Determinants of Exercise Capacity in Patients with Ebstein’s Anomaly: Is it all about the Left Ventricle?

Background: Ebstein’s anomaly (EA) has a variable morphological presentation causing a diminished exercise capacity. This study aims by a comprehensive evaluation with modern imaging techniques and clinical parameters identification of determinants of exercise capacity. Methods: Forty-five consecutive patients (median age 31 years, [6-69] underwent cardiac magnetic resonance imaging, transthoracic echocardiography, chest X-ray and ECG. A cardiopulmonary exercise test with determination of the maximum oxygen uptake (peak VO2) was performed in all patients. Results: Randomforest analyses revealed the following parameters as most important determinants of peak VO2 (order by decreasing relevance, in brackets linear correlation coefficient): early diastolic velocity of lateral mitral annulus (r 2 =0.22, p=0.02), left ventricular (LV) enddiastolic diameter (r 2 =0.11, p=0.03), ratio of early transmitral flow velocity to early diastolic velocity of the lateral mitral annulus (r 2 =0.12, p=0.024), LV stroke volume index (r 2 =0.09, p=0.044), oxygen saturation at peak exercise (r 2 =0.11, p=0.025), peak systolic velocity of mitral annulus (r 2 =0.09, p=0.05), right ventricular (RV) ejection fraction (r 2 =0.08, p=0.065), RV stroke volume index (r 2 =0.03, p=0.274), early diastolic velocity of tricuspid annulus (r 2 =0.11, p=0.056). Conclusions: EA causes a diminished LV preload leading to LV systolic and diastolic dysfunction responsible for a diminished exercise capacity. Atrial right to left shunting and RV function parameters play a less important role.