With transcatheter valve-in-valve implantation emerging as a novel treatment for high-risk patients whose existing bioprostheses have deteriorated, a team of investigators at University Heart Center in Hamburg, Germany, has found that the procedure can be done successfully in four different anatomic positions with a variety of bioprostheses.
The findings from the single-center study were published in the December issue of the Journal of Thoracic and Cardiovascular Surgery. (J Thorac Cardiovasc Surg. 2015;150:1557-67). They retrospectively analyzed results of 75 patients who had transcatheter valve-in-valve (ViV) replacement at their institution from 2008 to 2014.
“ViV can be performed in all anatomic positions with acceptable hemodynamic and clinical outcome in high-risk patients,” wrote Dr. Lenard Conradi and coauthors. “Increasing importance of ViV can be anticipated considering growing use of surgical bioprostheses.”
Replacement of biological valves is becoming more common. For surgical aortic valve replacement (SAVR), biological procedures have largely replaced mechanical valve implantation, comprising 87% of all such procedures by 2014, according to data from the German Society for Thoracic and Cardiovascular Surgery (Thorac Cardiovasc Surg. 2014;62:380-92). “Therefore, increasing caseload of patients with deteriorated bioprostheses can be expected,” wrote Dr. Conradi and coauthors.
The four anatomic positions in which the investigators performed the procedures and their share of cases are: aortic (54 patients/72%), mitral (17/22.7%), and tricuspid and pulmonary positions (2/2.7% each). The average interval between the index procedure and ViV was 9 years, with a deviation of nearly 5 years among all procedures. Dr. Conradi and coinvestigators said their study focused on technical aspects of ViV procedures from each position to provide guidance for surgeons.
Overall, the study authors performed ViV successfully in 97.3% of patients, with two patients requiring sequential transcatheter heart valve implantation for initial malpositioning. Thirty-day mortality was 8%, which “ranged lower” than expected when compared to standard preoperative risk stratification, they wrote. Mortality was at 5.6% in the aortic group and 17.6% in the mitral group.
That none of the currently available surgical bioprostheses or transcatheter heart valves (THV) were designed for later ViV procedures in deteriorated bioprostheses – although the CoreValve and Sapein THV have approvals for the indication – “may explain some of the apparent shortcomings of ViV therapy,” the researchers wrote.
The most significant challenge of ViV therapy is dealing with elevated residual gradients, which positioning can influence, according to the study findings. “This is not so much an issue for mitral, tricuspid, or pulmonary positions since surgical bioprostheses implanted in these positions are usually of sufficient size to accommodate the THV,” the researchers noted. “However, in the aortic position, more severe spatial restrictions may apply.”
They cited other reports that described a reverse relationship between size of the bioprosthetic and resulting transvalvular gradient after ViV (JACC Cardiovasc Interv. 2011;4:1218-27; JAMA 2014;312:162-70).
To reduce gradients, the investigators used post-ballooning after aortic ViV with a self-expandable THV in 16 cases, succeeding in 12. “Likely, further THV expansion with active compression of soft leaflet and/or pannus tissue and tighter apposition of THV against the frames of surgical bioprostheses contributed to this desired effect,” wrote the researchers. Patient-prosthesis mismatch probably explained the four cases in which gradients could not be further reduced, they noted.
They issued one “word of caution” regarding aortic ViV in small-sized surgical bioprostheses: “Elevated postprocedural gradients have to be expected and must be weighed against expected benefits and against risk of repeat open heart surgery.”
The six transcatheter heart valves the investigators used were Edwards Sapien (XT)/Sapien3 (52%, 39/75); Medtronic CoreValve/CoreValveEvolut (34.7%, 26); St. Jude Portico and Boston Scientific Lotus (4%, three each); and JenaValve and Medtronic Engager (2.7%, two each). The study also looked at different access routes: transapical in 53.3% (40), transfemoral (transarterial or transvenous) in 42.7% (32), transaortic in 2.7% (2), and transjugular in 1.3% (1).
Dr. Conradi and coauthors Dr. Moritz Seiffert, Dr. Ulrich Schaefer, and Dr. Hendrik Treede disclosed ties with Edwards Lifesciences, JenaValve Technology, Medtronic, Symetis, and St. Jude Medical. Four other coauthors reported no disclosures.