis at each time point using predefined criteria. The predefined primary outcomes were improvement in left ventricular ejection fraction ≥10% and improvement in the indexed left ventricular end diastolic volume ≥10% at 12 months.

Results:

The mean age was 39.9±14.5 years (82 male) with baseline left ventricular ejection fraction of 57.1±11.2%. A total of 72 patients (72%) showed late gadolinium enhancement at baseline with 57 (57%) having any T2 signal elevation. Left ventricular volumes and EF improved significantly at 12 months. Global late gadolinium enhancement extent dropped from 8.5±9.2% of left ventricular mass to 3.0±5.2% ( P =0.0001) with prevalence of any late gadolinium enhancement dropping to 48%. Reductions in global T2 signal ratio occurred at 12 months (1.85±0.3 to 1.56±0.2; P =0.0001) with prevalence of T2 ratio ≥2.0 dropping to 7%. Neither marker provided associations with the primary outcomes.

Conclusions:

In clinically suspected acute myocarditis, significant reductions in tissue injury markers occur during the first 12 months of convalescence. Neither the presence nor extent of the investigated CMR-based tissue injury markers were predictive of our pre-defined function or remodeling outcomes at 12 months in this referral population.

Cocaine Abuse: An Attack to the Cardiovascular System-Insights from Cardiovascular MRI

Cocaine is the most commonly used illicit drug in the European Union. Its cardiac effects are numerous and diverse, both in acute and chronic abuse, and include myocardial infarction, myocarditis, catecholamine-induced cardiomyopathy, and chronic cardiomyopathy (subclinical, hypertrophic, and dilated phases). Their clinical manifestations are vastly overlapping, and differential diagnosis should be performed using a thorough diagnostic workup featuring clinical history, laboratory tests, electrocardiography, stress test, noninvasive imaging modalities, and coronary angiography. Cardiac MRI has the unique ability of in vivo tissue characterization. This unique feature can play a pivotal role in the differential diagnosis through proper characterization of the myocardial tissue. Especially in acute settings, cardiac MRI makes it possible to distinguish between cocaine-induced myocardial infarction, cocaine-induced myocarditis, and catecholamine-induced cardiomyopathy. Conversely, in chronic cardiomyopathy, cardiac MRI permits evaluation of ventricular function and myocardial tissue, allowing the investigation of the underlying cause. On the one hand, assessing the ventricular function permits differentiation among subclinical, hypertrophic, and dilated phases of chronic cardiomyopathy; on the other hand, cardiac MRI could classify the causes underlying remodeling, including chronic ischemic injury, chronic myocarditis, and cardiac motion impairment. This review analyzes the relationship between pathophysiology, histology, and disease using the existing literature on cardiac MRI cocaine abuse evaluation. © RSNA, 2019.

Myocarditis in Athletes Is a Challenge: Diagnosis, Risk Stratification, and Uncertainties

Presentation of myocarditis in athletes is heterogeneous and establishing the diagnosis is challenging with no current uniform clinical gold standard. The combined information from symptoms, electrocardiography, laboratory testing, echocardiography, cardiac magnetic resonance imaging, and in certain cases endomyocardial biopsy helps to establish the diagnosis. Most patients with myocarditis recover spontaneously; however, athletes may be at higher risk of adverse cardiac events. Based on scarce evidence and mainly autopsy studies and expert's opinions, current recommendations generally advise abstinence from competitive sports ranging from a minimum of 3 to 6 months. However, the dilemma poses that (un)necessary prolonged disqualification of athletes to avoid adverse cardiac events can cause considerable disruption to training schedules and tournament preparation and lead to a decline in performance and ability to compete. Therefore, better risk stratification tools are imperatively needed. Using latest available data, this review contrasts existing recommendations and presents a new proposed diagnostic flowchart putting a greater focus on the use of cardiac magnetic resonance imaging in athletes with suspected myocarditis. This may enable cardiac caregivers to counsel athletes with suspected myocarditis more systematically and furthermore allow for pooling of more unified data. To modify recommendations regarding sports behavior in athletes with myocarditis, evidence, based on large multicenter registries including cardiac magnetic resonance imaging and endomyocardial biopsy, is needed. In the future, physicians might rely on combined novel risk stratification methods, by implementing both noninvasive and invasive tissue characterization methods.

Cardiotoxicity of Immune Checkpoint Inhibitors

PURPOSE OF REVIEW

Immunotherapies, particularly immune checkpoint inhibitors (ICI), are revolutionary cancer therapies being increasingly applied to a broader range of cancers. Our understanding of the mechanism, epidemiology, diagnosis, and treatment of cardiotoxicity related to immunotherapies remains limited. We aim to synthesize the limited current literature on cardiotoxicity of ICIs and to share our opinions on the diagnosis and treatment of this condition.

RECENT FINDINGS

The incidence of ICI-associated myocarditis ranges from 0.1 to 1%. Patients with ICI-associated myocarditis often have a fulminant course with a case fatality rate of 25-50%. The diagnosis of this condition poses many challenges because independently a normal electrocardiogram, biomarkers, or a preserved left ventricular function do not rule out ICI-associated myocarditis. Endomyocardial biopsy should be pursued when clinical suspicion remains despite normal non-invasive tests. Data on optimal screening and surveillance tools are lacking. Cessation of ICIs, combined with high dose corticosteroids and other immunosuppressant approaches are the cornerstones of the treatment of ICI-associated myocarditis. This condition may recur when patients are re-challenged with these agents and the decision to resume ICIs should be made through a multidisciplinary discussion. Immunotherapies have changed the landscape of cancer treatment. Recognizing and managing cardiotoxicity related to ICIs is of critical importance. Our understanding of ICI-cardiotoxicity has improved, but large information gaps remain for further research. Due to the high case fatality rate, any type of cardiac symptoms or signs in a patient who has recently started an ICI should prompt consideration of ICI-cardiotoxicity.

The Role of Cardiac Magnetic Resonance Imaging to Detect Cardiac Toxicity From Cancer Therapeutics

PURPOSE OF REVIEW

The emerging complexity of cardiac toxicity caused by cancer therapies has created demand for more advanced non-invasive methods to better evaluate cardiac structure, function, and myocardial tissue characteristics. Cardiac magnetic resonance imaging meets these needs without exposure to ionizing radiation, and with superior spatial resolution.

RECENT FINDINGS

Special applications of cardiac magnetic resonance (CMR) to assess for cancer therapy-induced cardiac toxicity include the detection of subclinical LV dysfunction through novel methods of measuring myocardial strain, detection of microcirculatory dysfunction, identification of LV and LA fibrosis, and more sensitive detection of inflammation caused by immune checkpoint inhibitors. CMR plays a significant role in the non-invasive workup of cardiac toxicity from cancer therapies, with recent advancements in the field that have opened avenues for further research and development.

Myocarditis in Humans and in Experimental Animal Models

Myocarditis is defined as an inflammation of the cardiac muscle. In humans, various infectious and non-infectious triggers induce myocarditis with a broad spectrum of histological presentations and clinical symptoms of the disease. Myocarditis often resolves spontaneously, but some patients develop heart failure and require organ transplantation. The need to understand cellular and molecular mechanisms of inflammatory heart diseases led to the development of mouse models for experimental myocarditis. It has been shown that pathogenic agents inducing myocarditis in humans can often trigger the disease in mice. Due to multiple etiologies of inflammatory heart diseases in humans, a number of different experimental approaches have been developed to induce myocarditis in mice. Accordingly, experimental myocarditis in mice can be induced by infection with cardiotropic agents, such as coxsackievirus B3 and protozoan parasite Trypanosoma cruzi or by activating autoimmune responses against heart-specific antigens. In certain models, myocarditis is followed by the phenotype of dilated cardiomyopathy and the end stage of heart failure. This review describes the most commonly used mouse models of experimental myocarditis with a focus on the role of the innate and adaptive immune systems in induction and progression of the disease. The review discusses also advantages and limitations of individual mouse models in the context of the clinical manifestation and the course of the disease in humans. Finally, animal-free alternatives in myocarditis research are outlined.

Connection between the heart and the gut

Clinical introduction

A 45-year-old man with ulcerative colitis was admitted with bloody diarrhoea and chest pain. Inflammatory markers and high-sensitivity troponin were elevated (C reactive protein 57 mg/L, white cell count 10.65×10⁹/L, neutrophil 6.6×10⁹/L, Troponin-I 663 mmol/L). The ECG showed inferior ST-elevation. Urgent coronary angiography revealed unobstructed coronary arteries. Inpatient cardiovascular magnetic resonance (CMR) was arranged to determine the aetiology of the myocardial infarction with non-obstructive coronary arteries. The imaging protocol at 1.5 T included balanced steady-state free precession cine images, T2-weighted oedema sequences, and early and late gadolinium enhancement (LGE). Native T1 and T2 mapping images provided advanced tissue characterisation (figure 1).

Question

What is the most likely diagnosis based on the MRI findings? 

Multiple embolic myocardial infarctions in the right coronary artery territory.

Acute autoimmune myocarditis.

Cardiac sarcoidosis.

Stress (Takotsubo) cardiomyopathy.

Multiple embolic myocardial infarctions in the left circumflex coronary artery territory.

Editor-in-Chief's Top Picks From 2018

Each week, I record audio summaries for every article in JACC, as well as an issue summary. Although this process is quite time-consuming, I have become familiar with every paper that we publish. Thus, I have personally selected the top 100 papers (both Original Investigations and Review Articles) from 15 distinct specialties each year. In addition to my personal choices, I have included papers that have been the most accessed or downloaded on our websites, as well as those selected by the JACC Editorial Board members. In order to present the full breadth of this important research in a consumable fashion, we will present these abstracts in this issue of JACC. The highlights comprise the following sections: Basic & Translational Research, Cardiac Failure, Cardiomyopathies/Myocardial & Pericardial Diseases, Cardio-oncology, Congenital Heart Disease, Coronary Disease & Interventions, CVD Prevention & Health Promotion, CV Medicine & Society, Hypertension, Imaging, Metabolic & Lipid Disorders, Rhythm Disorders, Valvular Heart Disease, and Vascular Medicine (1-100).