Abstract 4291: Implantation of the Medtronic Melody Transcatheter Pulmonary Valve for Dysfunctional Right Ventricular Outflow Conduits: Clinical Results of Initial 99 Patients in the U.S. Investigational Device Exemption Trial
Background: Enrollment into the prospective, non-randomized, 5-center, U.S. investigational device exemption trial for implantation of the Melody transcatheter pulmonary valve (TPV) for right ventricular outflow tract (RVOT) dysfunction began in 1/2007. We report procedural outcomes and 6 month to one year follow-up (FU) of the first 99 pts enrolled.
Methods: Outcome measures of safety and procedural success were evaluated at implant by cardiac catheterization (cath) and echocardiography (echo). Effectiveness at 6 –12 months was evaluated clinically by NYHA classification and cardiopulmonary exercise testing (CPET) and by evaluating relief of RVOT stenosis, pulmonary regurgitation (PR), indexed RV volume (RVEDVI) and evidence of pulmonary embolism (PE) using echo, MRI and CT. Stent integrity and fractures (FX) were evaluated by CXR and fluoroscopy.
Results: 99 pts (mean age 20.6±9.2 yrs) underwent cath for possible TPV from 1/07–12/08. Most common diagnosis was tetralogy of Fallot (53%). Primary indication for TPV was stenosis (21%), PR (59%), and mixed disease (20%). NYHA class was ≥II in 83%. 90 pts underwent TPV implant. 9 pts were excluded (risk of coronary compression in 4, hemodynamic/anatomic factors in 5). Immediate cath results showed the RV-PA gradient decreased from 35±16 to 14±7 mmHg (p<0.001) and all but 1 pt had ≤trivial PR. Four complications occurred including coronary dissection in one leading to death and homograft rupture in one managed surgically. In FU, 75% were NYHA I with none > NYHA II. CPET showed a decrease in VE/VCO2 at anaerobic threshold. Mean RVOT gradient was 20±8 at 6 mo and 22±10 mmHg at 1 yr with no increase compared to immediate post-TPV values. PR was ≤ trivial in 97% at 1yr. RVEDVI decreased (127±48 pre-TPV vs. 102±39 ml/m2 at 6 mo, p<0.001). No pt had evidence of PE. Freedom from stent FX was 89% at 6 mo and 77% at 1 yr. 6/16 with stent FX underwent cath reintervention for stenosis (5 repeat TPV, 1 angioplasty). Freedom from surgical reintervention was 99% at 1 year.
Conclusion: TPV implantation for RVOT conduit dysfunction is safe and effective up to 1 year with low TPV-related morbidity. Recurrent obstruction due to stent FX can be managed at cath with repeat TPV implantation.