PROJECT SUMMARY/ABSTRACT An estimated 200,000 Americans live with sarcoidosis. Sarcoidosis is a multisystem granulomatous disease of unknown etiology. Up to a quarter of patients with sarcoidosis may have cardiac involvement. Cardiac sarcoidosis is the second leading cause of sarcoidosis-related mortality, accounting for up to a quarter of deaths from sarcoidosis. Most deaths from cardiac sarcoidosis are due to ventricular arrhythmias. Cardiovascular magnetic resonance imaging is frequently used in the evaluation of patients with suspected or known cardiac sarcoidosis. In this proposal, we aim to investigate cardiovascular magnetic resonance imaging biomarkers that may be associated with adverse outcomes in patients with suspected or known cardiac sarcoidosis. Using this information, we will identify integrative phenotypes – composed of biomarkers from cardiovascular magnetic resonance imaging, demographics, and clinical characteristics – associated with adverse cardiac outcomes. The proposed work will establish high- and low-risk phenotypes of cardiac sarcoidosis patients that predict benefit from immunosuppression and/or implantable cardioverter-defibrillators to prevent sudden arrhythmic cardiac death and other cardiac sarcoidosis-related adverse outcomes. These data will lay the groundwork for prospective studies testing the strategy of using the integrative phenotypes to select cardiac sarcoidosis patients for treatments. Selective and appropriate use of these treatments could improve long-term clinical outcomes in patients with cardiac sarcoidosis, in particular by preventing ventricular arrhythmia-related sudden cardiac death.