309 Is it still justifiable to treat right outflow track obstruction by bare metal stenting?

Abstract

Right ventricular outflow track obstruction is an increasing concern in adult with congenital heart disease. Until recently, bare metal stenting (BMS) was the treatment of choice in this multi-operated population. Nethertheless pulmonary regurgitation resulting has not been studied in physiological condition yet. Furthermore, percutaneous pulmonary valve implantation (PPVI) is now possible. Our aim is to study changes in cardiac index occurring first after bare metal stenting and then after percutaneous valve implantation by magnetic resonance imaging performed under physiological condition. seven consecutive patients (median age 17 years) with severe outflow tract obstruction underwent bare metal stenting followed a few weeks later by a percutaneous valve implantation. Magnetic resonance imaging (MRI) with left cardiac index based and net anterograde pulmonary blood flow was performed under physiological condition, before and after BMS and after PPVI. BMS significantly reduced outflow track obstruction (maximal velocity 3,19 versus 2,3 cm/s; P < 0,05) with no significative change after PPVI (2,27 cm/s; P = 1). After BMS, a free pulmonary regurgitation occurred (15 versus 38%; P < 0,05) and pulmonary cardiac index decreased (3,2 versus 2,4 l/min/mΣ; P < 0,05). After PPVI, there was no pulmonary regurgitation left (2 +/-1,4%) and pulmonary blood flow showed a tendency to increase (2,4 versus 3,13 ml/min/mΣ; P = 0,07) while cardiac index significantly increased (2,7 versus 3,5 l/min/mΣ; P = 0,04) as well as left ventricular diastolic volume (70 versus 87 ml; P = 0,02). Under physiological condition, bare metal stenting has a deleterious effect on cardiac index based on pulmonary blood flow and confirmed by left cardiac index. PPVI improves cardiac output eliminating the free pulmonary regurgitation. Impact of PPVI on right ventricle remodelling should be established with longer studies.