CMR-guided ICD in Non-ischaemic DCM — EECC MCQ

Correct answer: B — Extensive LGE (≥5% of LV mass) in non-ischaemic DCM is associated with a 3-5 fold increase in arrhythmic events and all-cause mortality, independent of LVEF — the presence of LGE strengthens the ICD indication (from Class IIa without LGE to supported Class IIa with LGE, even at LVEF 35-50%)

CMR with LGE assessment has become central to risk stratification in non-ischaemic DCM. The 2023 ESC Cardiomyopathy Guidelines explicitly incorporate LGE: (1) LGE ≥5% of LV mass = independently predicts SCD, sustained VT/VF, and all-cause mortality (3-5 fold risk increase); (2) at LVEF ≤35%: LGE supports the Class IIa ICD recommendation (stronger evidence than without LGE); (3) at LVEF 35-50% with extensive LGE: ICD may be considered (the traditional 35% threshold may miss high-risk patients with significant scar). The mid-wall septal LGE pattern is characteristic of non-ischaemic DCM and reflects replacement fibrosis serving as a substrate for re-entrant ventricular arrhythmias. The CMR-GUIDE trial (ongoing) is prospectively evaluating LGE-guided ICD decisions in LVEF 36-50%. Native T1 and ECV may provide additional prognostic information beyond focal LGE.

Reference: ESC (2023): Cardiomyopathies Guidelines