Is It Wise to Implant a SAPIEN Transcatheter Heart Valve in a Dysfunctional Right Ventricular Outflow Tract?

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• catheter intervention
• percutaneous pulmonary valve
• right ventricular outflow tract dysfunction

Is it wise for a Homo sapiens to implant a SAPIEN transcatheter heart valve (THV) (Edwards Lifesciences, Irvine, California) in a dysfunctional right ventricular outflow tract (RVOT)? Percutaneous pulmonary valve implantation (PPVI) for RVOT dysfunction, pioneered by Bonhoeffer et al. (1), is one of the most significant advances in the treatment of patients with congenital heart disease in the last 2 decades. PPVI preceded transcatheter aortic valve replacement, and the excellent results paved the way for transcatheter aortic valve replacement, which is now performed in much larger numbers worldwide.

Due to valve degeneration, even adult-sized, surgically implanted bioprostheses in the pulmonic position have limited longevity and need to be exchanged at median every 10 years (2). The initial intention of PPVI was to prolong the lifespan of a surgically implanted bioprosthesis by at least 2 years with the final goal to reduce the total number of open-heart surgeries in patients with congenital heart disease over their lifetime. The Melody valve (Medtronic, Minneapolis, Minnesota) received the CE mark for Canada and Europe in 2006 and Food and Drug Administration approval in 2010. The SAPIEN XT valve (Edwards Lifesciences) was approved by the Food and Drug Administration for percutaneous implantation in pulmonic position in the year 2016.

In this issue of JACC: Cardiovascular Interventions, Kenny et al. (3) present the 3-year follow-up results of patients treated with the SAPIEN THV in the pulmonic position (COMPASSION [Congenital Multicenter Trial of Pulmonic Valve Regurgitation Studying the SAPIEN Interventional THV] study). The COMPASSION study is a prospective, nonrandomized, multicenter investigational device exemption (IDE) study addressing the safety and efficacy of this treatment. Between 2008 and 2014, 22 patients were treated with a 26-mm SAPIEN THV and 47 with a 23-mm SAPIEN THV, respectively. The mean conduit gradient decreased significantly, as did the mean right ventricular systolic pressure. At 3 years follow-up, more than 90% of the patients had only mild or less pulmonary regurgitation. Freedom from mortality was 98%, freedom from reintervention was 94%, and freedom from infective endocarditis (IE) was 97%. There were no stent fractures. Although the number of treated patients is relatively small and the follow-up period is relatively short (total follow-up time was 192 patient years) the results are impressive and underscore the effectivity of this treatment mode.

Stent fractures, a known weakness of the Melody valve if used without pre-stenting (4), were absent in this study. However, in contrast to the early Melody experience, 91% of the current SAPIEN THV patients were pre-stented with a variety of bare-metal stents, which is known to reduce the number of potential valve–stent fractures (5,6). With adequate preparation of the valve landing zone, these fractures are not a clinically relevant problem any more. If implanted properly, the SAPIEN valves perform well at mid-term follow-up. Two early valve failures, 1 early stenosis and 1 early severe valve regurgitation, could be explained with a valve mismatch. The landing zone for the SAPIEN valve has to be circular and must be close to the nominal valve diameter. If this feature is not addressed properly, early valve dysfunction may result. In case of a nondistensible bioprosthesis as a landing zone, cracking of the valve ring of the bioprosthesis may be a possible solution to avoid an open-heart operation, if the valve ring is suited for this procedure (7).

All bioprosthetic valves predispose for IE. The annualized incidence of IE in this cohort for the SAPIEN THV was 1.04%, which is low. Among the exclusion criteria in the COMPASSION trial, however, the authors mention a history of endocarditis. This could have concentrated the study population to patients at lower risk for IE. A recently published report with longer follow-up time and significantly more patient years after Melody valve implantation reported an annualized IE incidence of 1.9% (8). In contrast to other authors (9), at present, we feel that more data are needed to decide whether there is a significant difference in the risk for IE after SAPIEN THV or Melody valve implantation. Not only the annualized IE rate would have to be taken into account, but for comparison of the IE risk, the indication for PPVI treatment is also important. In practice, mostly the larger SAPIEN valves (26 and 29 mm) are used in adults with large outflow tracts, mostly after transannular patch reconstruction, leaving the treated patients with very low residual systolic pressure gradients after PPVI. This is in contrast to severely stenotic RVOTs in small children with often degenerated conduits, where sometimes higher end-procedural systolic gradients in the RVOT have to be accepted and where mostly the Melody valve is used.

In contrast to the Melody valve, the SAPIEN XT valve is advanced unprotected through the tricuspid valve and into the final destination in the RVOT. It must be avoided that during valve advancement, the tricuspid valve cordae are trapped and that the valve is caught in the struts of a pre-stent. Severe tricuspid valve dysfunction has been reported recently as a complication after PPVI with the SAPIEN valve (10). With the excellent stability of the SAPIEN valve stent, it may be an interesting new approach to directly implant the valve in the RVOT without preceding preparation of the landing zone with stents (11).

Finally, is it wise to implant a SAPIEN valve into a dysfunctional RVOT? The answer is definitely yes, especially as in large RVOTs >26 mm, at present, the SAPIEN valve is the only possible transcatheter option. With slight overdilation, RVOTs up to 31 mm in diameter are amenable to PPVI with the SAPIEN valve (12). In RVOTs up to 24 mm in diameter, it is helpful for the interventionalist to have the choice between 2 excellent percutaneous valves.

• 2018 American College of Cardiology Foundation