The following are 10 points to remember about the cardiac manifestations of sarcoidosis:

1. Sarcoidosis is considered an immunological disorder. Approximately 5% of patients with sarcoidosis have clinically manifest cardiac involvement and another 20–25% have asymptomatic cardiac involvement (clinically silent disease). Lungs are involved in about 90% of the patients. Cardiac sarcoidosis (CS) may be the first manifestation of sarcoidosis in any organ, and generally the prognosis is worse when the heart is involved.
2. Echocardiographic abnormalities tend to be nonspecific and variable; interventricular thinning (particularly basal) is the most typical feature of CS. Less commonly an increase in myocardial wall thickness may be seen, simulating left ventricular (LV) hypertrophy or hypertrophic cardiomyopathy.
3. Cardiac magnetic resonance (CMR) imaging shows no specific pattern of late gadolinium enhancement (LGE) and is diagnostic for CS, although typically it is multifocal and patchy, with sparing of the endocardial border. The extent of LGE is emerging as an important prognostic factor.
4. Focal or focal-on-diffuse fluorodeoxyglucose (FDG) uptake patterns on cardiac positron emission tomography (PET) suggest active disease.
5. Historical sarcoidosis biomarkers, circulating angiotension-converting enzyme, and lysozyme, are frequently measured in suspected CS, but their utility is limited. In one study, 67% of patients with new-onset disease had elevated highly sensitive troponin levels, which normalized after 4 weeks of steroid therapy.
6. Due to the focal nature of the disease, endomyocardial biopsy has low sensitivity rates. However, electrophysiological (electroanatomic mapping) or imaging (PET or CMR)-guided biopsy procedures are now recommended by consensus guidelines because positive biopsy rates have increased to 50% with these techniques.
7. There are scarce data to compare the specificity and sensitivity of screening tests for cardiac involvement in patients with extracardiac sarcoidosis.
8. None of the diagnostic criteria proposed by Heart Rhythm Society Consensus Guidelines have been prospectively validated. There are still many unknowns in terms of best practices in diagnosing and managing CS patients. Consider sarcoidosis when there is unexplained arrhythmias, heart block, shortness of breath, or syncope.
9. Immunosuppression therapy usually with corticosteroids has been suggested therapy of clinically manifest CS despite disparate data on efficacy. Methotrexate has been used as a second-line agent when steroids fail; however, the results are not consistent.
10. CS carries a risk of sudden death, but data to support risk stratification are scarce. Due to underlying scarring, the efficacy of antiarrhythmic drugs and ablation of underlying rhythm disorders has been suboptimal. Patients with clinically manifest disease often need device therapy, typically with implantable cardioverter-defibrillators.

Keywords: Anti-Arrhythmia Agents, Arrhythmias, Cardiac, Biomarkers, Biopsy, Cardiomyopathies, Cardiomyopathy, Hypertrophic, Death, Sudden, Defibrillators, Implantable, Dyspnea, Echocardiography, Fluorodeoxyglucose F18, Gadolinium, Heart Failure, Hypertrophy, Left Ventricular, Magnetic Resonance Imaging, Positron-Emission Tomography, Sarcoidosis, Steroids, Syncope, Troponin

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