Aleksi Alatalo

BACKGROUND: Cardiac sarcoidosis involves a significant but difficult-to-define risk of sudden cardiac death (SCD). Current guidelines recommend consideration of an implantable cardioverter defibrillator for patients with extensive or significant myocardial late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging. However, extensive/significant LGE is not defined. METHODS: A nationwide cardiac sarcoidosis registry was screened for patients entered before 2020 with cardiac magnetic resonance imaging done before or P <0.001), with receiver operating characteristic analyses identifying LGE mass ≥9.9% and ≥6 LGE segments as discriminative thresholds. At presentation, 70 patients were free of class I and class IIa implantable cardioverter defibrillator indications unrelated to LGE. Their 5-year rate of SCD/VT was 6.3% (0.0–14.8%) with LGE mass <9.9% versus 21.5% (6.5–36.6%) with higher LGE mass, and 6.9% (0.0–16.3%) with <6 LGE segments versus 20.5% (5.9–35.2%) with ≥6 segments. CONCLUSIONS: In cardiac sarcoidosis, myocardial LGE making up ≥9.9% of LV mass or affecting ≥6 LV segments may suggest prognostically significant LV involvement and a high risk of SCD. However, prospective validation of the thresholds is needed.