Funding Acknowledgements Type of funding sources: None. Purpose Aortic dilatation is associated with acute aortic pathology. Cardiac magnetic resonance (CMR) data in asymptomatic elite athletes is lacking. Therefore, we investigated the prevalence of aortic dilatation in a cohort of elite-level athletes using CMR. Methods We performed a cross-sectional study of aortic dimensions among elite-level (national-, international-, Olympic-, Paralympic-level or comparable) athletes. All athletes were asymptomatic and examined during pre-participation screening. Each underwent CMR with 3D whole heart in diastole (1.5 mm voxel) for aortic measurements, next to cine imaging, late gadolinium enhancement (LGE), and T1-mapping. We defined dilatation as 38 and 40 mm at the aortic root (sinus of Valsalva cusp-cusp), 27 and 31 mm at the sinotubular junction, and 23 and 26 mm at the level of the diaphragm, in male- and female athletes, respectively. Athletes were grouped for having 0- (normal), 1-, 2- or 3 measurements above cut-off values. Results We screened 156 athletes, 41% female, with a mean age (±SD) of 28±7 and body surface area (BSA) of 2.0±0.2 m2. Mean aortic dimensions were 33±4 mm for the sinus of Valsalva, 28±3 mm for the sinotubular junction, 20±3 mm for the aorta at diaphragm. We observed indexed end-diastolic volumes (EDVi) of 122±20 and 123±20 ml/m2, indexed end-systolic volumes (ESVi) of 53±13 and 54±16 ml/m2, stroke volumes (SV) of 129±36 and 126±39 ml, and ejection fractions (EF) of 56±5 and 55±6 %, in the left- (LV) and right ventricle (RV), respectively Fifty-three (34%) athletes, of which 45% female, had 1 or 2 aortic measurements above conventional cut-off values (Table 1). Eleven (7%), 18% female, had 2 aortic measurements above cut-off values. No athlete had all 3 measurements above cut-offs values. Athletes with 2 dilated measurements compared to athletes with 1 or 0 dilated measurements, had greater LV EDVi (145±19 vs. 119±18 vs. 120±19 ml/m2, p<0.001), greater RV EDVi (142±18 vs. 119±17 vs. and 122±20 ml/m2, p=0.002), greater LV ESVi (66±10 vs. 51±13 vs. 52±13 ml/m2, p=0.002), greater RV ESVi (66±10 vs. 53±13 vs. 53±17 ml/m2, p=0.039), greater LV SV (156±26 vs. 132±35 vs. 125±36 ml, p=0.020), and greater RV SV (152±25 vs. 130±34 vs. 121±41 ml, p=0.031), 2- vs, 1- vs. 0 dilated segments, respectively (Table 1, Figure 1). Athletes with dilated measurements had no LGE (excluding the hinge point), no difference in T1-mapping times, or LV- and RV EF, compared to athletes without dilated measurements. Conclusion One in three elite-athletes has dilatation in one or more aortic segments, including the sinus of Valsalva, sinotubular junction, or the aorta at diaphragm. Athletes with 2 dilated measurements (7%) had greater LV- and RV EDVi, ESVi, and SV, suggesting an association with ventricular volumes. Our findings in asymptomatic elite athletes, with normal EF and no LGE and comparable T1-mapping times, could be a sign of an outspoken physiological sports adaptation, instead of pathology.

Funding Acknowledgements Type of funding sources: None. Background Late gadolinium enhancement (LGE) demonstrates regional differences in myocardial extracellular volume, such as seen in myocardial fibrosis, and is associated with diverse cardiac diseases and is a predictive factor for sudden cardiac death. Earlier findings suggest an LGE prevalence of 7% in endurance athletes of varying age and exercise exposure. However, findings for (potentially benign) LGE indices in athletes performing at elite-level are lacking. Purpose To establish a specific baseline for LGE findings on CMR in apparently healthy, elite-level athletes. Methods We performed a cross-sectional assessment of hinge point late gadolinium enhancement (HP-LGE) in elite athletes (national-, international-, Olympic-, Paralympic-level or comparable). All athletes were asymptomatic and examined during pre-participation cardiovascular screening. Each underwent CMR using 3 Tesla- (Philips) or 1½ Tesla- (Siemens) MRI-scanners including short-axis cine imaging, LGE, and T1-mapping. CMR data were analysed using cvi42, statistical analyses using R. Athletes with HP-LGE were compared to athletes without HP-LGE. Results We screened 210 athletes, 34% female, with a mean age (±SD) of 28±7 and body surface area (BSA) of 2.0±0.2 m2 participating in road cycling (n=38), field hockey (n=28), water polo (n=27), soccer (n=21), rowing (n=18), swimming (n=13), track cycling (n=12), tennis (n=10), sailing (n=10), para-cycling (n=7), and miscellaneous (n=26) sports. We observed indexed end-diastolic volumes (EDVi) of 119±20 and 123±20 ml/m2, stroke volumes 131±33 and 127±37 ml, and ejection fractions of 56±5 and 54±6 %, in the left- (LV) and right ventricle (RV), respectively. Eighty-four (40%) athletes had HP-LGE. Proportionally, fewer female athletes had HP-LGE as compared with men (24 vs 41 %, p=0.014). Athletes with HP-LGE had greater LV- and RV EDVi (123±20 and 127±20 ml/m2 vs. 117±19 and 120±19 ml/m2, p=0.02 and p=0.01; for LV and RV, respectively), lower RV ejection fractions (53±5 vs. 55±6, p-value 0.04), smaller estimated global extra cellular volumes of the LV (24 vs 25 %, p=0.01). There were no differences in indexed LV- and RV end-systolic volumes, LV- and RV stroke volumes, LV ejection fraction and indexed wall mass, global native-, or contrast-enhanced T1 times in athletes with and without HP-LGE. Conclusion Late gadolinium enhancement in the hinge point is present in 40% of asymptomatic elite athletes. Athletes with HP-LGE were more frequently men, had higher LV- and RV EDVi, suggesting an association with ventricular volumes. Our findings in asymptomatic, elite athletes, with normal ventricular function and T1 times, suggest that HP-LGE could be a sign of physiological sports adaptation instead of an early sign of pathology. Further studies are warranted to investigate if HP-LGE is associated with long-term cardiac changes or the development of cardiac pathology.