The great mimicker: Multimodality imaging in cardiac sarcoidosis

Cardiac sarcoidosis is a granulomatous inflammatory disease that can mimic genetic cardiomyopathies, making diagnosis challenging, particularly in young patients with preserved ventricular function. Multimodality imaging is essential for identifying myocardial inflammation, assessing fibrosis, and stratifying arrhythmic risk.

We present the case of a 32-year-old female athlete evaluated for exertional syncope and initially suspected of having a genetic cardiomyopathy. Hybrid 18F-FDG PET–CMR demonstrated intense heterogeneous myocardial FDG uptake co-localizing with areas of late gadolinium enhancement (LGE), consistent with active inflammatory cardiomyopathy. Endomyocardial biopsy confirmed cardiac sarcoidosis. Following immunosuppressive therapy, inflammatory activity resolved, while myocardial fibrosis persisted.

This case highlights the value of hybrid PET–CMR in differentiating inflammatory from genetic cardiomyopathies, guiding biopsy, and refining sudden cardiac death risk assessment, even in patients with preserved left ventricular ejection fraction.