Management and Outcomes of Cardiac Sarcoidosis: Insights From the Nationwide MYSTICS Registry

BACKGROUND: Cardiac sarcoidosis (CS) may lead to serious outcomes, but large-scale data are lacking because of its rarity, diagnostic uncertainty, and heterogeneous clinical presentations. Actual management and outcomes, including recurrence, are not well understood. This study aimed to clarify the actual management and outcomes of CS from a nationwide large-scale registry. METHODS: This multicenter retrospective registry enrolled 2366 consecutive patients with CS. Of these, 1852 patients newly diagnosed between 2012 and 2021 were analyzed. Patients were stratified into 4 groups: definite CS, probable CS, presumed systemic sarcoidosis, and presumed isolated CS based on diagnostic criteria. The primary end point was a composite of all-cause death, heart failure hospitalization, or fatal ventricular arrhythmic event. The secondary end point was recurrence of CS. RESULTS: Cardiac imaging performance rates were high (cardiac magnetic resonance: 64%, 18 F-fluorodeoxyglucose positron emission tomography: 82%), and 974 (53%) patients were diagnosed clinically without histological evidence. During a median 5.1-year follow-up, the primary outcome occurred in 519 (28%, 6.4/100 patient-years) patients, and the 4 groups exhibited different clinical presentations and prognoses; definite CS and presumed isolated CS groups showed a high incidence of the primary end point, fatal ventricular arrhythmic event, hospitalization for heart failure, and cardiovascular death. Most patients (89%) received immunosuppressive therapy, but 291 (18%, 4.1/100 patient-years) patients developed recurrence during steroid tapering, with a 5-year recurrence rate of 17.0%. Recurrence was associated with subsequent primary end point (hazard ratio, 1.38 [95% CI, 1.00–1.89]; P =0.048). CONCLUSIONS: This large-scale multicenter registry showed that clinical presentation and prognosis differ depending on the presence or absence of extracardiac lesions and histological evidence; therefore, it is necessary to recognize the characteristics of each phenotype in managing CS.