The role of sex, training load, and sports type in athletic cardiac remodelling: Insights from T1 and T2 mapping via cardiac magnetic resonance

BACKGROUND: Cardiovascular magnetic resonance (CMR) imaging, utilising native T1 and T2 mapping, provides a non-invasive method for assessing myocardial tissue properties, contributing to the clinical evaluation of the athlete's heart. OBJECTIVE: To evaluate T1 and T2 mapping alterations and their association with sex, training volume, sports type, and other standard CMR parameters of the athlete's heart. METHODS: We conducted a cross-sectional analysis of healthy elite athletes (≥10 training hours/week) and sedentary controls (≤5 h/week) who underwent detailed cardiology screening. CMR was performed, and native T1 and T2 values were quantified. RESULTS: Of the 199 healthy participants (115 elite athletes, 24 ± 5 years, 70 % males; 84 sedentary volunteers, 26 ± 3 years, 58 % males), athletes had higher ventricular volumes, left ventricular mass (LVMi), and lower ejection fractions than volunteers. Athletes showed lower T1 values (male athletes:941 ± 23 ms vs. 960 ± 21 ms, p < 0.01; female athletes:970 ± 20 ms vs. 982 ± 25 ms, p < 0.01). T1 negatively correlated with training hours and LVMi (Rho: -0.554, p < 0.001). T1 values were positively associated with female sex with 22 ms (CI 14.3, 29.7, p < 0.001) higher values than males, while each additional hour in weekly exercise volume was associated with a 0.5 ms (CI -0.84, -0.11, p = 0.011) decrease. Compared to strength and mixed athletes, endurance athletes showed more pronounced myocardial adaptation, reflected in lower T1. CONCLUSION: Sex, training volume, and type of sport significantly influence CMR-derived T1 and T2 values. This study highlights the critical need for sex- and sport-type-specific reference ranges in assessing myocardial remodelling in athletes, facilitating the distinction between benign athletic remodelling and (early) pathological changes.