Cardiovascular Magnetic Resonance Late Gadolinium Enhancement Risk Score for Mortality in Patients with Hypertrophic Cardiomyopathy: the HCM-LGE Risk Score

Background: The concept of “late gadolinium enhancement (LGE) granularity” using cardiovascular magnetic resonance (CMR) has been described as a strong prognosticator for patients with cardiomyopathy.(1, 2) No score has been developed using LGE in patients with hypertrophic cardiomyopathy (HCM) for clinical routine.The aim of the study was to develop and validate a score using the “LGE granularity” concept to predict mortality in HCM patients.Methods: The study cohort was based on the multicentric HCM-LGE registry, that included 2,873 patients with HCM referred for CMR between 2008 and 2021 in three French centers. The HCM-LGE risk score was developed using multivariable Cox coefficients of the “LGE granularity” concept from the training cohort (N=1,609). Then, this score was evaluated by time-dependent AUCs, precision recall curves, and calibration at 5 years on testing (N=199) and external validation (N=272). The primary outcome was all-cause mortality using the French National Death Registry. Based on the HCM-LGE risk score, patients were classified into 3 risk groups: low-risk (≤3 points), intermediate-risk ( >3 and ≤5 points), and high-risk ( >5 points). Survival probabilities were estimated using the Kaplan-Meier method and compared with the log-rank test.Results: The HCM-LGE risk score showed good performance in time-dependent analysis, with AUC of 0.72 (95% CI: 0.65, 0.79) and precision-recall AUC of 0.52 (95% CI: 0.48-0.56) in the external validation cohort. Cox analysis showed escalating risk from intermediate-risk (aHR: 2.61, [95% CI: 1.33-5.15]) to high-risk patients (aHR: 3.50, [95% CI: 1.90-6.45]; both p< 0.001). The HCM-LGE risk score showed the best improvement in model discrimination and reclassification above traditional prognosticators (Harrell’s C-statistic improvement: 0.09; NRI=50%; IDI=17%, all p< 0.001).Conclusion: The HCM-LGE risk score is a straightforward and reliable mortality risk prediction score for patients with HCM using readily available LGE parameters, with an incremental prognostic value above traditional prognosticators.