Transcatheter mitral valve-in-valve replacement: A new ‘gold standard’?
Transcatheter valve-in-valve replacement for degenerated mitral bioprostheses was associated with similar 30-day and one-year mortality rates as redo surgical mitral valve replacement (SMVR) in a retrospective study, despite the former being performed in older, sicker patients.
Specifically, the one-year mortality rate was 11.3 percent in the transcatheter mitral valve-in-valve replacement (TMVR) group and 11.9 percent in the SMVR group. Researchers evaluated TMVR in 62 patients and SMVR in 59 individuals across three U.S. institutions. The procedures were performed between January 2007 and August 2017, although TMVR wasn’t offered until 2012.
The Society of Thoracic Surgeons’ average mortality prediction scores were 12.7 percent in TMVR patients and 8.7 percent in those undergoing the surgical intervention. Average age for patients in those groups was 74.9 and 63.7, respectively.
“Our major finding was that there was no difference in mortality at 30 days and at 1 year between the SMVR and TMVR patients despite the higher risk of TMVR patients,” the authors wrote in JACC: Cardiovascular Interventions, adding that outcomes would be expected to improve over time given the relative newness of the procedure.
“As the TMVR technique has evolved in terms of both planning and approach, the TMVR procedure has become more effective, less invasive, and safer. The transseptal technique has shortened the length of stay and achieved similar clinical and echocardiographic outcomes compared with those of SMVR,” wrote lead author Norihiko Kamioka, MD, with Emory University School of Medicine, and colleagues.
Echocardiographic measures of mean mitral valve pressure gradient and mitral regurgitation (MR) were similar between the two groups at one month. At one year, the grade of MR remained similar but average pressure gradient was higher in the TMVR group (7.2 mm Hg versus 5.5 mm Hg). However, the authors noted this difference “is likely not clinically important.”
They concluded their study—despite its small sample size and nonrandomized, retrospective design—indicates “TMVR may be a good alternative to SMVR in selected patients.”
In an accompanying editorial, two Canadian cardiologists said the small number of patients who were available for echocardiographic examination at one year—24 in the SMVR group and 22 in the TMVR group—limits the ability to make meaningful comparisons. In addition, TMVR data in general only have one year of follow-up, so it remains to be seen how durable the valves are for this purpose.
“Late TMVR prosthesis durability and hemodynamic performance are largely unknown and will need to be elucidated before TMVR can be widely adopted, especially among younger and low-risk surgical candidates with failed mitral bioprostheses,” wrote Josep Rodés-Cabau, MD, and Dimitri Kalavrouziotis, MD, both with the Quebec Heart and Lung Institute.
Despite these uncertainties, the editorialists believe TMVR could become a preferred therapy if additional studies support the conclusions of Kamioka and colleagues in a larger number of patients.
“Pending some important issues, such as the management of concomitant functional (tricuspid regurgitation) and valve durability, the confirmation of these findings would establish TMVR as the new gold standard for the management of surgical mitral bioprosthesis dysfunction,” Rodés-Cabau and Kalavrouziotis wrote.
Daniel joined TriMed’s Chicago editorial team in 2017 as a Cardiovascular Business writer. He previously worked as a writer for daily newspapers in North Dakota and Indiana.