Cardiac remodelling in male and female athletes: An MRI assessment of cardiac size and its impact on cardiorespiratory fitness

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Abstract Background Cardiac remodelling occurs in response to endurance training in elite athletes. Previous small studies have shown relationships between cardiac size and cardiorespiratory fitness (CRF) using echocardiography, but few studies have assessed the relationship on a larger scale with female athletes and cardiac MRI. Aim To examine the relationship between CRF and MRI measures of cardiac size and function in male and female endurance athletes. Methods 183 male and 64 female elite endurance athletes aged > 16 years underwent assessment of biventricular size and function using cardiac MRI and CRF (as measured by VO2peak). The association between biventricular size, function and VO2peak was assessed using univariate linear regression and multivariate regression adjusting for age, BMI and systolic blood pressure. Results There was a strong correlation between VO2peak and LVEDV and RVEDV in both male and female athletes (females r = 0.81 and r = 0.82 respectively, males r = 0.76 and 0.67, p < 0.001). There was no significant correlation between VO2peak and LV or RV EF in female athletes, and there was a weak association in males (LVEF r= 0.15, p=0.04, RVEF r = 0.27, p< 0.001). On multivariate analysis, LVEDV and LV mass were independent predictors in males and explained 78% of the variance in VO2peak (b = 0.41 and 0.18 respectively, p= < 0.001) and only LVEDV was an independent predictor in females explaining 64% of VO2peak variance (b =0.67, p < 0.001). Conclusion CRF as measured by VO2peak is determined by cardiac size as opposed to function in both male and female elite endurance athletes. This study is the largest assessment of endurance athletes with cardiac MRI and emphasises the role of cardiac volumes in predicting exercise capacity in the population.