Late gadolinium enhancement prognostic value in hypertrophic cardiomyopathy
Authors: Florence J , Garot J , Toupin S , Unger A , Sanguineti F , Hovasse T , Goncalves T , Dillinger J G , Henry P , Clerfond G , Eschalier R , Bohbot Y , Bousson V , Garot P , Pezel T 
Published: January 2025

Abstract

Background
Late gadolinium enhancement (LGE) extent is the basis for risk stratification of hypertrophic cardiomyopathy (HCM) using cardiac magnetic resonance (CMR). LGE extent has been recently added in the guidelines by the European Society of Cardiology (ESC) and the American College of Cardiology (ACC), setting a threshold at ≥15% of left ventricular mass. However, SCD has become an uncommon event in this population, and mortality is now mostly related to other phenotypes, such as stroke and heart failure. While previous studies have showed the prognostic value of LGE to predict all-cause mortality, the prognostic impact of additional LGE features is not well established.

Purpose
We aimed to assess the prognostic value of the LGE granularity including extent, location, and pattern in HCM to predict all-cause death.

Methods
Between 2008 and 2021, all patients referred for HCM assessment using CMR, without history of coronary artery disease (CAD) or clinical history of myocarditis were prospectively recruited in two French centers. The outcome was all-cause death using the French National Registry of Death. The concept of LGE granularity was defined as a model combining LGE extent (by segment), location (septal or others), and pattern (midwall and/or subepicardial). Using nested Cox proportional hazard models, the additional predictive value of LGE granularity was assessed by the C-statistic increment, the continuous net reclassification improvement (NRI), the integrative discrimination index (IDI) and the global Chi-2.

Results
Among 2,672 patients (52±7 years, 56% males), 862 (32%) had LGE. After a median (IQR) follow-up of 9 (7–11) years, 447 (17%) patients died. Survival curves show an increased risk for LGE presence (log-rank p&lt;0.001, Figure 1A). After adjustment for traditional prognosticators in the overall population (N=2,672), LGE was associated with all-cause death (adjusted hazard ratio (HR) 3.96, 95% CI: 3.26-4.80, p&lt;0.001). Among the LGE subgroup (n=862), survival curves showed that the LGE granularity was associated with a higher risk of all-cause death (all p&lt;0.001, Figure 1B). A nested Cox model adjusted on traditional prognosticators showed that the LGE extent, location and pattern were all independently associated with all-cause death (all p&lt;0.001, Figure 2). The model of LGE granularity combining all independently significative LGE features showed the best improvement in model discrimination and reclassification above traditional prognosticators (C-statistic improvement: 0.90; NRI=41.9%; IDI=13.2%, Chi-2 global=450, all p&lt;0.001; LR-test p&lt;0.001, Figure 2).

Conclusion
In a large cohort of HCM patients, the LGE granularity model combining the extent, location, and pattern of LGE had an incremental prognostic value over and above traditional prognosticators to predict all-cause death.
Prognostic value of LGE in HCM
Incremental value of LGE granularity