A longitudinal study of quantitative late gadolinium enhancement analysis in young athletes versus non-athletic individuals with acute myocarditis
Authors: Butt H , Androulakis E , Bhatia R , Maclachlan H , Sharma S , Papadakis M 
Published: June 2024

Abstract
Acute myocarditis is an acute inflammatory process within the myocardium, typically caused by infections, autoimmune disease, or drug reactions. Current guidelines suggest individuals with myocarditis should refrain from intense exercise, however, it remains unclear whether exercise affects myocardial properties and fibrosis during follow-up.
We analysed MRI's from 1,180 individuals referred to our dedicated Sports Cardiology service with evidence suggestive of acute myocarditis. After excluding individuals with fibrosis due to a possible arrhythmogenic cardiomyopathy, or other non-relevant causes, we identified 146 consecutive individuals with confirmed acute myocarditis: Group 1, N=57 young athletic individuals and Group 2, 89 non-athletes (table 1). All subjects underwent comprehensive appropriate evaluation in addition to cardiac magnetic resonance (CMR) with PSIR post contrast late gadolinium enhancement (LGE), at baseline and at follow up. Volumetric LGE quantification were derived by artificial intelligence-based techniques (Circle CVi42 Inc v5.13), making the necessary adjustments, and using 3 thresholding methods (2, 3, 5 SDs). Median follow-up was 71 months. Major adverse cardiovascular events (MACE), including heart failure, documented arrhythmias, recurrent myocarditis, heart transplant, stroke and death were recorded.
All patients included in this cohort were positive for LGE on admission CMR. LGE was found to be significantly reduced from baseline to the follow-up scan both in athletes (2SD; 24.6% (21.1-28.1) vs 19.7% (17.2-22.2), p&lt;0.001), and non-athletic individuals (2SD; 25.9% (22.9-29.0), vs 21.0% (18.9-23.1), p&lt;0.001). In the analysis of regional LGE distributions, the most common distribution of LGE that was observed in both groups was in the basal and mid inferolateral segments. Interestingly, lateral wall exhibited the highest proportion of LGE reduction at follow-up scan in the whole cohort, but anterior/antero-septal LGE did not reduce, particularly in athletes (Figure 1A+B). The overall rate of major adverse cardiac events was low with 10 out of the 146 cases (6.8%). There was no significant difference in MACE in athletes compared to non-athletes. Patients who developed an adverse event were found to have a higher proportion of LGE at presentation compared to patients who did not (22.7% vs 15.6%) and septal LGE signal was found to be significantly higher at presentation in patients who developed MACE (p&lt;0.05).
Young individuals with acute myocarditis showed significant improvement of fibrosis in the follow-up assessment, particularly in lateral walls; however, athletes exhibited different regression patterns in the anterior/anteroseptal walls, compared to non-athletic individuals. There was no significant difference in prognosis between the two groups, but patients with adverse events had larger amounts of fibrosis at presentation, particularly localized in the septumFigure 1 Table 1