Real-world comparison of contemporary diagnostic criteria for cardiac sarcoidosis: a three-year experience at a tertiary referral center

Sarcoidosis is a chronic systemic inflammatory disease of unknown aetiology characterized by non-caseating epithelioid granulomas. Although it most commonly presents with hilar lymphadenopathy or pulmonary infiltration, clinically overt cardiac involvement occurs in approximately 5% of cases and is associated with an increased arrhythmic burden and systolic dysfunction. Subclinical myocardial involvement may precede overt clinical manifestations. The relatively low reported prevalence likely reflects underdiagnosis and heterogeneity among existing diagnostic criteria. This study aimed to provide a real-world evaluation of four major diagnostic frameworks for cardiac sarcoidosis (CS): the 2014 Heart Rhythm Society (HRS), the 2016 Japanese Circulation Society (JCS), the 2014 World Association of Sarcoidosis and Other Granulomatous Disorders (WASOG), and the 2024 American Heart Association (AHA) criteria. Between February 2023 and February 2026, 67 consecutive patients were evaluated at our Clinic. All patients underwent comprehensive assessment, including cardiac magnetic resonance (CMR) with late gadolinium enhancement (LGE) and FDG-PET. Four patients with suspected isolated CS underwent endomyocardial biopsy, which was negative in all cases. Sixty-one patients (91%) had histologically confirmed extracardiac sarcoidosis. According to the 2014 HRS and WASOG criteria, respectively 19 (28%) and 20 patients (30%) met the definition of clinical CS, while 17 (25%) fulfilled the 2016 JCS criteria. Based on the 2024 AHA framework, 9 patients were classified as having highly probable CS due to CMR evidence of a typical non-ischaemic LGE pattern consistent with CS in the presence of extracardiac sarcoidosis and clinically relevant cardiac manifestations. Eleven patients were classified as probable CS based on a typical LGE pattern on CMR in the setting of extracardiac sarcoidosis without additional major clinical features. Four patients were categorized as probable isolated CS based on CMR findings highly suggestive of CS (patchy, multifocal non-ischaemic LGE and/or myocardial oedema) in the absence of confirmed extracardiac disease. Overall, 24 patients (36%) were diagnosed with CS according to the 2024 AHA criteria. Although CS remains diagnostically challenging, our findings support the central role of CMR and FDG-PET in identifying myocardial involvement, particularly at a subclinical stage, whereas endomyocardial biopsy demonstrated limited diagnostic yield. According to the 2024 ESC consensus, CS may present not only as clinically manifest disease but also in a subclinical form, warranting structured follow-up; in this context, advanced imaging modalities play a fundamental role. The 2024 AHA criteria may provide greater flexibility and diagnostic granularity; however, multicentre validation is warranted.