Abstract 9555: Ventricular Geometric Characteristics and Functional Benefit of Mild Right Ventricular Outflow Tract Obstruction in Patients With Significant Pulmonary Regurgitation After Repair of Tetralogy of Fallot

Abstract

Aims: Right ventricular (RV) outflow tract obstruction (RVOTO) might protect the RV from adverse remodeling caused by pulmonary regurgitation (PR) in patients with repaired tetralogy of Fallot (rTOF), but the underlying mechanisms and influences on exercise tolerance remain unclear. This study sought to investigate the impacts from mild RVOTO on ventricular remodeling and exercise capacity in rTOF. Methods and results: 85 rTOF patients with a PR fraction ≥ 20% were assessed with cardiac magnetic resonance, cardiopulmonary exercise test, and echocardiography. Comparing to patients with isolated PR (a peak RVOT pressure gradient < 20 mmHg, n = 56), patients with combined PR and mild RVOTO (a peak RVOT pressure gradient 20-50 mmHg, n = 29) had smaller RV and RVOT dimension, better RV and left ventricular (LV) ejection fraction (EF), and superior exercise capacity. PR severity and RV mass/volume ratio were similar between these 2 groups. LVEF was influenced by RVEF only in patients with isolated PR. Smaller RVOT dimension was an independent geometric factor related to smaller RV dimension (P < 0.001) and better RVEF (P = 0.005) in multivariate analysis. Furthermore, mild RVOTO was independently associated with higher percentage of predicted peak oxygen consumption (P = 0.014) and predicted oxygen uptake efficiency slope (P = 0.005). Conclusion: Patients with combined PR and mild RVOTO had better RV remodeling and superior exercise capacity compared to those with isolated PR. Our findings confirm the benefits from mild residual RVOTO support a policy of conservative RVOTO relief at repair.