Native T1 mapping times are strongly influenced by elite athlete status.

Aims: Limited data indicates that athletes' hearts demonstrate decreased native T1, but this assertion has not been replicated in large cohorts of extreme phenotypes of elite athletes. Therefore, we investigated differences in native T1 between elite athletes and healthy non-athletic controls.

Methods And Results: Cross-sectional analysis comparing native T1 between elite athletes (≥16 years; ≥10 h of exercise/week) and age-matched healthy non-athletic controls. All participants underwent cardiovascular magnetic resonance imaging on a 1.5 tesla MRI machine. We included 240 elite athletes [50% women; age 28 years (25-32)] and 80 non-athlete healthy controls [50% women; age 28 years (23-39)]. Elite athletes demonstrated lower native T1 than non-athlete healthy controls (960 ± 21 ms vs. 983 ± 26 ms, P < 0.001), also when stratified by sex (male athletes vs. controls 953 ms ±19 vs. 968 ms ±16, P < 0.001; female athletes vs. controls 968 ms ±20 vs. 999 ms ±25, P < 0.001). Multivariate linear regression identified elite athlete status (β = -13.34, P < 0.001), heart rate (β = 0.6, P < 0.001), average left-ventricular wall thickness (β = -8.28, P < 0.001) and native blood pool T1 (β = 0.09, P < 0.001) as independent determinants of native T1 (adjusted R2 = 51.4%, P < 0.001).

Conclusion: Elite athletes have lower native T1 compared with non-athletes, both in women and men. Athlete- and sex-specific reference ranges should be applied when interpreting native T1 in athlete populations, especially in female athletes.