Cardiac MRI Features and Prognostic Value in Immune Checkpoint Inhibitor-induced Myocarditis

Background: Cardiac MRI features are not well-defined in immune checkpoint inhibitor (ICI)-induced myocarditis (ICI-M), a severe complication of ICI therapy in patients with cancer. Purpose: To analyze the cardiac MRI features of ICI-M and to explore their prognostic value in major adverse cardiovascular events (MACE). Materials and Methods: In this retrospective study from May 2017 to January 2020, cardiac MRI findings (including late gadolinium enhancement [LGE], T1 and T2 mapping, and extracellular volume fraction [ECV] z scores) of patients with ICI-M were compared with those of patients with cancer scheduled to receive ICI therapy (pre-ICI group) and patients with viral myocarditis. As a secondary objective, the potential value of cardiac MRI for predicting MACE in patients with ICI-M by using Cox proportional hazards models was explored. Results: Thirty-three patients with ICI-M (mean age +/- standard deviation, 68 years +/- 14; 23 men) were compared with 21 patients scheduled to receive to ICI therapy (mean age, 65 years +/- 14; 14 men) and 85 patients with viral myocarditis (mean age, 32 years +/- 13; 67 men). Compared with the pre-ICI group, patients with ICI-M showed higher global native T1, ECV, and T2 z scores (0.03 +/- 0.85 vs 1.79 +/- 1.93 [P < .001]; 1.34 +/- 0.57 vs 2.59 +/- 1.97 [P = .03]; and -0.76 +/- 1.41 vs 0.88 +/- 1.96 [P = .002], respectively), and LGE was more frequently observed (27 of 33 patients [82%] vs two of 21 [10%]; P < .001). LGE was less frequent in patients with ICI-M than those with viral myocarditis (27 of 33 patients [82%] vs 85 of 85 [100%]; P < .001) but was more likely to involve the septal segments (16 of 33 patients [48%] vs 25 of 85 [29%]; P < .001) and midwall layer (11 of 33 patients [33%] vs two of 85 [2%]; P < .001). Septal LGE was the only cardiac MRI predictor of MACE at 1 year even after adjustment for peak troponin (adjusted hazard ratio, 2.7 [95% CI: 1.1, 6.7]; P = .03). Conclusion: Cardiac MRI features of immune checkpoint inhibitor (ICI)-induced myocarditis (ICI-M) seem to differ from those in patients scheduled to receive ICIs and patients with viral myocarditis. Septal late gadolinium enhancement might be a predictor of major cardiovascular events in patients with ICI-M. (C) RSNA, 2022