Prospective Serial Cardiovascular Magnetic Resonance Imaging of Immune Checkpoint Inhibitor Myocarditis Correlates with Cardiovascular Outcomes

BACKGROUND: Limited prospective data exists on the utility of serial CMR imaging in immune checkpoint inhibitor (ICI) myocarditis. OBJECTIVES: To evaluate serial changes in CMR parameters and outcomes in patients with ICI myocarditis. METHODS: Patients were enrolled into two arms: 1) ICI myocarditis (ICI exposure with development of cardiac symptoms and abnormal cardiac biomarkers) or 2) pre-ICI control (patients planned to receive ICI therapy). Both cohorts received CMR imaging at the time of enrollment and upon follow up at 8-12 weeks. CMR parameters were associated with adverse cardiovascular outcomes (ACE). RESULTS: 62 patients were enrolled (N=52 in ICI myocarditis cohort; N=10 in pre-ICI control cohort). In those with ICI myocarditis, upon presentation, 38% of patients had a reduced LVEF (defined as -18%) with a mean GLS -10% (SD ± 5). Eighty five percent met at least one Lake Louise Criteria (LLC). Decreased LVEF at enrollment was associated with ACE (r =-0.437, p=0.002), as was increased CMR FT GLS and global circumferential strain (r=0.387, p=0.008 and r=0.439, p=0.002, respectively). Worse left atrial (LA) ejection fraction by CMR correlated with arrhythmia (r= -0.467, p= 0.051), and presence of LA LGE correlated with heart failure (r = 0.866, p= 0.012). Abnormal LA strain parameters, including contraction strain (r=0.611, p= 0.007) and reservoir strain (r= 0.543, p= 0.005) on follow up CMR were associated with death in those with ICI myocarditis. CONCLUSIONS: Baseline and serial CMR parameters are associated with incident ACE. Serial CMR evaluation may further risk stratify ICI myocarditis patients.