When would you consider referring a patient with suspected cardiac sarcoidosis based on PET and MRI for endomyocardial biopsy given degree of patchy involvement, as opposed to initiating empiric immunosuppressive therapies?  

I would avoid initiating empiric immunosuppressive therapies without a firm diagnosis of sarcoidosis. I will mention however that the latest Japanese Circulation Society criteria for the diagnosis of sarcoidosis do include criterion for the non-invasive diagnosis of likely cardiac sarcoidosis based ...