Imaging of Inflammation in Unexplained Cardiomyopathy

Arrhythmogenic Potential of Myocardial Edema: The Interstitial Osmolality Induces Spiral Waves and Multiple Excitation Wavelets

Myocardial edema is a common symptom of pathological processes in the heart, causing aggravation of cardiovascular diseases and leading to irreversible myocardial remodeling. Patient-based studies show that myocardial edema is associated with arrhythmias. Currently, there are no studies that have examined how edema may influence changes in calcium dynamics in the functional syncytium. We performed optical mapping of calcium dynamics on a monolayer of neonatal rat cardiomyocytes with Fluo-4. The osmolality of the solutions was adjusted using the NaCl content. The initial Tyrode solution contained 140 mM NaCl (1T) and the hypoosmotic solutions contained 105 (0.75T) and 70 mM NaCl (0.5T). This study demonstrated a sharp decrease in the calcium wave propagation speed with a decrease in the solution osmolality. The successive decrease in osmolality also showed a transition from a normal wavefront to spiral wave and multiple wavelets of excitation with wave break. Our study demonstrated that, in a cellular model, hypoosmolality and, as a consequence, myocardial edema, could potentially lead to fatal ventricular arrhythmias, which to our knowledge has not been studied before. At 0.75T spiral waves appeared, whereas multiple wavelets of excitation occurred in 0.5T, which had not been recorded previously in a two-dimensional monolayer under conditions of cell edema without changes in the pacing protocol.

STING-Targeted PET Imaging for Specific Detection and Therapeutic Monitoring of Myocarditis

Imaging strategies for the specific detection and therapeutic monitoring of myocarditis are still lacking. Stimulator of interferon genes (STING) is a signal transduction molecule involved in an innate immune response. Here, we evaluated the feasibility of the recently developed STING-targeted radiotracer [18F]FBTA for positron emission tomography (PET) imaging to detect myocardial inflammation and monitor treatment in myocarditis mice. [18F]FBTA-PET imaging was performed in myocarditis mice and normal mice to verify the specificity of [18F]FBTA for the diagnosis of myocarditis. We also performed PET imaging in mice with myocarditis treated to verify the ability of [18F]FBTA in therapeutic monitoring. The expression of STING and inflammatory cell types was confirmed by flow cytometry and immunohistochemistry. [18F]FDG-PET imaging of myocarditis was used as a contrast. [18F]FBTA-PET imaging showed that the average radioactive uptake was significantly higher in the hearts of the myocarditis group than in the control group. STING was highly overexpressed in cardiac inflammatory cells, including macrophages, dendritic cells (DCs), and T cells. However, there was no significant difference in cardiac radiotracer uptake of [18F]FDG between the myocarditis group and the control group. Moreover, cardiac uptake of [18F]FBTA was significantly reduced in cyclosporin A-treated myocarditis mice and myocardial STING expression was also significantly reduced after the treatment. Overall, we showed that a STING-targeted PET tracer [18F]FBTA can be used to monitor changes in the inflammatory microenvironment in myocarditis. Besides, [18F]FBTA-PET is also suitable for real-time monitoring of myocarditis treatment, representing a promising diagnostic and therapeutic monitoring approach for myocarditis.

Mechanisms of Myocardial Edema Development in CVD Pathophysiology

Myocardial edema is the excess accumulation of fluid in the myocardial interstitium or cardiac cells that develops due to changes in capillary permeability, loss of glycocalyx charge, imbalance in lymphatic drainage, or a combination of these factors. Today it is believed that this condition is not only a complication of cardiovascular diseases, but in itself causes aggravation of the disease and increases the risks of adverse outcomes. The study of molecular, genetic, and mechanical changes in the myocardium during edema may contribute to the development of new approaches to the diagnosis and treatment of this condition. This review was conducted to describe the main mechanisms of myocardial edema development at the molecular and cellular levels and to identify promising targets for the regulation of this condition based on articles cited in Pubmed up to January 2024.

Vascular adhesion protein-1-targeted PET imaging in autoimmune myocarditis

BACKGROUND

Vascular adhesion protein-1 (VAP-1) is an adhesion molecule and primary amine oxidase, and Gallium-68-labeled 1,4,7,10-tetraazacyclododecane-N,N',N″,N‴-tetra-acetic acid conjugated sialic acid-binding immunoglobulin-like lectin 9 motif containing peptide ([68Ga]Ga-DOTA-Siglec-9) is a positron emission tomography (PET) tracer targeting VAP-1. We evaluated the feasibility of PET imaging with [68Ga]Ga-DOTA-Siglec-9 for the detection of myocardial lesions in rats with autoimmune myocarditis.

METHODS

Rats (n = 9) were immunized twice with porcine cardiac myosin in complete Freund's adjuvant. Control rats (n = 6) were injected with Freund's adjuvant alone. On day 21, in vivo PET/computed tomography (CT) imaging with [68Ga]Ga-DOTA-Siglec-9 was performed, followed by ex vivo autoradiography, histology, and immunohistochemistry of tissue sections. In addition, myocardial samples from three patients with cardiac sarcoidosis were studied.

RESULTS

[68Ga]Ga-DOTA-Siglec-9 PET/CT images of immunized rats showed higher uptake in myocardial lesions than in myocardium outside lesions (SUVmean, 0.5 ± 0.1 vs 0.3 ± 0.1; P = .003) or control rats (SUVmean, 0.2 ± 0.03; P < .0001), which was confirmed by ex vivo autoradiography of tissue sections. Immunohistochemistry showed VAP-1-positive staining in lesions of rats with myocarditis and in patients with cardiac sarcoidosis.

CONCLUSION

VAP-1-targeted [68Ga]Ga-DOTA-Siglec-9 PET is a potential novel technique for the detection of myocardial lesions.

Novel Imaging Approaches to Cardiac Manifestations of Systemic Inflammatory Diseases: JACC Scientific Statement

Derangements in the innate and adaptive immune responses observed in systemic inflammatory syndromes contributes to unique elevated atherosclerotic risk and incident cardiovascular disease. Novel multimodality imaging techniques may improve diagnostic precision for the screening and monitoring of disease activity. The integrated application of these technologies lead to earlier diagnosis and noninvasive monitoring of cardiac involvement in systemic inflammatory diseases that will aid in preclinical studies, enhance patient selection, and provide surrogate endpoints in clinical trials, thereby improving clinical outcomes. We review the common cardiovascular manifestations of immune-mediated systemic inflammatory diseases and address the clinical and investigational role of advanced multimodality cardiac imaging.

Biomarkers in Acute Myocarditis and Chronic Inflammatory Cardiomyopathy: An Updated Review of the Literature

Myocarditis is a disease caused by cardiac inflammation that can progress to dilated cardiomyopathy, heart failure, and eventually death. Several etiologies, including autoimmune, drug-induced, and infectious, lead to inflammation, which causes damage to the myocardium, followed by remodeling and fibrosis. Although there has been an increasing understanding of pathophysiology, early and accurate diagnosis, and effective treatment remain challenging due to the high heterogeneity. As a result, many patients have poor prognosis, with those surviving at risk of long-term sequelae. Current diagnostic methods, including imaging and endomyocardial biopsy, are, at times, expensive, invasive, and not always performed early enough to affect disease progression. Therefore, the identification of accurate, cost-effective, and prognostically informative biomarkers is critical for screening and treatment. The review then focuses on the biomarkers currently associated with these conditions, which have been extensively studied via blood tests and imaging techniques. The information within this review was retrieved through extensive literature research conducted on major publicly accessible databases and has been collated and revised by an international panel of experts. The biomarkers discussed in the article have shown great promise in clinical research studies and provide clinicians with essential tools for early diagnosis and improved outcomes.

Phenotyping of giant cell myocarditis versus cardiac sarcoidosis using cardiovascular magnetic resonance

BACKGROUND

Giant cell myocarditis (GCM) and cardiac sarcoidosis (CS) are rare inflammatory diseases of the myocardium with poor prognosis. Little is known about the cardiovascular magnetic resonance (CMR) appearance of GCM and the methods ability to distinguish the two rare entities from one another.

METHODS

We assessed a total of 40 patients with endomyocardial biopsy-proven GCM (n = 14) and CS (n = 26) concerning their clinical and CMR appearance in a blinded manner.

RESULTS

Patients with GCM and CS were of similar median age (55 vs 56 years), and a male predominance was observed in both groups. In GCM, median levels of troponin T (313 vs 31 ng/L, p < 0.001), and natriuretic peptides (6560 vs 676 pg/mL, p < 0.001) were higher than in CS, and the clinical outcome worse (p = 0.04). On CMR imaging, the observed alterations of left and right ventricular (LV/RV) dimensions and function were similar. GCM showed multifocal LV late gadolinium enhancement (LGE) with a similar longitudinal, circumferential, and radial distribution as in CS, including suggested signature imaging biomarkers of CS like the "hook sign" (71% vs 77%, p = 0.702). The median LV LGE enhanced volume was 17% and 22% in GCM and CS (p = 0.150), respectively. The number of RV segments with pathologically increased T2 signal and/or LGE were most extensive in GCM.

CONCLUSIONS

The CMR appearance of both GCM and CS is highly similar, making the differentiation between the two rare entities solely based on CMR challenging. This stands in contrast to the clinical appearance, which seems to be more severe in GCM.

Echocardiography in inflammatory heart disease: A comparison of giant cell myocarditis, cardiac sarcoidosis, and acute non-fulminant myocarditis

Background

Giant cell myocarditis (GCM) and cardiac sarcoidosis (CS) are, in contrast to acute non-fulminant myocarditis (ANFM), rare inflammatory diseases of the myocardium with poor prognosis. Although echocardiography is the first-line diagnostic tool in these patients, their echocardiographic appearance has so far not been systematically studied.

Methods

We assessed a total of 71 patients with endomyocardial biopsy-proven GCM (n = 21), and CS (n = 25), as well as magnetic resonance-verified ANFM (n = 25). All echocardiographic examinations, performed upon clinical presentation, were reanalysed according to current guidelines including a detailed assessment of right ventricular (RV) dysfunction.

Results

In comparison with ANFM, patients with either GCM or CS were older (mean age (±SD) 55 ± 12 or 53 ± 8 vs 25 ± 8 years), more often of female gender (52% or 24% vs 8%), had more severe clinical symptoms and higher natriuretic peptide levels. For both GCM and CS, echocardiography revealed more frequently signs of left ventricular (LV) dysfunction in form of a reduced ejection fraction (p < 0.001), decreased cardiac index (p < 0.001) and lower global longitudinal strain (p < 0.001) in contrast to ANFM. The most prominent increase in LV end-diastolic volume index was observed in CS. In addition, RV dysfunction was more frequently found in both GCM and CS than in ANFM (p = 0.042).

Conclusions

Both GCM and CS have an echocardiographic and clinical appearance that is distinct from ANFM. However, the method cannot further differentiate between the two rare entities. Consequently, echocardiography can strengthen the initial clinical suspicion of a more severe form of myocarditis, thus warranting a more rigorous clinical work-up.

Cardiac magnetic resonance in giant cell myocarditis: a matched comparison with cardiac sarcoidosis

AIMS

Giant cell myocarditis (GCM) is an inflammatory cardiomyopathy akin to cardiac sarcoidosis (CS). We decided to study the findings of GCM on cardiac magnetic resonance (CMR) imaging and to compare GCM with CS.

METHODS AND RESULTS

CMR studies of 18 GCM patients were analyzed and compared with 18 CS controls matched for age, sex, left ventricular (LV) ejection fraction and presenting cardiac manifestations. The analysts were blinded to clinical data. On admission, the duration of symptoms (median) was 0.2 months in GCM vs. 2.4 months in CS (P = 0.002), cardiac troponin T was elevated (>50 ng/L) in 16/17 patients with GCM and in 2/16 with CS (P < 0.001), their respective median plasma B-type natriuretic propeptides measuring 4488 ng/L and 1223 ng/L (P = 0.011). On CMR imaging, LV diastolic volume was smaller in GCM (177 ± 32 mL vs. 211 ± 58 mL, P = 0.014) without other volumetric or wall thickness measurements differing between the groups. Every GCM patient had multifocal late gadolinium enhancement (LGE) in a distribution indistinguishable from CS both longitudinally, circumferentially, and radially across the LV segments. LGE mass averaged 17.4 ± 6.3% of LV mass in GCM vs 25.0 ± 13.4% in CS (P = 0.037). Involvement of insertion points extending across the septum into the right ventricular wall, the "hook sign" of CS, was present in 53% of GCM and 50% of CS.

CONCLUSION

In GCM, CMR findings are qualitatively indistinguishable from CS despite myocardial inflammation being clinically more acute and injurious. When matched for LV dysfunction and presenting features, LV size and LGE mass are smaller in GCM.

Endomyocardial biopsy-confirmed myocarditis and inflammatory cardiomyopathy: clinical profile and prognosis

INTRODUCTION AND OBJECTIVES

Endomyocardial biopsy (EMB) is the only technique able to establish an etiological diagnosis of myocarditis or inflammatory cardiomyopathy (ICM). The aim of this study was to analyze the clinical profile, outcomes, and prognostic factors of patients with suspected myocarditis/ICM undergoing EMB.

METHODS

We retrospectively analyzed the clinical characteristics, histological findings, and follow-up data of all patients with suspected myocarditis or ICM who underwent EMB between 1997 and 2019 in a Spanish tertiary hospital. The diagnostic yield was compared using the Dallas criteria vs immunohistochemical criteria (IHC).

RESULTS

A total of 99 patients underwent EMB (67% male; mean age, 42±15 years; mean left ventricular ejection fraction [LVEF], 34%±14%). Myocarditis or ICM was confirmed in 28% with application of the Dallas criteria and in 54% with the IHC criteria (P <.01). Lymphocytic myocarditis was diagnosed in 47 patients, eosinophilic myocarditis in 6, sarcoidosis in 3, and giant cell myocarditis in 1 patient. After a median follow-up of 18 months, 23 patients (23%) required heart transplant (HTx), a left ventricular assist device (LVAD), and/or died. Among the patients with IHC-confirmed myocarditis, 21% required HTx/LVAD or died vs 7% of those without inflammation (P=.056). The factors associated with a worse prognosis were baseline LVEF ≤ 30%, left ventricular end-diastolic diameter ≥ 60mm, and NYHA III-IV, especially in the presence of inflammation.

CONCLUSIONS

EMB allows an etiological diagnosis in more than half of patients with suspected myocarditis/ICM when IHC techniques are used. IHC-confirmed inflammation adds prognostic value and helps to identify patients with a higher probability of developing complications.

The role of PET/CT in connective tissue disorders: systemic sclerosis, Sjögren's syndrome and systemic lupus erythematosus

Advanced imaging techniques are needed to help clinicians in the diagnosis, in the choice of the right time for therapeutic interventions or for modifications and monitoring of treatment response in patients with autoimmune connective tissue diseases. Nuclear medicine imaging, especially PET/CT and PET/MRI, may play an important role in detecting disease activity, assessing early treatment response as well as in clarifying the complex mechanisms underlying systemic sclerosis, Sjögren's syndrome or systemic lupus erythematosus. In addition, [¹⁸F]FDG PET/CT may help in excluding or detecting coexisting malignancies. Other more specific radiopharmaceuticals are being developed and investigated, targeting specific cells and molecules involved in connective tissue diseases. Further larger studies with standardized imaging protocol and image interpretation are strongly required before including PET/CT in the diagnostic work-up of subsets of patients with autoimmune connective tissue diseases.

Long COVID and the cardiovascular system - elucidating causes and cellular mechanisms in order to develop targeted diagnostic and therapeutic strategies: A joint Scientific Statement of the ESC Working Groups on Cellular Biology of the Heart and Myocardial & Pericardial Diseases

Long COVID has become a world-wide, non-communicable epidemic, caused by long-lasting multi-organ symptoms that endure for weeks or months after SARS-CoV-2 infection has already subsided. This scientific document aims to provide insight into the possible causes and therapeutic options available for the cardiovascular manifestations of long COVID. In addition to chronic fatigue, which is a common symptom of long COVID, patients may present with chest pain, ECG abnormalities, postural orthostatic tachycardia, or newly developed supraventricular or ventricular arrhythmias. Imaging of the heart and vessels has provided evidence of chronic, post-infectious peri-myocarditis with consequent left or right ventricular failure, arterial wall inflammation or micro-thrombosis in certain patient populations. Better understanding of the underlying cellular and molecular mechanisms of long COVID will aid in the development of effective treatment strategies for its cardiovascular manifestations. A number of mechanisms have been proposed, including those involving direct effects on the myocardium, micro-thrombotic damage to vessels or endothelium, or persistent inflammation. Unfortunately, existing circulating biomarkers, coagulation and inflammatory markers, are not highly predictive for either the presence or outcome of long COVID when measured 3 months after SARS-CoV-2 infection. Further studies are needed to understand underlying mechanisms, identify specific biomarkers and guide future preventive strategies or treatments to address long COVID and its cardiovascular sequelae.

From trivial to severe arrhythmias: the diagnostic role of multimodality imaging in inflammatory cardiomyopathy through a case series

Background 

The diagnosis of inflammatory cardiomyopathy remains challenging in cases presenting with arrhythmia as sole manifestation. An early diagnosis is critical as it may prevent life-threatening complications such as sudden cardiac death and atrioventricular block (AVB). The diagnostic workup of suspected cases includes multimodality imaging that requires an adequate interpretation in order to limit the risk of overdiagnosis.

Case summary 

Herein, we report three cases presenting with various new-onset arrhythmias. The first patient was admitted for a third-degree AVB. The second patient suffered from a supraventricular tachycardia which degenerated into ventricular fibrillation. The third case was investigated for symptomatic premature ventricular complexes. No apparent heart disease was observed on standard exams (clinical, biological examinations, and echocardiography). However, cardiac magnetic resonance imaging (MRI) and nuclear imaging (68Ga-DOTATOC and/or 18F-FDG PET/CT) suggested an inflammatory substrate that seemed to correlate with the arrhythmic phenotype. Cardiac inflammation disappeared on immunotherapy for the first case and spontaneously for the third case.

Discussion 

These cases emphasize the incremental diagnostic yield of multimodality imaging to highlight myocardial inflammation. Nuclear imaging modalities may complement MRI by enabling the detection of active inflammation. The 18F-FDG PET/CT is well established for the diagnosis of cardiac sarcoidosis but its role remains to be clarified for the diagnosis of myocarditis. An alternative radiotracer, 68Ga-DOTATOC, appears promising by overcoming the main limitation of 18F-FDG but its specificity is not yet well established. The role of functional investigations is discussed as well as the benefit of immunosuppressive treatments.

Inflammatory Cardiomyopathy: Case-based Review on Clinical Presentation, Diagnosis, and Management

Inflammatory cardiomyopathy is a broad term encompassing any disease leading to myocardial inflammation with associated cardiac dysfunction. While endomyocardial biopsy remains the gold standard for diagnosis, noninvasive imaging techniques, such as cardiac magnetic resonance imaging and positron emission tomography, have become powerful tools to facilitate the identification of underlying myocardial inflammation. This review presents a series of clinical cases with some common etiologies of inflammatory cardiomyopathy, including diagnosis and management.

SARS-CoV-2 Myocarditis: Insights Into Incidence, Prognosis, and Therapeutic Implications

PURPOSE OF REVIEW

In coronavirus disease 2019 (COVID-19), myocardial injury occurs frequently in severe or critically ill hospitalized patients, yet myocarditis is much less common. In this context, revisiting the definition of myocarditis is appropriate with a specific focus on diagnostic and management considerations in patients infected with SARS-CoV-2.

RECENT FINDINGS

Pathologic cardiac specimens from patients with COVID-19 suggest a mixed inflammatory response involving lymphocytes and macrophages, and importantly, cellular injury occurs predominantly at the level of pericytes and endothelial cells, less often involving direct myocyte necrosis. In COVID-19, the diagnosis of myocarditis has understandably been based predominantly on clinical criteria, and the number of patients with clinically suspected myocarditis who would meet diagnostic histological criteria is unclear. Echocardiography and cardiac magnetic resonance are important diagnostic tools, although the prognostic implications of abnormalities are still being defined. Importantly, SARS-CoV2 myocarditis should be diagnosed within an appropriate clinical context and should not be based on isolated imaging findings. Therapies in COVID-19 have focused on the major clinical manifestation of pneumonia, but the promotion of viral clearance early in the disease could prevent the development of myocarditis, and further study of immunosuppressive therapies once myocarditis has developed are indicated. A strict and uniform approach is needed to diagnose myocarditis due to SARS-CoV-2 to better understand the natural history of this disease and to facilitate evaluation of potential therapeutic interventions. A methodological approach will also better inform the incidence of COVID-19 associated myocarditis and potential long-term health effects.

Multi-Modality Imaging for the Identification of Arrhythmogenic Substrates Prior to Electrophysiology Studies

Noninvasive cardiac imaging is crucial for the characterization of patients who are candidates for cardiac ablations, for both procedure planning and long-term management. Multimodality cardiac imaging can provide not only anatomical parameters but even more importantly functional information that may allow a better risk stratification of cardiac patients. Moreover, fusion of anatomical and functional data derived from noninvasive cardiac imaging with the results of endocavitary mapping may possibly allow a better identification of the ablation substrate and also avoid peri-procedural complications. As a result, imaging-guided electrophysiological procedures are associated with an improved outcome than traditional ablation procedures, with a consistently lower recurrence rate.

Identification of a novel presumed cardiac sarcoidosis category for patients at high risk of disease

BACKGROUND

Histologic evidence is required for a definitive diagnosis of cardiac sarcoidosis (CS) by published guidelines; however, the sporadic nature of the disease may produce false negative biopsy results, causing CS to be underdiagnosed. We sought to establish a clinical category of CS absent histologic findings.

METHODS

Patients evaluated for CS were stratified into 3 groups: probable CS and definite CS based on Heart Rhythm Society (HRS) criteria and presumed CS, ie, patients without any histologic evidence of sarcoidosis, but with unexplained high-grade atrioventricular block or ventricular arrhythmia and findings suggestive of CS on either cardiac magnetic resonance imaging or positron emission tomography. The primary end point was hospitalization-free and overall survival at 10 years.

RESULTS

A total of 383 patients were included in the study: 59, definite CS; 223, probable CS; and 101, presumed CS (62, isolated CS and 39, systemic CS). Compared with patients meeting HRS criteria for CS, patients with presumed CS had lower odds of New York Heart Association class III or IV symptoms (odds ratio [OR], 0.44 [95% CI, 0.23-0.83]; P = .01) but greater odds of previous ventricular tachycardia (OR, 2.4 [95% CI, 1.4-4.0]; P = .001) or history of resuscitated sudden cardiac arrest (OR, 2.9 [95% CI, 1.0-8.6]; P = .05). Hospitalization-free and overall survival were similar among groups (P = .51 and P = .71, respectively).

CONCLUSIONS

Clinical categorization of patients with presumed CS identified a high-risk cohort comparable to patients with histologic evidence of disease, although caution should be exercised in reaching this diagnosis without paying due diligence to the differential diagnosis.

Prognostic value of phase analysis on gated single photon emission computed tomography in patients with cardiac sarcoidosis

BACKGROUND

We aimed to determine the correlation between phase analysis, reflecting the heterogeneity of perfusion defects, and the dyssynchrony of the left ventricle wall motion, and adverse cardiac events in cardiac sarcoidosis (CS) patients.

METHODS

Fifty-seven consecutive patients with diagnosed CS (64 [IQR 55-71] years old, 14 males), who underwent 18F-FDG PET/CT and ECG-gated SPECT, were studied. FDG PET was analysed to measure cardiac metabolic volume (CMV), and total lesion glycolysis (TLG). The SPECT findings, such as LVEF, Summed Rest Score (SRS), bandwidth (BW) were evaluated.

RESULTS

The median of BW was 56° (IQR 40-95). BW showed a strong inverse correlation with LVEF (r = - 0.60, P < 0.0001), and positive correlation with SRS (r = 0.82, P < 0.0001). However, there were no significant correlations between BW and CMV or TLG. The Kaplan-Meier curves revealed a significantly higher rate of MACE in the high BW group (BW > 56°) than the low BW group (BW ≤ 56°) (15.1%/years vs. 4.4%/years, P = 0.025). In multivariable analysis, BW was a significant independent predictor of MACE (P = 0.015).

CONCLUSION

Phase analysis on gated SPECT was a significant and independent predictor of MACE in patients with CS.

Cardiac MRI and Myocardial Injury in COVID-19: Diagnosis, Risk Stratification and Prognosis

Myocardial injury is a common complication of the COVID-19 illness and is associated with a worsened prognosis. Systemic hyperinflammation seen in the advanced stage of COVID-19 likely contributes to myocardial injury. Cardiac magnetic resonance imaging (CMR) is the preferred imaging modality for non-invasive evaluation in acute myocarditis, enabling risk stratification and prognostication. Modified scanning protocols in the pandemic setting reduce risk of exposure while providing critical data regarding cardiac tissue inflammation and fibrosis, chamber remodeling, and contractile function. The growing use of CMR in clinical practice to assess myocardial injury will improve understanding of the acute and chronic sequelae of myocardial inflammation from various pathological etiologies.

Loeffler's Endocarditis: An Integrated Multimodality Approach

Loeffler's endocarditis (LE) is the cardiac manifestation of hypereosinophilic syndrome, a rare systemic disease characterized by the sustained production of eosinophils leading to organ damage. Few data, principally by case reports, are available regarding the diagnostic workup in patients with suspected LE. Thus, we have performed a systematic search of the literature dealing with imaging in LE and propose an integrated multimodality imaging approach in the cardiac diagnostics of LE patients. The aim is to provide an updated state-of-the-art review focused on noninvasive and invasive imaging modalities for this rare and underdiagnosed disease. Standard and advanced echocardiography are typically the first cardiac imaging examinations when LE is suspected and they are also used later in follow-up for prognostic stratification and assessing response to treatment. Cardiac magnetic resonance provides a more detailed anatomical and functional evaluation of cardiac chambers, tissue characterization for the presence and extension of myocardial edema and fibrosis, and ventricular thrombi identification. Computed tomography scan and [18F]-fluoro-deoxy-glucose positron emission tomography may be helpful in selected cases to evaluate the cardiac involvement of LE as well as the other noncardiac manifestations of hypereosinophilic syndrome. Endomyocardial biopsy may be considered in patients with high clinical suspicion of LE if noninvasive imaging findings are confusing or not conclusive. The appropriate use of invasive and noninvasive imaging modalities, combining the available techniques with the patients' clinical features, will hopefully lead to early diagnosis, more accurate staging of disease, and timely treatment of LE that may prevent the irreversible myocardial damage of LE and adverse cardiovascular events.

Folate Receptor β-Targeted PET Imaging of Macrophages in Autoimmune Myocarditis

Currently available imaging techniques have limited specificity for the detection of active myocardial inflammation. Aluminum ¹⁸F-labeled 1,4,7-triazacyclononane-N,N',N″-triacetic acid conjugated folate (¹⁸F-FOL) is a PET tracer targeting folate receptor β (FR-β), which is expressed on activated macrophages at sites of inflammation. We evaluated ¹⁸F-FOL PET for the detection of myocardial inflammation in rats with autoimmune myocarditis and studied the expression of FR-β in human cardiac sarcoidosis specimens. Methods: Myocarditis was induced by immunizing rats (n = 18) with porcine cardiac myosin in complete Freund adjuvant. Control rats (n = 6) were injected with Freund adjuvant alone. ¹⁸F-FOL was intravenously injected, followed by imaging with a small-animal PET/CT scanner and autoradiography. Contrast-enhanced high-resolution CT or ¹⁸F-FDG PET images were used for coregistration. Rat tissue sections and myocardial autopsy samples from 6 patients with cardiac sarcoidosis were studied for macrophages and FR-β. Results: The myocardium of 10 of 18 immunized rats showed focal macrophage-rich inflammatory lesions, with FR-β expression occurring mainly in M1-polarized macrophages. PET images showed focal myocardial ¹⁸F-FOL uptake colocalizing with inflammatory lesions (SUV_mean, 2.1 ± 1.1), whereas uptake in the remote myocardium of immunized rats and controls was low (SUV_mean, 0.4 ± 0.2 and 0.4 ± 0.1, respectively; P < 0.01). Ex vivo autoradiography of tissue sections confirmed uptake of ¹⁸F-FOL in myocardial inflammatory lesions. Uptake of ¹⁸F-FOL in inflamed myocardium was efficiently blocked by a nonlabeled FR-β ligand folate glucosamine in vivo. The myocardium of patients with cardiac sarcoidosis showed many FR-β-positive macrophages in inflammatory lesions. Conclusion: In a rat model of autoimmune myocarditis, ¹⁸F-FOL shows specific uptake in inflamed myocardium containing macrophages expressing FR-β, which were also present in human cardiac sarcoid lesions. Imaging of FR-β expression is a potential approach for the detection of active myocardial inflammation.

Myoglobin for Detection of High-Risk Patients with Acute Myocarditis

There is an unmet need for accurate and practical screening to detect myocarditis. We sought to test the hypothesis that the extent of acute myocarditis, measured by late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR), can be estimated based on routine blood markers. A total of 44 patients were diagnosed with acute myocarditis and included in this study. There was strong correlation between myoglobin and LGE (r_s = 0.73 [95% CI 0.51; 0.87], p < 0.001), while correlation was weak between LGE and TnT-hs (r_s = 0.37 [95% CI 0.09; 0.61], p = 0.01). Receiver operating curve (ROC) analysis determined myoglobin ≥ 87 μg/L as cutoff to identify myocarditis (92% sensitivity, 80% specificity). The data were reproduced in an established model of coxsackievirus B3 myocarditis in mice (n = 26). These data suggest that myoglobin is an accurate marker of acute myocarditis. Graphical Abstract Receiver operating curve analysis determined myoglobin ≥ 87 μg/L as cutoff to identify myocarditis and these data were reproduced in an established model of coxsackievirus B3 myocarditis in mice: CMRI, cardiac magnetic resonance imaging; Mb, myoglobin; LGE, late gadolinium enhancement; ROC, receiver operating curve analysis.

Endomyocardial biopsies in the diagnosis of myocardial involvement in systemic lupus erythematosus

BACKGROUND

Endomyocardial biopsy (EMB) is considered the gold standard for diagnosing myocardial involvement in most inflammatory conditions, including systemic lupus erythematosus (SLE). However, EMBs are rarely performed, and most of the myocardial histopathology reports in SLE consist of postmortem data. We therefore sought to describe the histopathologic findings of contemporary EMBs in SLE performed in clinical practice.

METHODS

A retrospective review of histopathology reports from SLE patients who underwent EMB from 1994 to 2017 was performed. A total of 41 SLE patients had cardiac pathology reports. Of these, 11 histopathology reports were EMBs, and the remaining were valvular specimens.

RESULTS

A total of 11 SLE EMBs were reviewed. It was found that 45% of the patients had hypertension, 27% had coronary artery disease, 9% had hyperlipidemia, and 36% had end-stage renal disease. None had diabetes or smoked. The mean left ventricular ejection fraction was 37%. On histopathology, 10 had mild interstitial fibrosis, 9 had myocyte hypertrophy, 3 had organized blood clots, and 3 had a mild infiltration of lymphocytes and macrophages without clear evidence of myocarditis. None had vasculitis, endocarditis, ischemia, amyloid deposition, or lamellar or curvilinear inclusions.

CONCLUSION

EMBs are rarely performed in SLE. In this case series, nonspecific interstitial fibrosis and myocyte hypertrophy were the most common findings, suggesting EMBs have limited value in the diagnosis of cardiac involvement in SLE and rather rule out competing conditions. These data support the need for diagnostic methods with high sensitivity and specificity for SLE heart disease.

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.

Myocarditis Causing Premature Ventricular Contractions: Insights From the MAVERIC Registry

BACKGROUND

Premature ventricular contractions are a common clinical presentation that drives further diagnostic workup. We hypothesize the presence of underlying inflammation is often unrecognized in these patients with a potential for continued disease progression if not diagnosed and treated early in the disease course.

METHODS

This is a single-center, prospective study including 107 patients with frequent symptomatic premature ventricular contractions (>5000/24 h) and no known ischemic heart disease. Patients underwent a combination of laboratory testing, 18F-fluorodeoxyglucose positron emission tomography scan, cardiac magnetic resonance imaging, and biopsy. Patients were diagnosed with myocarditis based on a multidisciplinary approach and treated with immunosuppressive therapy.

RESULTS

The mean age of the cohort was 57±15 years, 41% were males, and left ventricular ejection fraction was 47±11.8%. Positive positron emission tomography scan was seen in 51% (55/107), of which 51% (28/55) had preserved left ventricle function. Based on clinical profile, 18F-fluorodeoxyglucose-positron emission tomography imaging, cardiac magnetic resonance, and histological data 58% patients (32/55) received immunosuppressive therapy alone and 25.4% (14/55) received immunosuppressive therapy and catheter ablation. Optimal response was seen in 67% (31/46) over a mean follow-up of 6±3 months. In patients with left ventricle systolic dysfunction, 37% (10/27) showed an improvement in mean left ventricular ejection fraction of 13±6%.

CONCLUSIONS

Approximately 51% of patients presenting with frequent premature ventricular contractions have underlying myocardial inflammation in this cohort. 18F-fluorodeoxyglucose-positron emission tomography scan can be a useful modality for early diagnosis and treatment with immunosuppressive therapy in selected patients can improve clinical outcomes.

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.

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.

Diagnosis and Therapy of Cardiac Sarcoidosis: A Clinical Perspective

Cardiac sarcoidosis, either as part of a systemic process or in its isolated form, is an important and increasingly recognized disorder. It is associated with high rates of morbidity and mortality, including sudden cardiac death. Early recognition and prompt initiation of treatment is life-saving. A team approach, involving general cardiologists, cardiac electrophysiologists, cardiac imaging specialists and radiologists, is the key to best diagnose and manage this complex disorder. Advanced cardiac imaging with PET and MRI is useful for both diagnosis and managment of therapy. Treatment for this disorder involves immunosuppresant therapy, ICDs, and guideline-directed medical therapy of congestive heart failure.

Personalized medicine in inflammatory cardiomyopathy

Inflammatory cardiomyopathy is the result of persistent myocardial inflammation which can arise from both infectious or noninfectious causes. While most patients with acute myocarditis recover, up to 20% develop inflammatory cardiomyopathy with chronic heart failure. The interaction between host factors and factors of the agent that triggered myocardial inflammation must be considered to fully understand the individual mechanism of disease. Several inflammatory biomarkers, histology, immunohistochemistry, advanced imaging technologies as well as molecular high-throughput sequencing techniques help to identify disease pathways and to establish a comprehensive, individualized treatment approach, which can include anti-inflammatory medication, antiviral drugs and heart failure therapy. This might help to prevent transition from acute inflammation to persistent heart failure and to restore cardiac function.

Cardiac Magnetic Resonance Imaging in Myocarditis Reveals Persistent Disease Activity Despite Normalization of Cardiac Enzymes and Inflammatory Parameters at 3-Month Follow-Up

BACKGROUND

There is a major unmet need to identify high-risk patients in myocarditis. Although decreasing cardiac and inflammatory markers are commonly interpreted as resolving myocarditis, this assumption has not been confirmed as of today. We sought to evaluate whether routine laboratory parameters at diagnosis predict dynamic of late gadolinium enhancement (LGE) as persistent LGE has been shown to be a risk marker in myocarditis.

METHODS AND RESULTS

Myocarditis was diagnosed based on clinical presentation, high-sensitivity troponin T, and cardiac magnetic resonance imaging, after exclusion of obstructive coronary artery disease by angiography. Cardiac magnetic resonance imaging was repeated at 3 months. LGE extent was analyzed with the software GT Volume. Change in LGE >20% was considered significant. Investigated cardiac and inflammatory markers included high-sensitivity troponin T, creatine kinase, myoglobin, N-terminal B-type natriuretic peptide, C-reactive protein, and leukocyte count. Twenty-four patients were enrolled. Absolute levels of cardiac enzymes and inflammatory markers at baseline did not predict change in LGE at 3 months. Cardiac and inflammatory markers had normalized in 21 patients (88%). LGE significantly improved in 16 patients (67%); however, it persisted to a lesser degree in 17 of them (71%) and increased in a small percentage (21%) despite normalization of cardiac enzymes.

CONCLUSIONS

This is the first study reporting that cardiac enzymes and inflammatory parameters do not sufficiently reflect LGE in myocarditis. Although a majority of patients with normalizing laboratory markers experienced improved LGE, in a small percentage LGE worsened. These data suggest that cardiac magnetic resonance imaging might add value to currently existing diagnostic tools for risk assessment in myocarditis.

A cohort study reveals myocarditis to be a rare and life-threatening presentation of large vessel vasculitis

BACKGROUND

The predominant forms of adult large vessel vasculitis (LVV) are giant cell arteritis (GCA) and Takayasu arteritis (TA). Cardiac involvement in LVV is a cause of morbidity and mortality, particularly in TA. Cardiac failure is most commonly secondary to uncontrolled arterial hypertension or myocardial ischaemia. Pulmonary hypertension and aortic valve incompetence following ascending aortic dilatation represent other serious cardiovascular complications. However, cardiac failure as a consequence of myocarditis is rarely reported, principally in single case reports or in autopsy studies.

METHODS

The Imperial College LVV database was, retrospectively, reviewed to identify patients with cardiac involvement at presentation. Patients with evidence for myocarditis were identified. The cardiac presentation, imaging studies and subsequent medical and surgical management were reviewed in detail.

RESULTS

The cohort included 139 patients with TA and 24 with GCA. Sixteen presented with cardiac failure without a history of ischaemic coronary heart disease, 14 (10%) with TA and 2 (8.3%) with GCA. Cardiovascular disease identified at presentation included aortic regurgitation (n = 11), myocarditis (n = 4) and hypertensive cardiomyopathy secondary to renal artery stenosis (n = 1). Those patients with evidence of myocarditis at presentation (2.8%) underwent transthoracic echocardiography and cardiac magnetic resonance imaging (CMR). These non-invasive techniques were sufficient for diagnosis of clinically significant myocarditis. Furthermore, they were subsequently used to monitor response to treatment, with serial improvement in left ventricular ejection fraction (LVEF) observed in all 4 patients (p < 0.05). Prednisolone plus cyclophosphamide (CyC) therapy was associated with significant improvement in heart failure symptoms and LVEF in 3 cases. In one case where CyC was contraindicated, tocilizumab treatment led to marked improvement in cardiac symptoms.

CONCLUSION

Clinically significant myocarditis in LVV remains a rare but serious presentation. Non-invasive imaging techniques offer an alternative to the gold-standard myocardial biopsy. Initial aggressive immunosuppressive therapy is recommended and led to significant improvements in LVEF and cardiac status.

The Quest for New Approaches in Myocarditis and Inflammatory Cardiomyopathy

Myocarditis is a diverse group of heart-specific immune processes classified by clinical and histopathological manifestations. Up to 40% of dilated cardiomyopathy is associated with inflammation or viral infection. Recent experimental studies revealed complex regulatory roles for several microribonucleic acids and T-cell and macrophage subtypes. Although the prevalence of myocarditis remained stable between 1990 and 2013 at about 22 per 100,000 people, overall mortality from cardiomyopathy and myocarditis has decreased since 2005. The diagnostic and prognostic value of cardiac magnetic resonance has increased with new, higher-sensitivity sequences. Positron emission tomography has emerged as a useful tool for diagnosis of cardiac sarcoidosis. The sensitivity of endomyocardial biopsy may be increased, especially in suspected sarcoidosis, by the use of electrogram guidance to target regions of abnormal signal. Investigational treatments on the basis of mechanistic advances are entering clinical trials. Revised management recommendations regarding athletic participation after acute myocarditis have heightened the importance of early diagnosis.