Mitral Valve-in-Valve Replacement Upheld in 'Real-World' High-Surgical-Risk Patients

September 28, 2019

SAN FRANCISCO — Transcatheter mitral valve-in-valve (ViV) replacement has proven itself enough to be recommended to most patients with failing mitral bioprosthetic valves who are considered too high-risk for another surgery, researchers say.

In a "real-world" experience encompassing more than 1300 such patients undergoing the transcatheter ViV procedure via the transseptal approach, the 30-day mortality was only 5% — well under the predicted 11% risk of a surgical re-do procedure.

All patients received a SAPIEN 3 valve (Edwards Lifesciences), which was US Food and Drug Administration–approved for mitral ViV procedures in 2017. Those who received it transseptally compared to about 200 who were implanted via the transapical route had shorter procedures and hospitalizations and a significantly lower mortality over the next year.  

"I'm convinced that the data supports this as the standard of care for high-risk patients," rather than re-do mitral-valve surgery, Mayra Guerrero, MD, Mayo Clinic, Rochester, Minnesota, told theheart.org | Medscape Cardiology.

Guerrero has nearly always performed the transcatheter ViV procedure by the increasingly used transseptal approach, she said, although transapical may be preferred at some centers or in some cases.

"But for the first time now, we've found a significant difference between the two types of access," said Guerrero, who presented the registry experience here at Transcatheter Cardiovascular Therapeutics (TCT) Conference 2019.

The adjusted risk for death at 1 year was reduced by 42% (P = .014) for patients getting the procedure via the transseptal as opposed to the apical approach. However, symptom status and quality of life improved similarly and significantly in both groups of patients.

"I think the data that you've presented now has definitely established this as likely the procedure of choice for degenerated mitral bioprostheses," Charanjit S. Rihal, MD, also from the Mayo Clinic, Rochester, said as a panelist after Guerrero's presentation.

"This is an early experience. The median number of cases performed per center was four. But despite that, we see these outstanding results," said Rihal, who is a coauthor with Guerrero on the analysis.

But panelist Blase Carabello, MD, Brody School of Medicine, Greenville, North Carolina, who is not a coauthor, was just as enthused. "I think the results are fantastic."

Speaking at a media briefing on the study, surgeon Michael J. Mack, MD, Baylor Health Care System, Houston, said he doesn't think his colleagues will disagree about the study's findings.

"If we don't have to do another re-do mitral valve operation, that's a good thing. This is a very positive finding for us," he said.

"I think this clearly answers that this is the preferred therapy, whether you come to a surgeon or a cardiologist with the problem."

But, he asked, "A little bit of a concern is, what's the long-term durability?" He pointed out that all-cause mortality associated with the transseptal approach was nearly 16% at 1 year. It was almost 22% for patients getting the transapical procedure. Is that an "early signal" of longer-term valve compromise?

Indeed, unlike for transcatheter aortic valve replacement (TAVR), "for which we have very good long-term data, we don't have much long-term data for this," Pinak B. Shah, MD, Brigham and Women's Hospital, Boston, Massachusetts, said at the briefing.

"Right now the procedure is approved for high-risk patients, but we are already seeing patients who are low to intermediate risk," Shah said. "So I think it still remains questionable as to whether or not this is going to be the right therapy."

Also at the media briefing, Vinay Badhwar, MD, West Virginia University, Morgantown, seconded the note of caution. The conclusion of Guerrero presentation — that the ViV procedure should be the standard treatment for failed mitral bioprosthesis  — "probably needs to be tempered a little bit."

The study included only patients at high surgical risk, he observed, so it doesn't apply to lower-risk patients and probably not to every high-risk patient, he said. "There might be some anatomic selective criteria we might need to think about before treating everyone."

Its 1576 patients, who were seleted from the Society of Thoracic Surgeons/American College of Cardiology/Transcatheter Valve Therapy (STS/ACC/TVT) Registry and were not participating in clinical trials, underwent SAPIEN 3 transcatheter mitral ViV procedures at 271 centers from 2015 to 2019.

The 1326 and 203 patients who had the procedure via the transseptal and transapical approach, respectively, were similar at baseline with respect to most echocardiographic and clinical features, Guerrero said.

They didn't differ significantly in the study's primary safety endpoint, procedural technical success (including survival and successful device delivery, deployment, and positioning of the prosthesis; no bailout surgery or reintervention), met by 97% of transseptal and 94.5% of transapical patients.

But more transseptal patients survived to discharge, and their hospitalization was shorter.

Table 1. In-Hospital Outcomes of Mitral ViV Replacement by Route of Approach

Endpoints Transseptal (n = 1326) Transapical (n = 203) P Value
All-cause mortality (%) 3.6 6.4 .059
Cardiovascular death (%) 1.8 4.4 .03
Discharged home (%) 82.5 59.1 <.0001
Mean length of stay (d) 2 6 <.0001

 The transseptal group also had the advantage for the primary effectiveness endpoint, 1-year all-cause mortality, met by 15.8% of them and 21.7% of transapical patients (unadjusted P = .032); the hazard ratio was 0.58 (95% CI, 0.37 - 0.90) in multivariate analysis.

Table 2. 30-Day and 1-Year Outcomes of Mitral ViV Replacement by Route of Approach

Endpoints Transseptal (n = 1326) Transapical (n = 203) P Value
30 d      
  All-cause mortality (%) 5 8.1 .07
  Cardiovascular death (%) 2.1 5.1 .01
1 y      
  All-cause mortality (%) 15.8 21.7 .03
  Cardiovascular death (%) 3.7 5.7 .07

 

The two groups didn't differ significantly in rates of stroke at 30 days or 1 year. Nor did they differ significantly in rate of predischarge mitral-valve reintervention, which was well under 1% in both cases.

Both transseptal and transapical patients showed significant improvements in New York Heart Association functional class from baseline to 30 days and baseline to 1 year, with no significant differences between the groups at either interval. Improvements in Kansas City Cardiomyopathy Questionnaire quality-of-life scores followed exactly the same pattern.

Guerrero holds that transcatheter mitral ViV is "ready now" for replacement of failed mitral bioprosthesis in most patients regardless of surgical risk. "But we need support for that from clinical trials," she said. "If I have a patient who is not high-risk, I will strongly recommend and invite that patient to participate in one."

One possibility might be the ongoing PARTNER 3 Mitral Valve in Valve trial, for which Guerrero is one of three principal investigators. It is entering "non-high-risk patients," she said.

"We'll have to see the results of that trial for lower-risk patients. If the results are as good as these" from the current registry study, "then maybe it can be generalized to all types of surgical risk patients."

The registry study was supported by Edwards Lifesciences, from which Guerrero discloses receiving research support.

Transcatheter Cardiovascular Therapeutics (TCT) 2019 Conference. Late-Breaking Science 2. Presented September 27, 2019.

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