Prognosis and Outcomes of Clinically Diagnosed Cardiac Sarcoidosis Without Positive Endomyocardial Biopsy Findings

Background: Diagnosis of cardiac sarcoidosis (CS) is sometimes difficult due to a low positive rate of epithelioid granulomas by endomyocardial biopsy (EMB). Accordingly, Japanese guidelines can allow the CS diagnosis using clinical data alone without EMB results (clinical CS) since 2006. However, little is known about prognosis and outcome of clinical CS. Objectives: Purpose of this study was to analyze the prognosis, outcomes, and response to corticosteroid of clinical CS using large-scale cohort survey. Methods: Overall, 422 CS patients (mean age 60 ± 13 years, 68% female, median follow-up period of 5 years), including 345 clinical CS and 77 EMB-positive patients, histologically diagnosed CS (histological CS) by Japanese guidelines, were enrolled and examined. Results: Clinical profile (age, sex, initial cardiac arrhythmias, and abnormal uptake of gallium-67 scintigraphy or ¹⁸F-fluorodeoxyglucose positron emission tomography in heart) was similar in both groups. Although clinical CS had better prognosis (P = 0.018) and outcome (all-cause death, appropriate defibrillator therapy, and heart transplantation; P = 0.008), multivariate Cox hazard analysis revealed that left ventricular ejection fraction (LVEF) and sustained ventricular tachycardia history were independently associated with outcome (P < 0.001 and P = 0.002, respectively), but not with the diagnosed CS category. Moreover, similar LVEF recovery after corticosteroid was observed in both groups with low LVEF (≤35%) at the 1-year follow-up period (P < 0.001). Conclusions: In clinical CS according to the Japanese guideline, prophylactic implantable-cardioverter-defibrillator and immunosuppressive therapy are important in patients with low LVEF or ventricular tachycardia history, similar to histological CS.