Myocardial Involvement in Patients With Histologically Diagnosed Cardiac Sarcoidosis: A Systematic Review and Meta-Analysis of Gross Pathological Images From Autopsy or Cardiac Transplantation Cases

Atrial structural remodeling and atrial fibrillation substrate: A histopathological perspective

Atrial fibrillation (AF) substrate progresses with the advancement of atrial structural remodeling, resulting in AF perpetuation and recurrence. Although fibrosis is considered a hallmark of atrial structural remodeling, the histological background has not been fully elucidated because obtaining atrial specimens is difficult, especially in patients not undergoing open-heart surgery. Bipolar voltage reduction evaluated using electroanatomic mapping during AF ablation is considered a surrogate marker for the progression of structural remodeling; however, histological validation is lacking. We developed an intracardiac echocardiography-guided endomyocardial atrial biopsy technique to evaluate atrial structural remodeling in patients undergoing catheter ablation for nonvalvular AF. The histological factors associated with a decrease in bipolar voltage were interstitial fibrosis, as well as an increase in myocardial intercellular space preceding fibrosis, myofibrillar loss, and a decrease in cardiomyocyte nuclear density, which is a surrogate marker for cardiomyocyte density. Cardiomyocyte hypertrophy is closely associated with a decrease in cardiomyocyte nuclear density, suggesting that hypertrophic changes compensate for cardiomyocyte loss. Electron microscopy also revealed that increased intercellular spaces indicated the leakage of plasma components owing to increased vascular permeability. Additionally, amyloid deposition was observed in 4 % of biopsy cases. Only increased intercellular space and interstitial fibrosis were significantly higher for long-standing persistent AF than for paroxysmal AF and associated with recurrence after AF ablation, suggesting that this interstitial remodeling is the AF substrate. An increase in intercellular space that occurs early in AF formation is a therapeutic target for the AF substrate, which prevents irreversible interstitial degeneration due to collagen accumulation. This endomyocardial atrial biopsy technique will allow the collection of atrial tissue from a wide variety of patients and significantly facilitate the elucidation of the mechanisms of atrial cardiomyopathy, structural remodeling, and AF substrates.

Diagnosis and Management of Cardiac Sarcoidosis: A Scientific Statement From the American Heart Association

Cardiac sarcoidosis is an infiltrative cardiomyopathy that results from granulomatous inflammation of the myocardium and may present with high-grade conduction disease, ventricular arrhythmias, and right or left ventricular dysfunction. Over the past several decades, the prevalence of cardiac sarcoidosis has increased. Definitive histological confirmation is often not possible, so clinicians frequently face uncertainty about the accuracy of diagnosis. Hence, the likelihood of cardiac sarcoidosis should be thought of as a continuum (definite, highly probable, probable, possible, low probability, unlikely) rather than in a binary fashion. Treatment should be initiated in individuals with clinical manifestations and active inflammation in a tiered approach, with corticosteroids as first-line treatment. The lack of randomized clinical trials in cardiac sarcoidosis has led to treatment decisions based on cohort studies and consensus opinions, with substantial variation observed across centers. This scientific statement is intended to guide clinical practice and to facilitate management conformity by providing a framework for the diagnosis and management of cardiac sarcoidosis.

Diagnostic and management strategies in cardiac sarcoidosis

Cardiac sarcoidosis (CS) is increasingly recognized in the context of with otherwise unexplained electrical or structural heart disease due to improved diagnostic tools and awareness. Therefore, clinicians require improved understanding of this rare but fatal disease to care for these patients. The cardinal features of CS, include arrhythmias, atrio-ventricular conduction delay and cardiomyopathy. In addition to treatments tailored to these cardiac manifestations, immunosuppression plays a key role in active CS management. However, clinical trial and consensus guidelines are limited to guide the use of immunosuppression in these patients. This review aims to provide a practical overview to the current diagnostic challenges, treatment approach, and future opportunities in the field of CS.

The Role of Magnetic Resonance Imaging in Cardiomyopathies in the Light of New Guidelines: A Focus on Tissue Mapping

Cardiomyopathies (CMPs) are a group of myocardial disorders that are characterized by structural and functional abnormalities of the heart muscle. These abnormalities occur in the absence of coronary artery disease (CAD), hypertension, valvular disease, and congenital heart disease. CMPs are an increasingly important topic in the field of cardiovascular diseases due to the complexity of their diagnosis and management. In 2023, the ESC guidelines on cardiomyopathies were first published, marking significant progress in the field. The growth of techniques such as cardiac magnetic resonance imaging (CMR) and genetics has been fueled by the development of multimodal imaging approaches. For the diagnosis of CMPs, a multimodal imaging approach, including CMR, is recommended. CMR has become the standard for non-invasive analysis of cardiac morphology and myocardial function. This document provides an overview of the role of CMR in CMPs, with a focus on tissue mapping. CMR enables the characterization of myocardial tissues and the assessment of cardiac functions. CMR sequences and techniques, such as late gadolinium enhancement (LGE) and parametric mapping, provide detailed information on tissue composition, fibrosis, edema, and myocardial perfusion. These techniques offer valuable insights for early diagnosis, prognostic evaluation, and therapeutic guidance of CMPs. The use of quantitative CMR markers enables personalized treatment plans, improving overall patient outcomes. This review aims to serve as a guide for the use of these new tools in clinical practice.

Nonischemic or Dual Cardiomyopathy in Patients With Coronary Artery Disease

BACKGROUND

Randomized trials in obstructive coronary artery disease (CAD) have largely shown no prognostic benefit from coronary revascularization. Although there are several potential reasons for the lack of benefit, an underexplored possible reason is the presence of coincidental nonischemic cardiomyopathy (NICM). We investigated the prevalence and prognostic significance of NICM in patients with CAD (CAD-NICM).

METHODS

We conducted a registry study of consecutive patients with obstructive CAD on coronary angiography who underwent contrast-enhanced cardiovascular magnetic resonance imaging for the assessment of ventricular function and scar at 4 hospitals from 2004 to 2020. We identified the presence and cause of cardiomyopathy using cardiovascular magnetic resonance imaging and coronary angiography data, blinded to clinical outcomes. The primary outcome was a composite of all-cause death or heart failure hospitalization, and secondary outcomes were all-cause death, heart failure hospitalization, and cardiovascular death.

RESULTS

Among 3023 patients (median age, 66 years; 76% men), 18.2% had no cardiomyopathy, 64.8% had ischemic cardiomyopathy (CAD+ICM), 9.3% had CAD+NICM, and 7.7% had dual cardiomyopathy (CAD+dualCM), defined as both ICM and NICM. Thus, 16.9% had CAD+NICM or dualCM. During a median follow-up of 4.8 years (interquartile range, 2.9, 7.6), 1116 patients experienced the primary outcome. In Cox multivariable analysis, CAD+NICM or dualCM was independently associated with a higher risk of the primary outcome compared with CAD+ICM (adjusted hazard ratio, 1.23 [95% CI, 1.06-1.43]; P=0.007) after adjustment for potential confounders. The risks of the secondary outcomes of all-cause death and heart failure hospitalization were also higher with CAD+NICM or dualCM (hazard ratio, 1.21 [95% CI, 1.02-1.43]; P=0.032; and hazard ratio, 1.37 [95% CI, 1.11-1.69]; P=0.003, respectively), whereas the risk of cardiovascular death did not differ from that of CAD+ICM (hazard ratio, 1.15 [95% CI, 0.89-1.48]; P=0.28).

CONCLUSIONS

In patients with CAD referred for clinical cardiovascular magnetic resonance imaging, NICM or dualCM was identified in 1 of every 6 patients and was associated with worse long-term outcomes compared with ICM. In patients with obstructive CAD, coincidental NICM or dualCM may contribute to the lack of prognostic benefit from coronary revascularization.

The inflammatory spectrum of cardiomyopathies

Infiltration of the myocardium with various cell types, cytokines and chemokines plays a crucial role in the pathogenesis of cardiomyopathies including inflammatory cardiomyopathies and myocarditis. A more comprehensive understanding of the precise immune mechanisms involved in acute and chronic myocarditis is essential to develop novel therapeutic approaches. This review offers a comprehensive overview of the current knowledge of the immune landscape in cardiomyopathies based on etiology. It identifies gaps in our knowledge about cardiac inflammation and emphasizes the need for new translational approaches to improve our understanding thus enabling development of novel early detection methods and more effective treatments.

Profibrotic COVID-19 subphenotype exhibits enhanced localized ER-dependent HSP47+ expression in cardiac myofibroblasts in situ

We recently described a subgroup of autopsied COVID-19 subjects (∼40%), termed 'profibrotic phenotype,' who exhibited clusters of myofibroblasts (Mfbs), which were positive for the collagen-specific chaperone heat shock protein 47 (HSP47+) in situ. This report identifies increased, localized (hot spot restricted) expression of αSMA, COLα1, POSTN and FAP supporting the identity of HSP47+ cells as myofibroblasts and characterizing a profibrotic extracellular matrix (ECM) phenotype. Coupled with increased GRP78 in COVID-19 subjects, these data could reflect induction of the unfolded protein response for mitigation of proteostasis (i.e., protein homeostasis) dysfunction in discrete clusters of cells. ECM shifts in selected COVID-19 subjects occur without significant increases in either global trichrome positive staining or myocardial injury based quantitively on standard H&E scoring. Our findings also suggest distinct mechanism(s) for ECM remodeling in the setting of SARS-CoV-2 infection. The ratio of CD163+/CD68+ cells is increased in hot spots of profibrotic hearts compared with either controls or outside of hot spots in COVID-19 subjects. In sum, matrix remodeling of human COVID-19 hearts in situ is characterized by site-restricted profibrotic mediated (e.g., HSP47+ Mfbs, CD163+ Mφs) modifications in ECM (i.e., COLα1, POSTN, FAP), with a strong correlation between COLα1 and HSP47+cells within hot spots. Given the established associations of viral infection (e.g., human immunodeficiency virus; HIV), myocardial fibrosis and sudden cardiac death, early screening tools (e.g., plasma biomarkers, noninvasive cardiac magnetic resonance imaging) for diagnosis, monitoring and treatment of fibrotic ECM remodeling are warranted for COVID-19 high-risk populations.

Update on cardiac sarcoidosis

Cardiac sarcoidosis is an inflammatory myocardial disease of unknown etiology. It is characterized by the deposition of non-caseating granulomas that may involve any part of the heart. Cardiac sarcoidosis is often under-diagnosed or recognized partly due to the heterogeneous clinical presentation of the disease. The three most frequent clinical manifestations of cardiac sarcoidosis are atrioventricular block, ventricular arrhythmias, and heart failure. A definitive diagnosis of cardiac sarcoidosis can be made with histology findings from an endomyocardial biopsy. However, the diagnosis in the majority of cases is based on findings from the clinical presentation and advanced imaging due to the low sensitivity of endomyocardial biopsy. The Heart Rhythm Society (HRS) 2014 expert consensus statement and the Japanese Ministry of Health and Welfare criteria are the two most commonly used diagnostic criteria sets. This review article summarizes the available evidence on cardiac sarcoidosis, focusing on the diagnostic criteria and stepwise approach to its management.

Phenotyping heart failure by cardiac magnetic resonance imaging of cardiac macro- and microscopic structure: state of the art review

Heart failure demographics have evolved in past decades with the development of improved diagnostics, therapies, and prevention. Cardiac magnetic resonance (CMR) has developed in a similar timeframe to become the gold-standard non-invasive imaging modality for characterizing diseases causing heart failure. CMR techniques to assess cardiac morphology and function have progressed since their first use in the 1980s. Increasingly efficient acquisition protocols generate high spatial and temporal resolution images in less time. This has enabled new methods of characterizing cardiac systolic and diastolic function such as strain analysis, exercise real-time cine imaging and four-dimensional flow. A key strength of CMR is its ability to non-invasively interrogate the myocardial tissue composition. Gadolinium contrast agents revolutionized non-invasive cardiac imaging with the late gadolinium enhancement technique. Further advances enabled quantitative parametric mapping to increase sensitivity at detecting diffuse pathology. Novel methods such as diffusion tensor imaging and artificial intelligence-enhanced image generation are on the horizon. Magnetic resonance spectroscopy (MRS) provides a window into the molecular environment of the myocardium. Phosphorus (31P) spectroscopy can inform the status of cardiac energetics in health and disease. Proton (1H) spectroscopy complements this by measuring creatine and intramyocardial lipids. Hyperpolarized carbon (13C) spectroscopy is a novel method that could further our understanding of dynamic cardiac metabolism. CMR of other organs such as the lungs may add further depth into phenotypes of heart failure. The vast capabilities of CMR should be deployed and interpreted in context of current heart failure challenges.

Management of the arrhythmic manifestations of cardiac sarcoidosis

Cardiac sarcoidosis (CS) is characterised by a high burden of arrhythmic manifestations and cardiac electrophysiologists play an important role in both the diagnosis and management of this challenging condition. CS is characterised by the formation of noncaseating granulomas within the myocardium, which can subsequently lead to fibrosis. Clinical presentations of CS are varied and depend on the location and extent of granulomas. Patients may present with atrioventricular block, ventricular arrhythmias, sudden cardiac death or heart failure. CS is being increasing diagnosed through use of advanced cardiac imaging, however endomyocardial biopsy is often still required to confirm the diagnosis. Due to the low sensitivity of fluoroscopy-guided right ventricular biopsies, three-dimensional electro-anatomical mapping and electrogram-guided biopsies are being investigated as a means to improve diagnostic yield. Cardiac implantable electronic devices are often required in the management of CS, either for pacing or for primary or secondary prevention of ventricular arrhythmias. Catheter ablation for ventricular arrythmias may also be required, although this is often associated with high recurrence rates due to the challenging nature of the arrhythmogenic substrate. This review will explore the underlying mechanisms of the arrhythmic manifestations of CS, provide an overview of current clinical practice guidelines, and examine the important role that cardiac electrophysiologists play in managing patients with CS.

Prognostic value of late-gadolinium enhancement on cardiac magnetic resonance in patients with cardiac sarcoidosis

BACKGROUND

Late-gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) is a predictor of adverse events in patients with cardiac sarcoidosis (CS), but available studies had small sample sizes and did not consider all relevant endpoints.

OBJECTIVE

To evaluate the association between LGE on CMR in patients with CS and mortality, ventricular arrhythmias (VA) and sudden cardiac death (SCD), and heart failure (HF) hospitalization.

METHODS

A literature search was conducted for studies reporting the association between LGE in CS and the study endpoints. The endpoints were mortality, VA and SCD, and HF hospitalization. The search included the following databases: Ovid MEDLINE, EMBASE, Web of Science, and Google Scholar. The search was not restricted to time or publication status. The minimum follow-up duration was 1 year.

RESULTS

A total of 17 studies and 1915 CS patients (595 with LGE vs. 1320 without LGE) were included; mean follow-up was 3.3 years (ranging between 17 and 84 months). LGE was associated with increased all-cause mortality (OR 6.05, 95% CI 3.16-11.58; p < .01), cardiovascular mortality (OR 5.83, 95% CI 2.89-11.77; p < .01), and VA and SCD (OR 16.48, 95% CI 8.29-32.73; p < .01). Biventricular LGE was associated with increased VA and SCD (OR 6.11, 95% CI 1.14-32.68; p = .035). LGE was associated with an increased HF hospitalization (OR 17.47, 95% CI 5.54-55.03; p < .01). Heterogeneity was low: df = 7 (p = .43), I2 = 0%.

CONCLUSIONS

LGE in CS patients is associated with increased mortality, VA and SCD, and HF hospitalization. Biventricular LGE is associated with an increased risk of VA and SCD.

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.

Clinical features and prognosis of isolated cardiac sarcoidosis diagnosed using new guidelines with dedicated FDG PET/CT

BACKGROUND

Diagnostic guidelines for isolated cardiac sarcoidosis (iCS) were first proposed in 2016, but there are few reports on the imaging and prognosis of iCS. This study aimed to evaluate the use of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) imaging in predicting iCS prognosis.

METHODS AND RESULTS

We retrospectively reviewed the clinical and imaging data of 306 consecutive patients with suspected CS who underwent FDG PET/CT with a dedicated preparation protocol and included 82 patients (55 with systemic sarcoidosis including cardiac involvement [sCS], 27 with iCS) in the study. We compared the FDG PET/CT findings between the two groups. We examined the relationship between the CS type and the rate of adverse cardiac events. The iCS group had a significantly lower target-to-background ratio than the sCS group (P = 0.0010). The event-free survival rate was significantly lower in the iCS group than the sCS group (log-rank test, P < 0.0001). iCS was identified as an independent prognostic factor for adverse events (hazard ratio 3.82, P = 0.0059).

CONCLUSION

iCS was an independent prognostic factor for adverse cardiac events in patients with CS. The clinical diagnosis of iCS based on FDG PET/CT and new guidelines may be important.

Cardiovascular Magnetic Resonance Imaging Phenotypes and Long-term Outcomes in Patients With Suspected Cardiac Sarcoidosis

Importance

In patients with sarcoidosis with suspected cardiac involvement, late gadolinium enhancement (LGE) on cardiovascular magnetic resonance imaging (CMR) identifies those with an increased risk of adverse outcomes. However, these outcomes are experienced by only a minority of patients with LGE, and identifying this subgroup may improve treatment and outcomes in these patients.

Objective

To assess whether CMR phenotypes based on left ventricular ejection fraction (LVEF) and LGE in patients with suspected cardiac sarcoidosis (CS) are associated with adverse outcomes during follow-up.

Design, Setting, and Participants

This cohort study included consecutive patients with histologically proven sarcoidosis who underwent CMR for the evaluation of suspected CS from 2004 to 2020 with a median follow-up of 4.3 years at an academic medical center in Minnesota. Demographic data, medical history, comorbidities, medications, and outcome data were collected blinded to CMR data.

Exposures

CMR phenotypes were identified based on LVEF and LGE presence and features. LGE was classified as pathology-frequent or pathology-rare based on the frequency of cardiac damage features on gross pathology assessment of the hearts of patients with CS who had sudden cardiac death or cardiac transplant.

Main Outcomes and Measures

Composite of ventricular arrhythmic events and composite of heart failure events.

Results

Among 504 patients (mean [SD] age, 54.1 [12.5] years; 242 [48.0%] female and 262 [52.0%] male; 2 [0.4%] American Indian or Alaska Native, 6 [1.2%] Asian, 90 [17.9%] Black or African American, 399 [79.2%] White, 5 [1.0%] of 2 or more races (including the above-mentioned categories and Native Hawaiian or Other Pacific Islander), and 2 [0.4%] of unknown race; 4 [0.8%] Hispanic or Latino, 498 [98.8%] not Hispanic or Latino, and 2 [0.4%] of unknown ethnicity), 4 distinct CMR phenotypes were identified: normal LVEF and no LGE (n = 290; 57.5%), abnormal LVEF and no LGE (n = 53; 10.5%), pathology-frequent LGE (n = 103; 20.4%), and pathology-rare LGE (n = 58; 11.5%). The phenotype with pathology-frequent LGE was associated with a high risk of arrhythmic events (hazard ratio [HR], 12.12; 95% CI, 3.62-40.57; P < .001) independent of LVEF and extent of left ventricular late gadolinium enhancement (LVLGE). It was also associated with a high risk of heart failure events (HR, 2.49; 95% CI, 1.19-5.22; P = .02) independent of age, pulmonary hypertension, LVEF, right ventricular ejection fraction, and LVLGE extent. Risk of arrhythmic events was greater with an increasing number of pathology-frequent LGE features. The absence of the pathology-frequent LGE phenotype was associated with a low risk of arrhythmic events, even in the presence of LGE or abnormal LVEF.

Conclusions and Relevance

This cohort study found that a CMR phenotype involving pathology-frequent LGE features was associated with a high risk of arrhythmic and heart failure events in patients with sarcoidosis. The findings indicate that CMR phenotypes could be used to optimize clinical decision-making for treatment options, such as implantable cardioverter-defibrillators.

Role of Cardiovascular Magnetic Resonance to Assess Cardiovascular Inflammation

Cardiovascular inflammatory diseases still represent a challenge for physicians. Inflammatory cardiomyopathy, pericarditis, and large vessels vasculitis can clinically mimic a wide spectrum of diseases. While the underlying etiologies are varied, the common physio-pathological process is characterized by vasodilation, exudation, leukocytes infiltration, cell damage, and fibrosis. Cardiovascular magnetic resonance (CMR) allows the visualization of some of these diagnostic targets. CMR provides not only morphological and functional assessment but also tissue catheterization revealing edema, hyperemia, tissue injury, and reparative fibrosis through T2 weighted images, early and late gadolinium enhancement, and parametric mapping techniques. Recent developments showed the role of CMR in the identification of ongoing inflammation also in other CV diseases like myocardial infarction, atherosclerosis, arrhythmogenic and hypertrophic cardiomyopathy. Future developments of CMR, aiming at the specific assessment of immune cell infiltration, will give deeper insight into cardiovascular inflammatory diseases.

Meta-Analysis of Catheter Ablation Outcomes in Patients With Cardiac Sarcoidosis Refractory Ventricular Tachycardia

Cardiac sarcoidosis (CS) frequently leads to ventricular tachycardia (VT), which is often refractory to antiarrhythmic and/or immunosuppressive medications and requires catheter ablation. We conducted a systematic review and meta-analysis to evaluate the role of catheter ablation in patients with refractory VT undergoing catheter ablation. We searched PubMed, Embase, and Scopus databases from their inception to December 31, 2021 with search terms "cardiac sarcoidosis" AND "electrophysiological studies OR ablation." Fifteen studies were ultimately included for evaluation. Patient demographics, VT mapping, and acute and long-term procedural outcomes were extracted. A total of 15 studies were included in our meta-analysis, with a total of 401 patients, of whom 66% were male, with ages ranging from 39 to 64 years. A total of 95% of patients were on antiarrhythmics and 79% of patients were on immunosuppressants. Left ventricular ejection fraction ranged from 35% to 49% and procedure duration ranged from 269 to 462 minutes. Ablation was reported using both irrigated and nonirrigated catheter tips. A total of 25% of patients (84/339) underwent repeat ablation. Acute procedural success was achieved in 57% (161/285). Procedure complications occurred in 5.7% (17/297) procedures. VT recurrence after first ablation was 55% (confidence interval 48% to 63%, 213/401); VT recurrence after multiple ablations was 37% (81/220). The composite end point of death, heart transplant, and left ventricular assist device implantation was 21% (confidence interval 14% to 30%, 55/297). In conclusion, catheter ablation is a useful modality in patients with CS with refractory VT. However, patients with CS presenting with refractory VT after undergoing VT ablation carry a poor prognosis.

The role of cardiovascular magnetic resonance in the evaluation of acute myocarditis and inflammatory cardiomyopathies in clinical practice - a comprehensive review

Inflammatory cardiomyopathy (I-CMP) is defined as myocarditis in association with cardiac dysfunction and/or ventricular remodelling. It is characterized by inflammatory cell infiltration into the myocardium and has heterogeneous infectious and non-infectious aetiologies. A complex interplay of genetic, autoimmune, and environmental factors contributes to the substantial risk of deteriorating cardiac function, acute heart failure, and arrhythmia as well as chronic dilated cardiomyopathy and its sequelae. Multi-parametric cardiovascular magnetic resonance (CMR) imaging is sensitive to many tissue changes that occur during myocardial inflammation, regardless of its aetiology. In this review, we summarize the various aetiologies of I-CMP and illustrate how CMR contributes to non-invasive diagnosis.

Basal interventricular septum thinning and long-term left ventricular function in patients with sarcoidosis

BACKGROUND

Basal interventricular septum (IVS) thinning on transthoracic echocardiography (TTE) is highly specific to cardiac sarcoidosis. Although basal IVS thinning is listed as one of the five major diagnostic criteria for cardiac sarcoidosis, its association with long-term cardiac function has not been investigated. This study aimed to evaluate the epidemiology and clinical relevance of basal IVS thinning in a clinic-based cohort of patients with sarcoidosis.

METHODS

This retrospective observational study was conducted at a general sarcoidosis clinic. The incidence of basal IVS thinning and associations with variables at baseline and a delayed onset of left ventricular (LV) dysfunction (LV ejection fraction [LVEF] < 50%) were analyzed.

RESULTS

Of the 1009 patients, 23 (2.3%) had basal IVS thinning. Basal IVS thinning was associated with cardiac pacemaker (PM) implantation at baseline (adjusted odds ratio = 20.5; 95% confidence interval [CI] = 7.9-53.2; P < 0.01). Of the 768 patients with an LVEF of ≥50% at baseline who underwent one or more longitudinal TTEs after baseline, 36 (4.7%) developed LV dysfunction over a median observation period of 88.9 months. Basal IVS thinning and PM implantation at baseline were the independent predictors of a delayed onset of LV dysfunction (basal IVS thinning, adjusted hazard ratio [HR] = 3.7; 95% CI = 1.5-9.6; PM implantation, adjusted HR = 15.7; 95% CI = 7.4-33.3).

CONCLUSIONS

Basal IVS thinning in patients with sarcoidosis can predict a delayed onset of LV dysfunction even when the LV function is preserved at the time of detection.

Histology of Cardiac Sarcoidosis with Novel Considerations Arranged upon a Pathologic Basis

Sarcoidosis is a rare disease of isolated or diffuse granulomatous inflammation. Although any organs can be affected by sarcoidosis, cardiac sarcoidosis is a fatal disorder, and it is crucial to accurately diagnose it to prevent sudden death due to dysrhythmia. Although endomyocardial biopsy is invasive and has limited sensitivity for identifying granulomas, it is the only modality that yields a definitive diagnosis of cardiac sarcoidosis. It is imperative to develop novel pathological approaches for the precise diagnosis of cardiac sarcoidosis. Here, we aimed to discuss commonly used diagnostic criteria for cardiac sarcoidosis and to summarize useful and novel histopathologic criteria of cardiac sarcoidosis. While classical histologic observations including noncaseating granulomas and multinucleated giant cells (typically Langhans type) are the most important findings, others such as microgranulomas, CD68⁺ CD163^- pro-inflammatory (M1) macrophage accumulation, CD4/CD8 T-cell ratio, Cutibacterium acnes components, lymphangiogenesis, confluent fibrosis, and fatty infiltration may help to improve the sensitivity of endomyocardial biopsy for detecting cardiac sarcoidosis. These novel histologic findings are based on the pathology of cardiac sarcoidosis. We also discussed the principal histologic differential diagnoses of cardiac sarcoidosis, such as tuberculosis myocarditis, fungal myocarditis, giant cell myocarditis, and dilated cardiomyopathy.

Advances in Diagnostic Imaging for Cardiac Sarcoidosis

Sarcoidosis is a systemic granulomatous disease of unknown etiology, and its clinical presentation depends on the affected organ. Cardiac sarcoidosis (CS) is one of the leading causes of death among patients with sarcoidosis. The clinical manifestations of CS are heterogeneous, and range from asymptomatic to life-threatening arrhythmias and progressive heart failure due to the extent and location of granulomatous inflammation in the myocardium. Advances in imaging techniques have played a pivotal role in the evaluation of CS because histological diagnoses obtained by myocardial biopsy tend to have lower sensitivity. The diagnosis of CS is challenging, and several approaches, notably those using positron emission tomography and cardiac magnetic resonance imaging (MRI), have been reported. Delayed-enhanced computed tomography (CT) may also be used for diagnosing CS in patients with MRI-incompatible devices and allows acceptable evaluation of myocardial hyperenhancement in such patients. This article reviews the advances in imaging techniques for the evaluation of CS.

Cardiac sarcoidosis: from diagnosis to treatment

Sarcoidosis is a systemic granulomatous disease of unknown cause. Its clinical presentations are heterogeneous and virtually any organ system can be affected, most commonly lungs. The manifestations of cardiac sarcoidosis (CS) are heterogenous depending on the extent and location of the disease and range from asymptomatic forms to life-threatening arrhythmias as well as to progressive heart failure. Cardiac involvement is associated with a worse prognosis. The diagnosis of CS is often challenging and requires a multimodality approach based on current international recommendations. Pharmacological treatment of CS is based on administration of anti-inflammatory therapy (mainly corticosteroids), which is often combined with heart failure medication and/or antiarrhythmics. Nonpharmacological therapeutic approaches in CS cover pacemaker or defibrillator implantation, catheter ablations and heart transplantation. This review aims to summarize the current understanding of CS including its epidemiology, etiopathogenesis, clinical presentations, diagnostic approaches, and therapeutic possibilities.

Sex Differences in Patients With Suspected Cardiac Sarcoidosis Assessed by Cardiovascular Magnetic Resonance Imaging

[Figure: see text].

Clinical Presentation and Treatment of High-Risk Sarcoidosis

Sarcoidosis is a multisystem disease of unknown cause with heterogenous clinical manifestations and variable course. Spontaneous remissions occur in some patients while others have progressive disease impacting survival, organ function, and quality of life. Four high-risk sarcoidosis phenotypes associated with chronic inflammation have recently been identified as high-priority areas for research. These include treatment-refractory pulmonary disease, cardiac sarcoidosis, neurosarcoidosis and multiorgan sarcoidosis. Significant gaps currently exist in understanding of these high-risk manifestations of sarcoidosis, including their natural history, diagnostic criteria, biomarkers, and the treatment strategy such as the ideal agent, optimal dose and treatment duration. The use of registries with well-phenotyped patients is a critical first step to study high-risk sarcoidosis manifestations systematically. We review the diagnostic and treatment approach to high-risk sarcoidosis manifestations. Appropriately identifying these disease sub-groups will help enroll well-phenotyped patients in sarcoidosis registries and clinical trials, a necessary step to narrow existing gaps in understanding of this enigmatic disease.

The Role of Multimodality Imaging in Cardiac Sarcoidosis

The etiology and the progression of sarcoidosis remain unknown. However, cardiac sarcoidosis (CS) is significantly associated with a poor prognosis due to the associated congestive heart failure, arrhythmias (such as an advanced atrioventricular block), and ventricular tachyarrhythmia. Novel imaging modalities are now available to detect CS lesions secondary to active inflammation, granuloma formation, and fibrotic changes. ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and cardiac magnetic resonance imaging (CMR) play essential roles in diagnosing and monitoring patients with confirmed or suspected CS. The following focused review will highlight the emerging role of non-invasive cardiac imaging techniques, including FDG PET/CT and CMR.

Value of 3D mapping-guided endomyocardial biopsy in cardiac sarcoidosis: Case series and narrative review on the value of electro-anatomic mapping-guided endomyocardial biopsies

AIM

Integration of endomyocardial biopsy (EMB) in the diagnostic workup of cardiac sarcoidosis (CS) is under-recognized in current clinical practice, since capturing focal granulomas is challenging. Our aim was to describe our experience with electro-anatomic mapping (EAM)-guided EMB and provide a comprehensive review of the literature.

METHODS AND RESULTS

Five patients (age 49.4 ± 11.4) with suspected CS underwent EAM-guided EMB in Isala Heart Center (Zwolle, the Netherlands) between 2017 and 2019. In all patients, a 3D bipolar voltage map (<0.5-1.5 mV) and unipolar voltage map (LV < 8.3 mV, RV < 5.5 mV) was created using a high-density mapping catheter. The bioptome was connected to the mapping system to guide targeted EMB. Biopsy samples (2-9 samples) were taken from both LV and RV sites, guided by EAM and areas with abnormal electrograms, without complications. CS diagnosis was based on EMB in 2/5 patients. A granuloma was captured in one patient at the LV basal septum with normal bipolar and abnormal unipolar voltage. All patients with delayed enhancement on cardiac magnetic resonance, revealed fibrosis in the biopsy sample. In one patient with suspected isolated cardiac sarcoidosis, diagnosis could not be confirmed by histopathology analysis, while unipolar voltage mapping was abnormal and diastolic potentials were present. Literature search revealed 7 reports (18 patients) describing EAM-guided EMB in CS patients, with 100% of the EMB taken form the RV.

CONCLUSION

Unipolar voltage mapping may be superior to target active inflamed tissue and should be evaluated in future research regarding EAM-guided EMB in CS.

Cardiovascular Magnetic Resonance Imaging and Heart Failure

Purpose of Review

The purpose of this review is to summarize the application of cardiac magnetic resonance (CMR) in the diagnostic and prognostic evaluation of patients with heart failure (HF).

Recent Findings

CMR is an important non-invasive imaging modality in the assessment of ventricular volumes and function and in the analysis of myocardial tissue characteristics. The information derived from CMR provides a comprehensive evaluation of HF. Its unique ability of tissue characterization not only helps to reveal the underlying etiologies of HF but also offers incremental prognostic information.

Summary

CMR is a useful non-invasive tool for the diagnosis and assessment of prognosis in patients suffering from heart failure.

Texture analysis of delayed contrast-enhanced computed tomography to diagnose cardiac sarcoidosis

PURPOSE

To investigate the diagnostic value of texture analysis to differentiate cardiac sarcoidosis (CS) from other non-ischemic cardiomyopathies (non-CS).

MATERIALS AND METHODS

Twenty CS patients and 15 non-CS patients who had undergone myocardial CT delayed enhancement (CTDE) were included. A total of 36 texture features were calculated according to the CT attenuation of CTDE. We investigated the diagnostic value to differentiate CS from non-CS. We also assessed the intra- and inter-rater reproducibility for each feature and inter-observer agreement for visual assessment.

RESULTS

Seven extracted features had significantly higher run length non-uniformity (RLNU) values (5.4 × 10² ± 6.2 × 10² vs. 11.2 × 10² ± 4.9 × 10², p = 0.037) and significantly lower low gray-level zone emphasis (LGZE) values (7.1 × 10^-3 ± 8.6 × 10^-3 vs. 18.1 × 10^-3 ± 16.9 × 10^-3, p = 0.017) in CS than in non-CS. Intra- and inter-rater reproducibility of RLNU and LGZE were excellent (ICCs > 0.8), while inter-observer agreement of visual assessment was poor (kappa = 0.19). The accuracies of texture analysis were 69% with RLNU and 71% with LGZE, which were better than that of visual assessment.

CONCLUSION

Texture analysis of CTDE could differentiate CS from non-CS with high reproducibility.

The role of cardiac magnetic resonance in diagnosis of cardiac sarcoidosis

Sarcoidosis is a systemic granulomatous disease with a high prevalence of cardiac involvement in autopsic studies. Cardiac sarcoidosis is associated with increased cardiovascular morbidity and mortality. Endomyocardial biopsy is a specific technique, but unfortunately not sensitive enough. Non-invasive cardiac imaging has an important role in the evaluation of patients with suspected or confirmed cardiac sarcoidosis. Echocardiography remains the first choice imaging technique because of its availability and low cost. However, this method could not provide tissue characterization or evaluation of disease activity level. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has essential role in diagnosis and monitoring of patients with suspected or confirmed cardiac sarcoidosis. Nevertheless, more recently it has been shown that cardiac magnetic resonance (CMR) might provide useful information about cardiac sarcoidosis. Hybrid imaging approach that includes PET-CMR and PET-CT is particularly interesting for diagnosis, assessment of activity and follow-up in these patients. Diagnostic algorithm in sarcoidosis patients should include clinical data, hybrid imaging and biopsy. Use of different CMR sequences such as cine imaging, late gadolinium enhancement, T1 and T2 mapping, as well as strain imaging, may significantly contribute to diagnosis and monitoring of patients with cardiac sarcoidosis. However, validation of these techniques and particularly T1 and T2 mapping in sarcoidosis patients in large studies is necessary. This review aimed to summarize current knowledge about clinical usefulness of CMR in patients with cardiac sarcoidosis.

Myocardial Involvement in Patients With Histologically Diagnosed Cardiac Sarcoidosis: A Systematic Review and Meta-Analysis of Gross Pathological Images From Autopsy or Cardiac Transplantation Cases

Background

In patients with suspected cardiac sarcoidosis, late gadolinium enhancement on cardiovascular magnetic resonance imaging and/or ¹⁸F‐fluorodeoxyglucose uptake on positron emission tomography are often used to reach a clinical diagnosis of cardiac sarcoidosis. On the basis of data from the imaging literature of clinical cardiac sarcoidosis, no specific features of myocardial involvement are regarded as pathognomonic for cardiac sarcoidosis. Thus, a diagnosis of cardiac sarcoidosis is challenging to make. There has been no systematic analysis of histologically diagnosed cardiac sarcoidosis for patterns of myocardial involvement. We hypothesized that certain patterns of myocardial involvement are more frequent in histologically diagnosed cardiac sarcoidosis.

Methods and Results

We performed a systematic review and meta‐analysis of gross pathological images from the published literature of patients with histologically diagnosed cardiac sarcoidosis who underwent autopsy or cardiac transplantation. Thirty‐three eligible articles provided images of 49 unique hearts. Analysis of these hearts revealed certain features of myocardial involvement in >90% of cases: left ventricular (LV) subepicardial, LV multifocal, septal, and right ventricular free wall involvement. In contrast, other patterns were seen in 0% to 6% of cases: absence of gross LV myocardial involvement, isolated LV midmyocardial involvement, isolated LV subendocardial involvement, isolated LV transmural involvement, absence of septal involvement, or isolated involvement of only one LV level.

Conclusions

In this systematic review and meta‐analysis of histologically diagnosed cardiac sarcoidosis, we identified certain features of myocardial involvement that occurred frequently and others that occurred rarely or never. These patterns could aid the interpretation of cardiovascular magnetic resonance imaging and positron emission tomography imaging and improve the diagnosis and the prognostication of patients with suspected cardiac sarcoidosis.

See Editorial Patel et al

Clinical characteristics and organ system involvement in sarcoidosis: comparison of the University of Minnesota Cohort with other cohorts

BACKGROUND

Sarcoidosis is a systemic granulomatous disease of unknown etiology. Clinical cohort studies of different populations are important to understand the high variability in clinical presentation and disease course of sarcoidosis. The aim of the study is to evaluate clinical characteristics, including organ involvement, pulmonary function tests, and laboratory parameters, in a sarcoidosis cohort at the University of Minnesota. We compare the organ system involvement of this cohort with other available cohorts.

METHODS

We conducted a retrospective data collection and analysis of 187 subjects with biopsy-proven sarcoidosis seen at a tertiary center. Organ system involvement was determined using the WASOG sarcoidosis organ assessment instrument. Clinical phenotype groups were classified using the Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis criteria.

RESULTS

Mean subject age at diagnosis was 45.8 ± 12.4, with a higher proportion of males (55.1%), and a higher proportion of blacks (17.1%) compared to the racial distribution of Minnesota residents (5.95%). The majority (71.1%) of subjects required anti-inflammatory therapy for at least 1 month. Compared to the A Case Control Etiologic Study of Sarcoidosis cohort, there was a higher frequency of extra-thoracic lymph node (34.2% vs. 15.2%), eye (20.9% vs. 11.8%), liver (17.6% vs. 11.5%), spleen (20.9% vs. 6.7%), musculoskeletal (9.6% vs. 0.5%), and cardiac (10.7% vs. 2.3%) involvement in our cohort. A multisystem disease with at least five different organs involved was identified in 13.4% of subjects. A restrictive physiological pattern was observed in 21.6% of subjects, followed by an obstructive pattern in 17.3% and mixed obstructive and restrictive pattern in 2.2%. Almost half (49.2%) were Scadding stages II/III. Commonly employed disease activity markers, including soluble interleukin-2 receptor and angiotensin-converting enzyme, did not differ between treated and untreated groups.

CONCLUSIONS

This cohort features a relatively high frequency of high-risk sarcoidosis phenotypes including cardiac and multiorgan disease. Commonly-utilized serum biomarkers do not identify subpopulations that require or do better with treatment. Findings from this study further highlight the high-variability nature of sarcoidosis and the need for a more reliable biomarker to predict and measure disease severity and outcomes for better clinical management of sarcoidosis patients.

Cardiac Sarcoidosis: A Picture May Be Worth a Thousand Words, But Do We Need More?

See Article Okasha et al

Progressive Thinning of the Basal Interventricular Septum by Giant Cell Myocarditis

We describe a patient with ventricular tachycardia and complete atrioventricular block. Remarkable thinning of the basal interventricular septum preceded left ventricular dysfunction. Endomyocardial biopsy demonstrated giant cell myocarditis. The patient received combined immunosuppressive therapy and a cardioverter-defibrillator. Eligibility screening for heart transplantation was initiated. (Level of Difficulty: Advanced.)

Assessment of the 2017 AHA/ACC/HRS Guideline Recommendations for Implantable Cardioverter-Defibrillator Implantation in Cardiac Sarcoidosis

BACKGROUND

Implantable cardioverter-defibrillators are used to prevent sudden cardiac death in patients with cardiac sarcoidosis. The most recent recommendations for implantable cardioverter-defibrillator implantation in these patients are in the 2017 American Heart Association/American College of Cardiology/Heart Rhythm Society Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death. These recommendations, based on observational studies or expert opinion, have not been assessed. We aimed to assess them.

METHODS

We performed a large retrospective cohort study of patients with biopsy-proven sarcoidosis and known or suspected cardiac sarcoidosis that underwent cardiovascular magnetic resonance imaging. Patients were followed for a composite end point of significant ventricular arrhythmia or sudden cardiac death. The discriminatory performance of the Guideline recommendations was tested using time-dependent receiver operating characteristic analyses. The optimal cutoff for the extent of late gadolinium enhancement predictive of the composite end point was determined using the Youden index.

RESULTS

In 290 patients, the class I and IIa recommendations identified all patients who experienced the composite end point during a median follow-up of 3.0 years. Patients meeting class I recommendations had a significantly higher incidence of the composite end point than those meeting class IIa recommendations. Left ventricular ejection fraction (LVEF) >35% with >5.7% late gadolinium enhancement on cardiovascular magnetic resonance imaging was as sensitive as and significantly more specific than LVEF >35% with any late gadolinium enhancement. Patients meeting 2 class IIa recommendations, LVEF >35% with the need for a permanent pacemaker and LVEF >35% with late gadolinium enhancement >5.7%, had high annualized event rates. Excluding 2 class IIa recommendations, LVEF >35% with syncope and LVEF >35% with inducible ventricular arrhythmia, resulted in improved discrimination for the composite end point.

CONCLUSIONS

We assessed the Guideline recommendations for implantable cardioverter-defibrillator implantation in patients with known or suspected cardiac sarcoidosis and identified topics for future research.