Table 2.

Japanese Circulation Society 2016 Guideline on diagnosis of cardiac sarcoidosis.

1. Histological diagnosis

CS is diagnosed when a biopsy (endomyocardial or surgical) shows non-caseating epithelioid granulomas

2. Clinical diagnosis

If an endomyocardial biopsy is not performed or is negative, a diagnosis is made clinically.

CS is diagnosed clinically (1) when epithelioid granulomas are found in organs other than the heart, and clinical findings strongly suggestive of cardiac involvement by CS are present; or (2) when there is evidence of pulmonary or ophthalmic sarcoidosis and there are $\ge$2 characteristic laboratory and imaging findings and clinical findings strongly suggestive of cardiac involvement ($\ge$2 major or $\ge$1 major and $\ge$2 minor criteria)

Criteria for cardiac involvement

Clinical findings that satisfy $\ge$2 major or $\ge$1 major and $\ge$2 minor criteria strongly suggest CS

1. Major criteria

(a) High-grade AV block or fatal ventricular arrhythmia (VF and sustained VT)

(b) Basal thinning of the ventricular septum or abnormal ventricular wall anatomy including ventricular aneurysm, thinning of the middle or upper ventricular septum, regional ventricular wall thickening

(c) LVEF 50% or focal ventricular wall asynergy

(d) 67Ga citrate scintigraphy or 18F-FDG-PET revealing abnormally high tracer accumulation in the heart

(e) Cardiac MRI reveals LGE of the myocardium

2. Minor criteria

(a) Abnormal ECG findings: ventricular arrhythmias including NSVT, multifocal or frequent PVCs, BBB, axis deviation or abnormal Q waves

(b) Myocardial perfusion scintigraphy (SPECT) showing perfusion defects

(c) Endomyocardial biopsy showing infiltration with monocytes and moderate to severe myocardial interstitial fibrosis

Characteristic laboratory and imaging findings in sarcoidosis

A diagnosis of sarcoidosis is established when $\ge$2 of the following findings are observed:

1. High serum ACE activity or elevated serum lysozyme levels

2. High serum soluble interleukin-2 receptor levels

3. Increased tracer uptake in 67Ga citrate scintigraphy or 18F-FDG- PET

4. A high percentage of lymphocytes in BAL with a CD4/CD8 ratio of $>$3.5

5. Bilateral hilar lymphadenopathy

Isolated CS diagnostic guidelines

Isolated CS is suspected when:

1. No clinical findings are suggestive of other organ involvement than the heart

2. Absence of increased uptake in 67Ga or 18F-FDG-PET in any organs other than the heart

3. A chest CT scan reveals no shadow along the lymphatic tracts in the lungs or no hilar and mediastinal lymphadenopathy

Isolated CS is diagnosed with:

1. Histological diagnosis: endomyocardial biopsy or surgical biopsy show non-caseating epitheloid granulomas

2. Clinical diagnosis: isolated CS diagnosis is made when criteria for cardiac involvement 1(d) and $\ge$3 of the 1(a), (b), (c), (e) are satisfied

Adapted from [8] with modifications.

AV, atrioventricular; ACE, angiotensin-converting enzyme; BAL, bronchoalveolar lavage; BBB, bundle branch block; CS, cardiac sarcoidosis; LGE, late gadolinium enhancement; LVEF, left ventricular ejection fraction; NSVT, non-sustained ventricular tachycardia; PVC, premature ventricular complex; VF, ventricular fibrillation; VT, ventricular tachycardia; ECG, electrocardiogram; MRI, magnetic resonance imaging; CT, computed tomography; ECG, electrocardiogram; SPECT, single-photon emission computed tomography; CD4, helper T lymphocytes; CD8, cytotoxic T lymphocytes; FDG-PET, 18F-fluorodeoxyglucose positron emission tomography.