In patients with newly diagnosed AV block and/or ventricular tachycardia, cardiac sarcoidosis should always be considered in the differential diagnosis. In addition to the pacemaker implant, cardiac resynchronization therapy (CRT) should be selected for severe heart failure patients who have class III or IV heart failure, LVEF <or=35%, and a complete LBBB pattern. If the disease activity is high, corticosteroid therapy is recommended. Patients with extracardiac sarcoidosis need to be closely followed for potential cardiac involvement, as the mortality in sarcoidosis depends on cardiac involvement. Early diagnosis and treatment of cardiac sarcoidosis is essential. Positron emission tomography (PET) and cardiac magnetic resonance imaging (MRI) are considered to have high sensitivity for cardiac involvement, and are the preferred imaging modalities. However, even in the era of new technology, such as PET and cardiac MRI, early diagnosis of cardiac sarcoidosis is still difficult.