Prognostic factors of fatal ventricular arrhythmias in cardiac sarcoidosis patients without a history of ventricular arrhythmias: insights from nationwide registry

Introduction Cardiac sarcoidosis (CS) has been associated with an elevated risk of fatal ventricular arrhythmias (VAs) events. Current guidelines provide recommendations for the primary prevention of implantable cardioverter defibrillator (ICS) implantation in patients with CS. However, the prognostic factors for fatal VAs events in CS without a history of VAs have not been fully investigated. Purpose This study aims to investigate the prognostic factors in patients with CS and without a history of VAs. Methods A nationwide registry was retrospectively enrolled patients who were diagnosed with CS between 2012 and 2021 based on the 2016 Japanese Circulation Society criteria. Patients who had a history of sustained ventricular tachycardia or fibrillation were excluded. The primary endpoint was a composite of sudden cardiac death, sustained ventricular tachycardia, ventricular fibrillation, and appropriate ICD therapy. Results Among a total of 2,366 patients, we identified 1,552 patients with CS who had no prior history of VAs (median age 63 years; 66% female). During a median follow-up of 1922 days (interquartile range, 1103 to 3091 days), the primary endpoint was observed in 139 patients (9.0%). Patients who experienced the primary endpoint had a higher prevalence of non-sustained ventricular tachycardia, elevated b-type natriuretic peptide levels, worse New York Heart Association functional class, higher prevalence of late gadolinium enhancement of cardiac magnetic resonance, and lower left ventricular ejection fraction (LVEF). There were no significant differences in the history of advanced atrioventricular block or the positron emission tomography findings between the two groups. Kaplan-Meier analysis revealed that patients with LVEF < 35% or LVEF 35%-50% had a higher risk of the primary endpoint compared to those with LVEF ≧ 50% (P < 0.001). Multivariate Cox regression analysis demonstrated that LVEF < 35% [hazard ratio (HR) 2.33, 95% confidence interval (CI) 1.22–4.46, P = 0.001] or LVEF 35%-50% (HR 1.90, 95% CI 1.07–3.35, P = 0.028), and history of non-sustained ventricular tachycardia (HR 1.89, 95% CI 1.17–3.04, P = 0.010) were independently associated with the primary endpoint. Conclusions Impaired LVEF, even within the range of 35-50%, and a history of non-sustained ventricular tachycardia were independently associated with an increased risk of fatal arrhythmic events in patients with CS.