Late gadolinium enhancement persistence in early cardiac magnetic resonance follow-up after acute myocarditis

Abstract

Funding Acknowledgements Type of funding sources: None. Background Multiparametric cardiac magnetic resonance (CMR) evaluation with modified Lake Louise criteria (mLLC) is the gold standard non-invasive test for the diagnosis of acute myocarditis. Although CMR in the follow-up may inform of edema resolution and myocardial fibrosis there is a lack of consensus on the optimal time interval to perform it and the clinical and prognostic differences between patients with complete resolution and those who present late gadolinium enhancement (LGE) persistence. Purpose To describe the clinical profile, CMR findings, early CMR follow-up and clinical events in patients with acute myocarditis focusing on the differences between patients who present complete LGE resolution versus patients with LGE persistence. Methods All patients who underwent a CMR for a suspected myocarditis during a period of 1 year from June 2021 to June 2022 were retrospectively evaluated. Those with a confirmed myocarditis by mLLC and a follow-up CMR were included. Electronic medical records were analyzed to collect data on baseline clinical variables, CMR features and follow-up events. Follow-up CMR was performed on follow-up based on clinician’s criteria. Results A total of 27 patients fulfilled mLLC for myocarditis during the period of study and had a follow-up CMR. The mean time to first CMR control was 186 +/- 95 days (6,2 months). Of those 23 (85.2%) presented persistent LGE enhancement and 4 of them presented a complete resolution of LGE. There were no statistically significant differences between groups although patients with complete LGE resolution tend to be younger. There were no differences between groups in terms of LVEF and RVEF. Patients with persistent LGE in the follow-up tend to have higher edema and LGE extension during the acute myocarditis episode, being the LGE difference statistically significant. In the follow up CMR almost all patients presented edema resolution and although the majority of patients (85.2%) presented LGE persistence they presented a trend to a decrease of affected segments (4.4 to 3.1 after mean time of 6 months). There were no differences in clinical events between groups in terms of death, admissions, ventricular arrhythmias and new episodes of myocarditis, patients with persistent LGE tend to have more visits for unresolved chest pain. Conclusions The majority of patients with a confirmed acute myocarditis had edema resolution and LGE persistence after 6 months. There were no differences in clinical events during follow-up. Follow up CMR before 6 months can prove resolving edema but LGE persistance is common. Further studies are needed to define the optimal interval to perform CMR after the index event.