Transseptal Transcatheter Mitral Valve-in-Valve Ups Survival in High-Risk Patients

SAN FRANCISCO, CA—Transcatheter mitral valve-in-valve procedures, especially those done via transseptal access, are associated with low mortality and adverse event rates as well as quality-of-life improvements through 1 year in addition to a high rate of procedural technical success, according to real-world data from high-risk patients in the TVT Registry.

“Transcatheter mitral valve-in-valve is preferable to redo mitral surgery and should be the standard of care for patients with failed surgical prostheses who have favorable anatomy,” said Mayra Guerrero, MD (Mayo Clinic, Rochester, MN), who presented the findings today in a late breaking science session at TCT 2019.

She told TCTMD that over her 6 years of experience performing these procedures she has never once used transapical access and believes transseptal should be the default option. “From day one, I knew and I made the conscious decision that if we're going to do this, we're going to do this with transseptal access because I don't want anybody to be poking a hole in my left ventricle,” she said. “So . . . why would I want to do that to somebody else?”

TVT Registry Data

For the study, Guerrero and colleagues looked at data on 1,576 mitral valve-in-valve cases using the Sapien 3 TAVR valve (Edwards Lifesciences) captured from the Society of Thoracic Surgeons/American College of Cardiology TVT Registry between June 2015 and August 2019. Most procedures (84.1%) were performed with transseptal access, which increased in prevalence over the study period. Most baseline characteristics were the same regardless of access site with the exception of a lower incidence of A-fib and a higher incidence of prior CABG in the transapical arm. The mean STS score was 11 in the transseptal arm and 11.7 for patients treated transapically.

Those who received the procedure with transapical access had a lower fluoroscopy time (18.2 vs 37 minutes; P < 0.001) and were more likely to be converted to open surgery (2.5% vs 0.7%; P  = 0.03) compared with the transseptal access group, but there were no differences with regard to procedure time, valve sizes used, device embolization, and cardiac perforation.

Technical success, the primary safety endpoint, was numerically higher for those treated with transseptal access than for the transapical group (97.13% vs 94.58%; P = NS), but transseptal access showed a clear benefit for the primary efficacy endpoint of all-cause mortality at 1 year (15.8% vs 21.7%; HR 0.67; 95% CI 0.47-0.97).

There were no differences in the individual in-hospital endpoints of stroke, mitral valve reintervention, new pacemaker, periprocedural MI, or major vascular complications, but the transseptal access cohort benefitted in terms of cardiovascular death (1.8% vs 4.4%; P = 0.03), median length of stay (2 v 6 days; P < 0.001), and rate of discharge to home (82.5% vs 59.1%; P < 0.001).

The ratio of observed versus expected 30-day mortality based on STS score was low for both groups, but it was lower for transseptal (0.45) than for transapical access (0.69).

Similar improvements in quality of life, as measured by NYHA class and Kansas City Cardiomyopathy Questionnaire at both 30 days and 1 year, were observed for both access strategies.

On multivariate analysis, transseptal versus transapical access predicted 1-year survival (HR 0.58; 95% CI 0.37-0.9).

Surgeon Enthusiasm

Michael Mack, MD (Baylor Scott and White Heart Hospital, Plano, TX), commenting during a media briefing, was encouraged by these results. “I don’t think any surgeon is going to disagree with this: if we don't have to do another redo mitral valve operation, that's a good thing,” he said. “This is a very positive finding for us because if you look at most operations done in cardiac surgery, the 30-day mortality is between 1 to 3%. The mortality here is 11%, it’s one of the highest risk procedures we do in cardiac surgery. To have an alternative that cuts that 30-day mortality in half, down to 5%, is very much a positive.”

I don’t think any surgeon is going to disagree with this: if we don't have to do another redo mitral valve operation, that's a good thing. Michael Mack

Mack said his only concern at this point relates to the long-term durability of transcatheter valves in the mitral position. “The mortality is 16% at 1 year. Is that an early signal that there is something going on?” Mack commented. However, “I think that this clearly answers that this is the preferred therapy whether you come into a surgeon or cardiologist with this problem.”

Similarly, Pinak Shah, MD (Brigham and Women’s Hospital, Boston, MA), noted that the durability issue is “the elephant in the room” but said these findings are “exactly what I would have expected” based on his experience with the procedure. “Right now the procedure is approved for high risk patients, [but] we are seeing already patients who are low and intermediate risk. It still remains questionable as to whether or not this is going to be the right therapy. Unlike TAVR, where we have very good long-term data, we don’t have as much long-term data for this,” he explained.

“In order for me to be worried about the future, I need to be alive first,” Guerrero responded. “The mortality in all the registries . . . is in the double digits. Is there such a thing as low-risk redo mitral valve? I don’t know.”

Ajay Kirtane, MD (NewYork-Presbyterian/Columbia University Irving Medical Center, New York, NY), who moderated the press conference, said that “there are hints of data on transapical in general, and I think the key thing is most of it is converging on the less invasive you can get, probably the better.”

Temporal Trends in Access

Also commenting during the media briefing, Robert Bonow, MD (Northwestern University Feinberg School of Medicine, Chicago, IL), said he’s “fully on board” regarding a transcatheter approach to failed mitral bioprostheses. “My question is the temporal relationship between transapical and transseptal in this population from the registry,” he said. “The field is moving to transseptal so I'm assuming that most of the transapical procedures were done at an earlier date, so some of this could be a temporal trend toward more experience?”

Guerrero agreed, acknowledging that early operators were likely adapting their TAVR approach to this procedure. “Operators were more comfortable with the transapical access from their TAVR experience,” she told TCTMD. “All they had to do was just flip the valve backwards, change the angle a little bit, and then put in the mitral valve.”

But from the patient’s perspective, there is a “clear advantage” to the less-invasive option, even though some operators view transapical access as easier to perform, she stressed. “Transseptal may require a different set of skills. . . . It's one of those things you just have to do it and do it. As an operator, I don't see a reason to do transapical unless transseptal cannot be done for a real anatomical reason—for example, a septum that is heavily calcified that cannot be crossed or a patch that cannot be crossed. But we have crossed patches from patients who have prior surgeries. Yes, it's a little challenging and requires a little more work, but it can be done.”

Looking forward, Guerrero said that if transcatheter mitral valve-in-valve procedures are going to become the new standard of care, then surgeons planning first-time mitral valve surgeries today should begin thinking about using surgical bioprostheses that will be more “friendly” to a potential transcatheter procedure down the line.

“There are some surgical prostheses that cannot be further expanded and they can lead to higher gradients and some are not visible under fluoroscopy so the ones that are easily visible makes the procedure a lot easier to do,” she said. “Perhaps now that should be part of the informed consent process and discussion with the patient if a surgical bioprosthesis is being chosen. . . . Maybe pick one that's going to make it easier 10 years from now.”

Asked about this idea during the media briefing, cardiothoracic surgeon Vinay Badhwar, MD (West Virginia University, Morgantown), said, “I don't think we're there quite yet, but obviously that’s the direction people are thinking.”

Badhwar emphasized that these study results apply to high-risk patients. “The veracity of that conclusion—that [transcatheter mitral valve-in-valve] is good for every redo surgery probably needs to be tempered a little bit because this is for high-risk patients, of course,” he said. “I don’t want to do a high-risk redo mitral [surgery]. However, for low-risk patients or for patients that have slightly different anatomic criteria . . . there might be some [considerations] that we might need to be thinking about before treating.”