Imaging of Cardiac Sarcoidosis: An Update and Future Aspects

Cardiac sarcoidosis (CS), an increasingly recognized disease of unknown etiology, is associated with significant morbidity and mortality. Given the limited diagnostic yield of traditional endomyocardial biopsy (EMB), there is increasing reliance on multimodality cardiovascular imaging in the diagnosis and management of CS, with EMB being largely supplanted by the use of 18F-fluorodeoxyglucose (FDG-PET) and cardiac magnetic resonance imaging (CMR). This article aims to provide a comprehensive review of imaging modalities currently utilized in the screening, diagnosis, and monitoring of CS, while highlighting the latest developments in each area.

Diagnostic yield of whole-body 18F-FDG PET/CT in patients with suspected cardiac sarcoidosis

BACKGROUND

Whole-body F-18 FDG PET has been included in the 2014 Heart Rhythm Society guidelines for cardiac sarcoidosis evaluation to identify alternate sites of biopsy prior to endomyocardial biopsy. The purpose of this study was to evaluate the diagnostic yield of whole-body F-18 FDG PET/CT.

METHODS

All adult patients with suspected cardiac sarcoidosis undergoing same-day cardiac F-18 FDG PET/CT and whole-body F-18 FDG PET/CT between 10/1/2016 and 6/14/2021 to assess potential biopsy sites were retrospectively identified. Clinical indications, findings, recommendations, and outcomes were assessed.

RESULTS

Eighty-eight patients were included. Extracardiac PET findings suggestive of sarcoidosis were present in 30 patients (34%), 27 of which had thoracic findings (90%). Sarcoidosis was diagnosed in 11% of patients. Only 1% (1/88) was diagnosed by extrathoracic biopsy of a whole-body PET finding. Incidental findings were common (31%), resulting in 11 additional tests or interventions. Recommendations from extrathoracic findings affected treatment in one case: a drainage catheter placement into an unsuspected pelvic abscess.

CONCLUSION

Addition of whole-body F-18 FDG PET/CT to cardiac F-18 FDG PET/CT for the identification of extrathoracic sites of biopsy in patients with suspected cardiac sarcoidosis has marginal diagnostic yield but commonly results in incidental findings that rarely affect patient outcome.

Assessment of Myocardial 18F-FDG Uptake at PET/CT in Asymptomatic SARS-CoV-2-vaccinated and Nonvaccinated Patients

Background Patients who developed myocarditis following SARS-CoV-2 vaccination show abnormalities on cardiac MRI. However, whether myocardial changes occur in asymptomatic individuals following vaccination is not well established. Purpose To assess myocardial 18Fluorine-fluorodeoxyglucose (18F-FDG) uptake on PET/CT in asymptomatic SARS-CoV-2 vaccinated patients compared to nonvaccinated patients. Materials and Methods This retrospective study included patients who underwent 18F-FDG PET/CT for indications unrelated to myocarditis during the period before (11/1/2020 - 2/16/2021) and after (2/17/20121 - 3/31/2022) SARS-CoV-2 vaccines were available. Myocardial and axillary FDG uptake were quantitatively assessed using maximum standardized uptake value (SUVmax). SUVmax values in all patients and in patients stratified by sex (male/female), age (<40, 41-60, >60 years), and time interval between vaccination and PET/CT were compared using Mann-Whitney U test or Kruskal-Wallis test with post ad -hoc Dwass, Steel, Critchlow-Fligner multiple comparison analysis. Results The study included 303 nonvaccinated patients (mean age, 52.9 years ± 14.9 [SD]; 157 females) and 700 vaccinated patients (mean age, 56.8 years ± 13.7 [SD]; 344 females). Vaccinated patients had overall higher myocardial FDG uptake compared to nonvaccinated patients (median SUVmax, 4.8 [IQR: 3.0-8.5] vs median SUVmax, 3.3 [IQR: 2.5-6.2]; P < .0001). Myocardial SUVmax was higher in vaccinated patients regardless of sex (median range, 4.7-4.9 [IQR: 2.9-8.6]) or patient age (median range, 4.7-5.6 [IQR: 2.9-8.6]) compared to corresponding nonvaccinated groups (sex median range, 3.2-3.9 [IQR: 2.4-7.2]; age median range, 3.3-3.3 [IQR: 2.3-6.1]; P range, <.001-.015). Furthermore, increased myocardial FDG uptake was observed in patients imaged 1-30, 31-60, 61-120, and 121-180 days after their second vaccination (median SUVmax range, 4.6-5.1 [IQR: 2.9-8.6]) and increased ipsilateral axillary uptake was observed in patients imaged 1-30, 31-60, 61-120 days after their 2nd vaccination (median SUVmax range, 1.5-2.0 [IQR: 1.2-3.4]) compared to the nonvaccinated patients (P range, <.001-<.001). Conclusion Compared to nonvaccinated patients, asymptomatic patients who received their 2nd vaccination 1-180 days prior to imaging showed increased myocardial FDG uptake on PET/CT. See also the editorial by Bluemke in this issue.

Suspected Isolated Cardiac Sarcoidosis Initially Presenting as Sustained Ventricular Tachycardia

A 65-year-old man was found to have suspected isolated cardiac sarcoidosis on a positron emission tomography (PET) scan to investigate the cause of sustained monomorphic tachycardia. The patient had episodes of palpitations 12 months prior to this admission, but no cause was ever discovered. Cardiac magnetic resonance (CMR) imaging revealed severe hypokinesis of the inferior segments of the left ventricle, which prompted a subsequent 18F-fluorodeoxyglucose (18F-FDG) PET/CT. The findings were consistent with potential isolated cardiac sarcoidosis as a cause of the fibrosis seen in the left ventricle. As such, the patient was commenced on immunosuppressive therapy and remains well to this day after being fitted with an implantable cardioverter defibrillator (ICD). Isolated cardiac sarcoidosis is a rare phenomenon but remains a diagnostic and therapeutic challenge for clinicians. We report a case of how isolated cardiac sarcoidosis can present as a cause of ventricular tachycardia.

Access to cardiac PET/CT by sarcoidosis patients and cost-effectiveness analysis of cardiac PET/MR compared to the standard of care

IMPORTANCE

Cardiac sarcoidosis is associated with a high mortality rate. Given multiple barriers to obtaining cardiac PET imaging, we suspect individuals with access to this imaging modality are not representative of the Sarcoid patient population, which in the United States are predominantly Black females.

OBJECTIVE

To evaluate the demographics of patients with cardiac PET access and the cost-effectiveness of cardiac PET/MR imaging relative to standard of care.

DESIGN

This is a retrospective, observational study. The demographic information of patients with suspected cardiac sarcoidosis and cardiac PET/CT imaging within a national registry of sarcoidosis were reviewed (n = 4561). An individual-level, continuous, time-state transition model was used for the evaluation of long-term cost-effectiveness for the combined cardiac PET/MR compared to standard of care cardiac MR followed by cardiac PET/CT.

RESULTS

Patients who underwent cardiac PET in the national registry had 88.35% higher odds of being male (p < 0.001) and 43.82% higher odds of being White (p = 0.003) than their counterparts who did not have cardiac PET imaging. Combined cardiac PET/MR had overall lower total lifetime costs ($8761 vs $10,777) and overall improved expected quality of life-years compared to the standard of care (0.77 vs 0.69).

CONCLUSION AND RELEVANCE

The findings suggest that patients with access to cardiac PET/CT are not representative of the patient population most likely to have cardiac sarcoidosis in this limited study evaluation. Universal insurance coverage should be considered for Cardiac PET imaging as same day cardiac PET and MR imaging has potential long-term cost and quality of life benefit.

Challenges of cardiac sarcoidosis

Sarcoidosis is a multisystem granulomatosis of unknown origin, which can involve almost any organ. Most frequently the disease involves the lungs and mediastinal lymph nodes, but it can affect the skin, the eyes, nervous system, the heart, kidneys, joints, muscles, calcium metabolism, and probably any other anecdotical organ involvement. Cardiac sarcoidosis is one of the most challenging involvements, as it can lead to cardiac mortality and morbidity, and also because the diagnosis may be difficult. With no specific symptoms, cardiac sarcoidosis may be difficult to suspect in a patient with no previous extra-cardiac sarcoidosis diagnosis. This manuscript reviews the current knowledge of the diagnosis and decision to treat cardiac sarcoidosis, and illustrates the information with a case presentation of a young adult with no risk factors, no previous diagnosis of sarcoidosis, and with cardiac symptoms impairing his quality of life.

Management of Cardiac Sarcoidosis Using Mycophenolate Mofetil as a Steroid-Sparing Agent

BACKGROUND

Cardiac sarcoidosis (CS) is a major cause of morbidity and mortality in patients with systemic sarcoidosis. Steroid-sparing agents are increasingly used, despite a lack of randomized trials or published guidelines to direct treatment.

METHODS AND RESULTS

This retrospective study included 77 patients with CS treated with prednisone monotherapy (n = 32) or a combination with mycophenolate mofetil (n = 45) between 2003 and 2018. Baseline characteristics and clinical outcomes were evaluated. The mean patient age was 53 ± 11 years at CS diagnosis, 66.2% were male, and 35.1% were Black. The total exposure to maximum prednisone dose (initial prednisone dose × days at dose) was lower in the combination therapy group (1440 mg [interquartile range (IQR), 1200-2760 mg] vs 2710 mg [IQR, 1200-5080 mg]; P = .06). On ¹⁸F-fluorodeoxyglucose positron emission tomography scans, both groups demonstrated a significant decrease in the cardiac maximum standardized uptake value after treatment: a median decrease of 3.9 (IQR 2.7-9.0, P = .002) and 2.9 (IQR 0-5.0, P = .001) for prednisone monotherapy and combination therapy, respectively. Most patients experienced improvement or complete resolution in qualitative cardiac ¹⁸F-fluorodeoxyglucose uptake (92.3% and 70.4% for the prednisone and combination therapy groups, respectively). Mycophenolate mofetil was well tolerated.

CONCLUSIONS

Mycophenolate mofetil in combination with prednisone for the treatment of CS may minimize corticosteroid exposure and decrease cardiac inflammation without significant adverse effects.

Sarcoidosis: A Clinical Overview from Symptoms to Diagnosis

Sarcoidosis is a multi-system disease of unknown etiology characterized by the formation of granulomas in various organs. It affects people of all ethnic backgrounds and occurs at any time of life but is more frequent in African Americans and Scandinavians and in adults between 30 and 50 years of age. Sarcoidosis can affect any organ with a frequency varying according to ethnicity, sex and age. Intrathoracic involvement occurs in 90% of patients with symmetrical bilateral hilar adenopathy and/or diffuse lung micronodules, mainly along the lymphatic structures which are the most affected system. Among extrapulmonary manifestations, skin lesions, uveitis, liver or splenic involvement, peripheral and abdominal lymphadenopathy and peripheral arthritis are the most frequent with a prevalence of 25-50%. Finally, cardiac and neurological manifestations which can be the initial manifestation of sarcoidosis, as can be bilateral parotitis, nasosinusal or laryngeal signs, hypercalcemia and renal dysfunction, affect less than 10% of patients. The diagnosis is not standardized but is based on three major criteria: a compatible clinical and/or radiological presentation, the histological evidence of non-necrotizing granulomatous inflammation in one or more tissues and the exclusion of alternative causes of granulomatous disease. Certain clinical features are considered to be highly specific of the disease (e.g., Löfgren's syndrome, lupus pernio, Heerfordt's syndrome) and do not require histological confirmation. New diagnostic guidelines were recently published. Specific clinical criteria have been developed for the diagnosis of cardiac, neurological and ocular sarcoidosis. This article focuses on the clinical presentation and the common differentials that need to be considered when appropriate.

Arrhythmias in Cardiac Sarcoidosis Bench to Bedside: A Case-Based Review

Cardiac sarcoidosis is a component of an often multiorgan granulomatous disease of still uncertain cause. It is being recognized with increasing frequency, mainly as the result of heightened awareness and new diagnostic tests, specifically cardiac magnetic resonance imaging and ¹⁸F-fluorodeoxyglucose positron emission tomography scans. The purpose of this case-based review is to highlight the potentially life-saving importance of making the early diagnosis of cardiac sarcoidosis using these new tools and to provide a framework for the optimal care of patients with this disease. We will review disease mechanisms as currently understood, associated arrhythmias including conduction abnormalities, and atrial and ventricular tachyarrhythmias, guideline-directed diagnostic criteria, screening of patients with extracardiac sarcoidosis, and the use of pacemakers and defibrillators in this setting. Treatment options, including those related to heart failure, and those which may help clarify disease mechanisms are included.

Cardiac sarcoidosis as an incidental finding: A case report

BACKGROUND

This case illustrates the evaluation of a healthy young male with ECG anomalies in a perioperative electrocardiogram (ECG) that ended up with the diagnosis of a severe systemic disease.

CASE

A 28-year-old man was attended at the outpatient cardiology department to perform a preoperative ECG for lacrimal duct obstruction surgery, which showed Q and T negative waves in inferior leads. Echocardiogram and cardiac magnetic resonance (CMR) displayed left ventricular (LV) aneurysm at basal segments of the inferior, posterior, and lateral wall with myocardial thinning and dyskinesia. CMR and thoracic computed tomography (CT) showed bilateral nodular images in parotid glands, cervical, and thoracic lymphadenopathies. All those findings suggested the diagnosis of sarcoidosis, which was supported by Gallium-67 single-photon emission computed tomography (SPECT) results and finally confirmed by skin biopsy.

CONCLUSIONS

The present case highlights the complexity of sarcoidosis diagnosis. This young male was apparently asymptomatic; however, at presentation, he actually had three manifestations of active sarcoidosis: lacrimal duct obstruction, skin lesions, and cervical lymphadenopathies. It is essential to have a low threshold for sarcoidosis suspicion in the setting of unexplained systemic signs and symptoms.

Cardiac sarcoidosis: Case presentation and Review of the literature

Cardiac sarcoidosis usually occurs in the context of systemic disease; however, isolated cardiac involvement can occur in up to 25% of cases and tends to be clinically silent. When symptoms are present, they are often nonspecific and occasionally fatal, representing a diagnostic challenge. A high index of clinical suspicion and the integration of appropriate imaging, laboratory, and pathologic findings is always required. Treatment aims to control the systemic inflammatory condition while preventing further cardiac damage. However, even with adequate diagnosis and treatment strategies, prognosis remains poor. We describe the case of a patient who presented with cardiac symptoms, whose initial examination was unrevealing. Diagnosis was made retrospectively based on later systemic manifestations that revealed characteristic sarcoidosis findings.

PET/CT Evaluation of Cardiac Sarcoidosis

The increasing implementation of advanced cardiovascular imaging in the form of cardiac PET/CT has had a significant impact on the management of cardiac sarcoidosis, which continues to evolve. This review summarizes the role of PET/CT imaging in sarcoidosis with a specific focus on (1) indications, (2) patient preparation, (3) test performance, (4) study interpretation, (5) clinical relevance of findings, (6) comparison to alternative imaging modalities, and finally (7) introduction of areas of anticipated development and research.