EComment. Transcatheter heart valve in the pulmonary position

Abstract

I read with great interest the paper by Abbas et al. regarding the best tissue valve substitute for pulmonary valve replacement in the setting of previous repair of tetralogy of Fallot [1]. They included in their search strategy stented bioprostheses and homografts as substitutes for pulmonary valve replacement. I would like to add a brief comment on the evolving role of transcatheter pulmonary valve implantation (TPVI) in such a subset of patients. Improvements in imaging, catheter technology, and stent design have made transcatheter replacement of the pulmonic valve a clinical reality. The Melody valve (Medtronic Inc, Minneapolis, MN, USA) was introduced in clinical practice in 2000 as a transcatheter alternative to pulmonary valve replacement for right ventricle-to-pulmonary artery outflow tract conduit dysfunction. The relative short lifespan of such conduits used in repairs of complicated congenital heart defects makes future surgical intervention unavoidable. TPVI offers an attractive alternative to surgery in patients with right outflow conduit dysfunction. Numerous studies have shown that the Melody valve is an accepted alternative to surgical pulmonary valve replacement in patient with right ventricular tract dysfunction with conduit less than 22 mm in diameter. Recently, Boudjemline et al. [2] found that patients with larger dysfunctional conduit with heamodynamically significant regurgitation can be treated successfully with the Melody valve. They implanted this valve in 13 patients with a previous history of surgically repaired tetralogy of Fallot using the Russian dolls technique and/or the pulmonary artery jailing technique, both pre-stenting techniques intended to prepare the large conduit to contain the Melody valve. One major drawback of the Melody valve is the high incidence of stent fracture leading to valve failure in more than 25% of cases [3]. The COMPASSION trial [4] is the first study to assess the safety and efficacy of the Sapien Pulmonic Transcatheter Heart Valve (THV) (Edwards Lifesciences LLC, Irvine, CA, USA) in this patient population. There were 36 patients enrolled in this prospective, non-randomized multicentre study. Pre-stenting of the conduit with a bare metal stent was accomplished in all cases; this provides a secure landing zone for the Sapien THV valve. The COMPASSION trial demonstrated that this valve yielded excellent short-term functionality up to 6 months after the implantation in the failure conduit (regurgitation with or without stenosis). There was no stent fracture in this cohort. Another advantage of the Sapien Pulmonic Valve is the availability in different and larger diameters than the Melody valve which is available only in one size (18 mm in diameter). TPVI is gaining increasing recognition as a less invasive alternative to surgical pulmonary valve replacement [5], however long-term results are lacking and further data are necessary to validate this interesting approach to right ventricular outflow tract dysfunction. Conflict of interest: none declared