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CMR in Immune Checkpoint Inhibitor-Associated Myocarditis
Study Questions:
What are the cardiovascular magnetic resonance (CMR) characteristics, the correlation between CMR findings and histopathology, and the association between CMR features and cardiovascular events among patients with immune checkpoint inhibitor (ICI)-associated myocarditis?
Methods:
The investigators collected clinical, CMR, and histopathological findings from an international registry of patients with ICI-associated myocarditis. Major adverse cardiovascular events (MACE) were a composite of cardiovascular death, cardiogenic shock, cardiac arrest, and complete heart block. Cox proportional hazards models were performed to examine the association of CMR and histopathology features with MACE. Harrell’s C-statistics were obtained to assess the performance of the survival models.
Results:
In 103 patients diagnosed with ICI-associated myocarditis who had a CMR, the mean left ventricular ejection fraction (LVEF) was 50%, and 61% of patients had an LVEF ≥50%. Late gadolinium enhancement (LGE) was present in 48% overall, 55% of the reduced EF, and 43% of the preserved EF cohort. Elevated T2-weighted short tau inversion recovery (STIR) was present in 28% overall, 30% of the reduced EF, and 26% of the preserved EF cohort. The presence of LGE increased from 21.6%, when CMR was performed within 4 days of admission, to 72.0% when CMR was performed on day 4 of admission or later. Fifty-six patients had cardiac pathology. LGE was present in 35% of patients with pathological fibrosis, and elevated T2-weighted STIR signal was present in 26% with a lymphocytic infiltration. Forty-one patients (40%) had MACE over a follow-up time of 5 months. The presence of LGE, LGE pattern, or elevated T2-weighted STIR was not associated with MACE.
Conclusions:
The authors concluded that their data suggest prudence in reliance on LGE or a qualitative T2-STIR-only approach for the exclusion of ICI-associated myocarditis.
Perspective:
The current study reports that more than half of the cases of ICI-associated myocarditis presented with a preserved LVEF with LGE present in less than half of patients and was less among those with a preserved LVEF. Also, qualitative myocardial edema by T2-weighted STIR was present in less than one-third of patients. Furthermore, the correlation between LGE and pathological fibrosis and between myocardial edema by T2-weighted STIR and lymphocytic infiltration were, at best, modest. These data suggest prudence be exercised if using an LGE or qualitative T2-weighted STIR imaging-only approach to diagnose or exclude ICI-associated myocarditis, especially among the majority of patients with normal LVEF, and further suggest that when there is a strong clinical suspicion of myocarditis, a biopsy be considered in those with a negative CMR. Additional larger studies with longer follow-up time are indicated to validate these results.
Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Acute Heart Failure, Magnetic Resonance Imaging
Keywords: Biopsy, Contrast Media, Diagnostic Imaging, Edema, Fibrosis, Gadolinium, Heart Arrest, Heart Block, Heart Failure, Magnetic Resonance Imaging, Myocarditis, Myocardium, Secondary Prevention, Shock, Cardiogenic, Stroke Volume, Ventricular Function, Left
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