Right ventricular outflow tract systolic function correlates with exercise capacity in patients with severe right ventricle dilatation after repair of tetralogy of Fallot

Abstract

OBJECTIVES: The relationship between exercise capacity and right ventricular (RV) components function in repaired tetralogy of Fallot patients with severely dilated right ventricles is poorly understood. The aim of this study was to characterize the exercise capacity and its relationship to RV global and components function in repaired tetralogy of Fallot patients with RV end-diastolic volume index >150 ml/m2, a currently accepted threshold for pulmonary valve replacement. METHODS: The medical records and results of cardiac magnetic resonance imaging and cardiopulmonary exercise testing of 25 consecutive eligible patients were reviewed. Twenty age-and gender-matched normal subjects were enrolled as cardiac magnetic resonance control. End-diastolic, end-systolic and stroke volumes, and ejection fraction (EF) were determined for the total RV and its components. RESULTS: Of the 25 patients, 44% maintained normal exercise capacity. RV outlet EF was higher (P = 0.02) and RV incisions smaller (P = 0.04) in patients with normal exercise capacity than those with subnormal exercise capacity. Predicted peak oxygen consumption correlated better with the RV outflow tract EF than with the EF of other components of the RV or the global EF (r = 0.59; P = 0.002). Multivariate analysis showed the RV outflow tract EF to be the only independent predictor of exercise capacity (β = 0.442; P = 0.02). CONCLUSIONS: Exercise capacity is preserved in some tetralogy of Fallot patients with severe RV dilatation. RV outflow tract EF is independently associated with exercise capacity in such patients, and could be a reliable determinant of intrinsic RV performance.