Athletic cardiac remodeling and myocardial tissue characterization assessed by cardiac magnetic resonance derived T1 and T2 mapping

Background Cardiovascular magnetic resonance (CMR) imaging with native T1 and T2 mapping provides a non-invasive approach to assess myocardial tissue characteristics, playing a key role in evaluating the athlete’s heart. Objective To investigate alterations in T1 and T2 mapping values in athletes and examine their associations with sex, training volume, sport type, and cardiopulmonary adaptation. Methods In this cross-sectional study, we included healthy elite athletes (≥10 training hours/week) and sedentary controls (≤5 hours/week) who underwent comprehensive cardiovascular evaluation. Native T1 and T2 values were quantified using CMR imaging. In a subgroup of athletes cardiopulmonary exercise test was also performed. Results A total of 214 healthy participants (130 elite athletes, age 24 ± 5 years, 67% male; 84 sedentary controls, age 26 ± 3 years, 58% male) were included. Compared to controls, athletes exhibited higher ventricular volumes, increased left ventricular mass index (LVMi), and lower ejection fractions. T1 values were significantly lower in athletes (male athletes: 940 ± 23 ms vs. 960 ± 21 ms, p < 0.01; female athletes: 964 ± 20 ms vs. 982 ± 25 ms, p < 0.01). T1 values correlated negatively with training hours and LVMi (ρ = −0.554, p < 0.001). Female sex was associated with higher T1 values (mean difference: 22 ms; 95% CI: 14.3–29.7; p < 0.001), whereas each additional weekly training hour corresponded to a 0.5 ms decrease in T1 (95% CI: −0.84 to −0.11; p = 0.011). Endurance athletes demonstrated the most pronounced myocardial adaptations, reflected by the lowest T1 values compared to strength and mixed-sport athletes. In a subgroup of athletes undergoing cardiopulmonary exercise testing (n = 121), maximal oxygen uptake (VO₂max) emerged as the strongest independent predictor of T1 values (F = 5.84, p = 0.017). Conclusion Sex, training volume, and sport type significantly influence CMR-derived T1 and T2 values in athletes and VO2 max is a strong predictor of the T1 values. These findings underscore the necessity of sex- and sport-specific reference ranges to differentiate between physiological myocardial remodeling and early pathological changes in the athletic population.