Clinical and cardiac magnetic resonance profile in patients with partial late gadolinium resolution at 6 months after acute myocarditis

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Cardiovascular magnetic resonance (CMR) is established as the gold standard non-invasive test for the diagnosis of acute myocarditis. However, current evidence on CMR after an acute myocarditis in the follow-up is contradictory. There are patients who can show an improvement on late gadolinium enhancement (LGE) extension but timing for CMR follow-up and the amount of this improvement is unclear. A better comprehension of patients’ profiles is therefore needed. Purpose To explore the clinical profile and index CMR findings in patients with acute myocarditis and persistent LGE in follow-up CMR focusing on the differences between those who present mild improvement (less than fifty percent of previously affected segments) versus patients who present a better improvement (more than fifty percent). Methods All patients with an acute myocarditis diagnosis from June 2021 to June 2022 and a follow-up CMR were retrospectively evaluated. Myocarditis was defined by modified Lake Louise criteria (mLLC). Electronic medical records were analyzed to collect data on baseline clinical variables, CMR features, treatment and follow-up events. A CMR was performed on follow-up based on clinician’s criteria. Results A total of 49 consecutive patients fulfilled updated LLC for myocarditis. 30 cases (61.2 %) had a follow-up CMR. The mean time to first CMR control was 186 +/- 95 days (6,2 months). After excluding patients with no LGE at index CMR, 22 patients were analysed. Of those, 13 had reduced LGE extent in less than fifty percent of previously affected segments, and 9 showed an improvement of more than fifty percent. There were no differences in cardiovascular risk factors or baseline comorbidities (Table 1). There were no differences between groups in terms of left and right ventricular ejection fraction. T1, T2 and ECV maps were similar en both groups. Patients with less LGE improvement tend to have more initial edema extension although this tendency was not statistically significant whilst there were no differences in LGE extension at index CMR. Both groups presented similar affected segments and in both cases inferolateral segments were the most affected (Table 2). There were no differences in clinical events after 13 months of mean follow-up time, there were no differences between groups regarding to corticoid, colchicine and NSAID prescription. Conclusions In our cohort, there were no differences in baseline characteristics, CMR findings, treatment and clinical events between patients with significant LGE improvement at 6 months after an acute myocarditis and those with only mild improvement.