Redefining diastolic function reference limits in elite athletes: evidence from echocardiographic and biomarker correlates

Background In elite athletes, distinguishing between supranormal and pathological diastolic function (DF) can be challenging, as numerous diastolic dysfunction (DD) metrics overlap with physiological exercise-induced cardiac remodeling (EICR). To assist this differentiation, indices that characterize physiological DF in the context of EICR in athletes are needed. Purpose To characterize echocardiographic measures of DF in elite athletes, assess whether NT-proBNP levels are elevated in those exceeding standard DF reference values, and examine associations between DF metrics and the left atrial volumetric–mechanical coupling index (LACI-v/m) and atrioventricular coupling index (LACI-av). Methods Cross-sectional study in elite athletes (national, international, or Olympic level) with MRI-documented structurally normal hearts, included in the ELITE study. Athletes underwent a comprehensive clinical assessment and resting transthoracic echocardiography with tissue Doppler imaging to evaluate DF (Fig. 1), LACI-v/m, and LACI-av. Venous blood samples were obtained for NT-proBNP measurement. Athletes were examined during the competitive season under standardized resting conditions and were instructed to avoid intense exercise for at least 24 hours before testing. Results A total of 387 healthy elite athletes, with a mean age of 30±7 years, 44% women were included. The cohort demonstrated mildly increased indexed left atrial end-systolic volume (LAESVi: 36±9 mL/m²), Early diastolic relaxation velocity was preserved (e′: 0.16±0.03 m/s) and left ventricular filling pressures were normal (E/e′ ratio: 5±1). Binary logistic regression demonstrated an association between E/e′ ratio and elevated NT-proBNP levels (OR =1.504, 95% CI: 1.056–2.143; p = 0.024). Restricted cubic spline analysis revealed a positive nonlinear relationship between E/e′ and NT-proBNP, with a progressive rise in NT-proBNP observed when E/e′ exceeded 6 (Fig. 2). A limited positive association was also observed between LAESVi and NT-proBNP at higher atrial volume ranges (Fig 2). Compared with reported reference values, athletes demonstrated increased LACI-v/m and LACI-av. When stratified by reference value, no statistically significant associations were observed between LACI-v/m and DF metrics, including E/e′ ratio (OR = 0.927, 95% CI: 0.542–1.586; p = 0.783). Similarly, no statistically significant association was found between LACI-v/m and DF metrics. Conclusions DF is supranormal in elite athletes and shows only modest association with NT-proBNP, suggesting biomarker elevations are not driven by overt dysfunction. Conventional cutoff values for LACI-v/m and LACI-av are not associated with DF parameters, indicating that standard thresholds may not apply to athletes. Athlete-specific reference ranges and longitudinal studies are needed to avoid misclassification and clarify future cardiovascular risk.