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LGE as SCD Risk Modifier in HCM — EECC MCQ

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ModerateCardiomyopathyLGE as SCD Risk Modifier in HCMEECC

A 40-year-old man with HCM undergoes cardiac MRI which shows extensive LGE involving 22% of the LV mass. His HCM Risk-SCD 5-year score is 4.5% (intermediate). How does the LGE extent influence the ICD decision?

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Correct answer: E — Extensive LGE (≥15% of LV mass) is a risk modifier not captured by the ESC HCM Risk-SCD calculator; it upgrades the risk assessment and strengthens the case for ICD implantation even in the intermediate risk zone (4-6%)

The ESC HCM Risk-SCD calculator does not include CMR LGE as a variable (it was developed before widespread CMR use). However, the 2023 ESC Cardiomyopathy Guidelines explicitly identify extensive LGE (≥15% of LV mass) as a risk modifier that should be considered alongside the calculator score. In the intermediate risk zone (4-6%), extensive LGE upgrades the risk assessment toward ICD implantation (Class IIa when combined with other risk modifiers). The evidence: multiple studies and a large meta-analysis by Weng et al. showed that LGE ≥15% of LV mass is associated with a 2-3 fold increase in SCD risk. Other risk modifiers beyond the calculator include: LV apical aneurysm, LVEF <50%, and arrhythmogenic genotypes (LMNA-like high-risk variants are rare in HCM but should be considered).

Reference: ESC (2023): Cardiomyopathies Guidelines