BackgroundCurrent guidelines present varying classes of recommendations for implantable cardioverter-defibrillator (ICD) utilization in patients with cardiac sarcoidosis (CS) and left ventricular ejection fraction (LVEF) <50%. ObjectiveTo investigate the ventricular arrhythmia risk in CS patients with ICDs and varying degrees of LV systolic dysfunction. MethodsWe included CS patients with an ICD and LVEF <50% at index evaluation. The primary outcome was survival free of sustained ventricular tachycardia/fibrillation (VT/VF) after ICD implantation and was assessed comparatively for LVEF ≤35 vs 36-49% and for primary vs secondary prevention ICD indication. ResultsWe included 61 patients (median age 57 years, 61% male) with LVEF 36-49% (n=23) or LVEF ≤35% (n=38). An ICD was implanted for secondary prevention in 24% and 44% of the LVEF ≤35% and 36-49% groups, respectively (p=0.11). The primary outcome did not differ between the two groups in univariable analysis (LVEF ≤35% vs 36-49% HR 0.85 [95% CI 0.39, 1.82], p=0.67). In multivariable analysis, secondary prevention ICD indication was the only significant predictor of incident sustained VT/VF (HR 2.86 [95% CI 1.23, 6.67], p=0.015). The mean sustained VT/VF event burden was higher in the secondary as compared with the primary prevention ICD patients (0.47 vs 0.11 events/patient-year, p=0.005) but did not differ significantly between LVEF ≤35% and 36-49% patients. ConclusionsCS patients with ICD indications and LVEF 36-49% carry similarly high arrhythmic risk as those with LVEF ≤35%. Patients with secondary prevention ICDs have the highest overall risk.