Persistence of Late Gadolinium Enhancement in Post-Acute Myocarditis Imaging

Background: Diagnosis of acute myocarditis (AM) is based on combining ECG and seromarkers, but endomyocardial biopsy (EMB) remains the gold standard. Cardiac Magnetic Resonance (CMR) has been established as a reference standard for the non-invasive diagnosis. CMR is useful for follow-up since it is able to non-invasively delineate the presence and extent of myocardial edema and myocardial left ventricle (LV) lesions, represented by late gadolinium enhancement (LGE). The follow-up depends on the individual scenario. The aim of this study is to correlate CMR findings with cardiac enzymes and inflammatory markers in patients with AM and to evaluate the utility of CMR follow-up, even after the resolution of the symptomatology.Methods: Between 2008 to 2016 thirty-three consecutive patients with clinical and laboratory suspicion of AM referred for CMR within seven days from the beginning of the symptoms. The final analysis included 24 patients with AM CMR-confirmed. The follow-up was performed between 3 and 24 months from the diagnosis. CMR was performed using a standard protocol. Presence of edema and extent of myocardial LGE were examined. The comparison between the proportion of patients affected by edema at onset and that of patients affected at the various follow-up was conducted through the test of Mc Nemar. The effect of the predictors on the outcome was evaluated with a nonparametric two-sample Wald test.Results: All patients showed edema and LGE at baseline CMR. The LV lateral wall resulted the most affected by edema (in particular the 12th segment), inferior and lateral wall of LV were the most involved by LGE. There was a highly significant effect (P<0.001) of the Troponin peak on the number of areas involved by LGE. At CMR follow-up, edema has resolved in all patients, LGE persisted in 23/24 patients.Conclusions: There is a correlation between the levels of troponin and myocardial LGE extension in baseline CMR but not between clinical conditions of the patients and post-myocarditis imaging. The presence and the extent of LGE in CMR follow-up are not predictive of outcome in patients without severe hemodynamic compromise, but it can be considered rather an early sign of poor prognosis.