Systolic Function of Right Ventricular Outflow Tract is a Better Predictor to Exercise Performance After Pulmonary Valve Replacement in Tetralogy of Fallot.

Debate on the proper timing of pulmonary valve replacement (PVR) after repair of tetralogy of Fallot is still continuing. We aim to clarify how the different components of right ventricle (RV) changed with relieved volume overload in the remodeling process after pulmonary valve replacement and gain a clear idea of the relationship between different right ventricle components function and exercise capacity after PVR in these patients. The medical records and results of cardiac magnetic resonance imaging and cardiopulmonary exercise testing of 25 consecutive eligible patients were reviewed. End-diastolic, end-systolic, and ejection fraction (EF) were determined for the total RV and its components before and after PVR. There was a marked increase in EF for the outlet after PVR (39.5 ± 11.4 vs. 45.6 ± 12.7, P = 0.04); however, EF and volume change for the other components showed no significant difference. Peak oxygen consumption (VO2 ) correlated better with the RV outflow tract EF than with the EF of other components of the RV or the global EF (r = 0.382, P = 0.018), and the time interval between initial repair and PVR showed a significant correlation with peak VO2 (r = -0.339, P = 0.037). Multivariate analysis showed the RV outflow tract EF to be the only independent predictor of exercise capacity (β = 0.479; P = 0.046). The systolic function of the RV outflow tract could be a reliable determinant of intrinsic RV performance in repaired TOF (rTOF) patients and a promising parameter for deciding timing of pulmonary valve replacement so as to achieve the best possible exercise capacity in repaired TOF patients.