Transcatheter Heart Valves for Failing Bioprostheses

Transcatheter aortic valve implantation (TAVI) is emerging as an alternative to conventional surgical aortic valve replacement (AVR) in high-risk patients with severe symptomatic aortic stenosis (AS).1,2 Since the first-in-man procedure in 2002,3 TAVI has been rapidly adopted in Europe and Canada, and, to date, more than 30 000 procedures have been performed worldwide. TAVI early and medium-term results have been promising.3–5 In the first prospective, multicenter, randomized, controlled clinical trial in the United States (PARTNER), safety and effectiveness of TAVI was evaluated in a stratified population of inoperable and high-risk patients with severe symptomatic AS.6,7 Superiority of TAVI over medical therapy, including balloon aortic valvuloplasty, has been proven in inoperable patients in whom TAVI significantly improved survival and reduced cardiac symptoms.6 Furthermore, in high-risk surgical cohorts, TAVI demonstrated noninferiority to gold-standard surgical AVR in which all-cause mortality was similar at 1 year.7 However, in both inoperable and high-risk cohorts, TAVI was associated with higher incidence of major stroke and major vascular events.6,7While TAVI experience within native AS rapidly progresses, TAVI offers an attractive option for patients with failing bioprostheses (valve-in-valve concept). Over time, bioprostheses have been preferentially used over mechanical valves for valve replacement because of favorable clinical results, patient age, and preference—outperforming mechanical valves in market share.8 As life expectancy increases, degeneration of previously implanted bioprostheses will inevitably become more common, requiring reoperative valve replacement. Reoperation in patients with degenerated bioprostheses carries an operative mortality risk ranging from 1.5% to 23%, depending on patient age, sex, preoperative New York Heart Association (NYHA) class, left ventricular dysfunction, number of previous operations, urgency of operation, and technical difficulties caused by adhesions.9 In high-risk surgical patients who are candidates for reoperative valve replacement, TAVI …