Prospective Evaluation of ICI Myocarditis: Late Gadolinium Enhancement Predicts Mortality (RF_FR_400)

Cardiac magnetic resonance (CMR) imaging plays an emerging role in diagnosing immune checkpoint inhibitor (ICI)-associated myocarditis, yet prospective data on its prognostic utility remains limited. This study aimed to assess whether the extent of late gadolinium enhancement (LGE) on CMR could predict mortality in patients with ICI myocarditis.

Methods: In this prospective cohort study, patients diagnosed with ICI myocarditis underwent CMR at the time of diagnosis. LGE was quantified using a signal intensity threshold of six standard deviations above adjacent normal myocardium. We analyzed the relationship between LGE burden and mortality.

Results:

A total of 46 patients with confirmed ICI myocarditis were enrolled. The mean age was 68 years (IQR: 62–76), with 52% female, 78% white, 20% Black, and 2% Asian. The mean percentage of LGE was 9.1%. Receiver operating characteristic (ROC) analysis identified a 3% LGE threshold as the optimal cut-off for predicting mortality (AUC 60%, sensitivity 86%, specificity 44%). Kaplan-Meier analysis demonstrated a significant difference in survival between patients with LGE below versus above this threshold (HR: 3.2, 95% CI: 0.94–10.89, p = 0.049). The median follow-up duration was 435 days.

Conclusion: Our study found that a higher LGE burden on CMR is associated with increased mortality during follow-up in patients with ICI myocarditis. These findings suggest that the extent of LGE on CMR is a potential predictor of mortality. Larger, prospective studies are needed to further refine CMR-derived prognostic markers in this high-risk population.