Frequency of Late Gadolinium Enhancement-Negative Cardiac Magnetic Resonance Imaging at Initial Presentation with Metabolically Active Treatment-Naïve Cardiac Sarcoidosis

Aims The 2024 American Heart Association statement recommends fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) for patients with high clinical suspicion of cardiac sarcoidosis even without late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR), but this recommendation has been challenged. We determined the frequency of LGE-negative CMR at first presentation of clinically manifest, metabolically active, treatment-naïve cardiac sarcoidosis. Methods and Results In this single-center sub-study of the prospective Cardiac Sarcoidosis Multi-Center Prospective Cohort Study, we analyzed 46 consecutive treatment-naïve patients with de novo clinically manifest cardiac sarcoidosis and core-laboratory-defined abnormal cardiac and extracardiac FDG uptake, imaged within a 6-month interval, before immunosuppression. Four of 46 patients had no LGE on CMR (8.7%; exact 95% CI, 2.4–20.8%). All four presented with advanced atrioventricular conduction disease and none had ventricular tachycardia; three of four started immunosuppressive therapy. Compared with LGE-positive patients, LGE-negative patients had preserved left ventricular ejection fraction and lower cardiac inflammatory burden (left ventricular maximum standardized uptake value 3.9 ± 0.9 vs 9.6 ± 5.2; P=0.037). Conclusion An LGE-negative phenotype can occur in clinically relevant, treatment-naïve, FDG-avid cardiac sarcoidosis. These findings suggest considering FDG-PET in selected patients with high clinical suspicion of cardiac sarcoidosis, even when CMR shows no LGE.