20 Cardiovascular magnetic resonance to differentiate veteran athlete’s heart with cavity dilatation and mild dilated cardiomyopathy

<h3>Introduction</h3> Endurance athletes with left ventricular (LV) dilatation and mildly reduced resting LV function can be difficult to differentiate from dilated cardiomyopathy (DCM). Myocardial fibrosis is increasingly recognised in lifelong athletes and is also prevalent in DCM where it confers adverse prognosis. However, it is unknown whether the pattern and prevalence of fibrosis in athletes with cavity dilatation differs from DCM. We compared the CMR fibrosis distribution and tissue characteristics between athletic LV dilatation and mild DCM. <h3>Materials and Methods</h3> We prospectively recruited 113 male participants: 64 endurance athletes and 49 mild DCM patients. Inclusion criteria; Age 50–80 y, LVEF 45–54% and LV end-diastolic volume indexed to body surface area (LVEDVi) ≥110 ml/m2. Athletes trained ≥10 weekly hours for ≥15 y. Exclusion criteria; Chest pain, prior coronary revascularisation, severe valvular disease, myocarditis, hypertrophic cardiomyopathy, inducible ischaemia or myocardial infarction on CMR. CMR protocol included volumetric assessment, T1 mapping, quantitative stress perfusion and quantitative late gadolinium enhancement. Statistical analysis between groups was performed using unpaired t-test and receiver-operator curve (ROC) analysis. <h3>Results</h3> LVEDVi was not significantly different between athletes and mild DCM patients (123.3±12.6 vs 129.8±23.1 ml/m2, P=0.06). However, LVEF (52.0±6.1 vs 47.6±5.2%, P&lt;0.001) and right ventricular (RV) EDVi (121.0±14.3 vs 97.6±25.2 ml/m2, P&lt;0.001) were both greater in athletes. There was no difference in non-ischaemic fibrosis prevalence between both groups (50.0 vs 49.0%, P=0.92) nor the burden of fibrosis (3.5±2.9 vs 7.4±12.0 g, P=0.09). However, the distribution of fibrosis varied with a significantly greater prevalence of basal mid-myocardial inferolateral fibrosis amongst athletes (87.5 vs 50.0%, P=0.002) whereas basal mid-myocardial inferoseptal fibrosis was significantly more common in mild DCM patients (45.8 vs 9.4%, P=0.002). Native T1 (1249.0±38.1 vs 1308.3±47.1 ms, P&lt;0.001) and ECV (22.0±2.1 vs 25.9±3.5%, P&lt;0.001) were both lower in athletes than mild DCM patients. Furthermore, athletes had higher myocardial perfusion reserve (MPR) (3.65±1.30 vs 2.76±0.92, P&lt;0.001) and stress myocardial blood flow (MBF) (2.09±0.70 vs 1.62±0.66, P&lt;0.001). <h3>Discussion and Conclusion</h3> Myocardial fibrosis was highly prevalent in veteran endurance athlete’s heart and mild DCM whilst its distribution was distinctive between the groups. Native T1 and ECV were the best discriminators. Recognition of fibrosis patterns and associated tissue characteristics may be clinically useful to differentiate these two overlapping phenotypes. <h3>Acknowledgements</h3> Radiographers at the Advanced Imaging Centre, particularly Lizette Cash and David Shelley.