The role of cardiac magnetic resonance (CMR in the follow-up after the acute myocarditis is unknown. The objectives of our study were to assess the evolution of CMR parameters between the acute phase of infarct-like myocarditis and 3 months thereafter.

All patients with chest pain associated with acute myocarditis confirmed by CMR [with typical delayed myocardial enhancement after gadolinium injection (LGE)] were included from April 2012 to October 2016. CMR was performed within 7 days following symptom onset and 3 months thereafter.

Eighty-five patients were included. The predominant location of LGE was anteroseptoapical in nine patients, infero-lateral in 63 patients and diffuse in 13 patients. Twenty-one patients (25%) had no significant (<10%) regression in LGE extent between the acute phase and 3 months The baseline factors significantly associated with absence of LGE regression were previous hypertension, a lower peak troponin value and a higher initial extent of LGE. Moreover, there was a trend toward significantly older patients and lower creatinine clearance in the group without LGE regression. After multivariate analysis, only an initial LGE extent >10% of the LV was significantly associated with absence of significant LGE regression at 3-month follow-up (OR: 3.52, 95%CI: 1.06–11.72, P=0.041). Moreover, when compared with patients experiencing significant LGE regression, those without significant LGE regression 3 months after the first CMR more often had adverse remodeling of the left ventricle as assessed by a delta end-systolic volume>10% (43% vs 16%, P=0.012).

Three months after acute “infarct-like” myocarditis, a high proportion of patient had no significant reduction in LGE extent. The relationship between 3-month CMR findings and the onset of clinical and functional outcomes at one-year follow-up will be evaluated soon.