June 28, 2019
6 min read

STS News, Summer 2019 — With trends emerging and new data available, the time may have finally come to designate transcatheter aortic valve replacement (TAVR) as the preferred treatment for aortic stenosis in most patients.

Since the first valve implantation in 2002, TAVR’s feasibility and effectiveness have consistently been substantiated by an accumulation of rigorous, evidence-based clinical experience. Simplification of the technique and improvements in valve design and delivery systems also have helped advance this rapidly evolving technology.

TAVR procedure

Data from the STS/American College of Cardiology (ACC) Transcatheter Valve Therapy (TVT) Registry™ confirm that the number of TAVR procedures performed annually in the US is more than double the number of isolated surgical AVR procedures performed to treat aortic stenosis. In 2012, when the technology was first approved by the US Food and Drug Administration (FDA), fewer than 5,000 TAVR procedures were performed. Six years later, in 2018, more than 59,200 TAVR procedures were completed in the US, while an estimated 25,274 isolated SAVRs were performed.

This is an “amazing and dramatic development,” according to Joseph E. Bavaria, MD, chair of the STS/ACC TVT Registry Steering Committee. At Penn Medicine in Philadelphia, where Dr. Bavaria is co-director of the Transcatheter Valve Program, between 400 and 500 TAVR procedures are performed each year.

TAVR Could Benefit Low-Risk Patients

First reserved only for inoperable patients or those at high surgical risk, TAVR has since expanded to intermediate-risk patients. Next in line for TAVR are patients who are at lower risk for surgery, explained Dr. Bavaria. At the most recent ACC annual meeting, researchers presented two randomized TAVR trials—PARTNER 3 and EVOLUT—that confirmed the benefits of TAVR in the lowest-risk patients to date and are expected to pave the way for a new low-risk indication for TAVR technology.

“I anticipate that TAVR will be FDA approved for low-risk patients, and this will be an important advance as it will change the way aortic valve replacement is performed in 70% of all patients with aortic stenosis,” said Dr. Bavaria.

In the PARTNER 3 study, researchers investigated the outcomes of 1,000 patients across 71 hospitals—half underwent traditional open heart surgery and the other half received TAVR. The data indicated a 46% reduction in death, stroke, and rehospitalization at 1 year for the TAVR group. In addition, postoperative or new-onset atrial fibrillation was reported in only 5% of TAVR patients, compared to approximately 40% of SAVR patients. It is important to note that the trial demonstrated outstanding results for open heart surgery, as well.

“It is important that quality remains robust.”

Joseph E. Bavaria, MD

The EVOLUT study also supported TAVR as a safe alternative to traditional surgery. This research, which included 1,403 patients who randomly were assigned to undergo either TAVR (n=725) or SAVR (n=678), demonstrated that TAVR, when compared to open heart surgery for valve replacements, had a similar rate of disabling stroke or death at 2 years (5.3% versus 6.7%, respectively).

Paired with the results of the PARTNER 3 trial, the EVOLUT findings suggest that low-risk patients do as well and maybe even better with TAVR than with SAVR after 2 years. Both the PARTNER 3 and EVOLUT studies were published in the New England Journal of Medicine (NEJM).

Also important to shaping the future of TAVR is the TVT Registry. Often referred to as a “national treasure,” the Registry is an essential component in TAVR data collection. The list of published research using data from the TVT Registry continues to grow; very importantly, the research has provided essential information on new therapies and identified outcomes in groups of patients not treated in randomized clinical trials (such as those with bicuspid aortic valves).

“One wonderful thing about the TVT Registry is that it includes all TAVR cases throughout the entire United States,” said Richard J. Shemin, MD, chief of cardiac surgery and the Robert and Kelly Day Professor of Surgery at UCLA Health and the David Geffen School of Medicine. “It’s real-world experience that continues to evolve and will help provide outcomes data as the patient populations and indications change. In addition, the data will allow hospitals and TAVR teams to compare themselves to other sites, ensuring high-quality results and appropriate indications for the procedure. I think this gives a lot of confidence to the people who will suffer from aortic valve disease and eventually need a TAVR.”

The Value of Volume

Included in the Registry are approximately 610 participating TAVR sites, with 130 added just in the past 2 years. Dr. Bavaria explained that experts expect an increase to more than 850 sites within a few years. This growth is noteworthy, especially since the volume-outcome relationship debate is ongoing and was a hot topic considered by the Centers for Medicare & Medicaid Services (CMS) as it finalized a new TAVR national coverage determination (NCD). For the latest on the TAVR NCD, see page 15.

“TAVR will be the mainstay treatment for aortic stenosis. Period.”

Joseph E. Bavaria, MD

“With too many centers in the market, you work against the volume-outcome relationship, meaning that as cases get diluted over a lot of centers, each center does less TAVR volume,” said S. Chris Malaisrie, MD, co-director of the Bicuspid Aortic Valve Clinic and Thoracic Aortic Surgery Program at Northwestern Medicine in Chicago. “It’s been shown that the less you do, the worse the outcomes; the more you do, the better the outcomes.”

A recent study published in NEJM supported a volume-outcome relationship. Dr. Bavaria and colleagues analyzed data from the TVT Registry, which included 113,662 TAVR procedures performed at 555 hospitals by 2,960 operators from 2015 to 2017. The investigators observed an inverse volume-mortality association, with mortality at 30 days higher and more variable at hospitals with a low procedural volume than at hospitals with higher volumes.

The new NCD relaxes volume requirements, especially for hospitals looking to start a TAVR program. At the same time, CMS is trying to find the right balance between ensuring quality of care and maintaining sufficient access to TAVR. Dr. Bavaria explained that STS and ACC will work with CMS to develop “proper and sophisticated” metrics that will help guide the transition from a pure volume metric to an outcomes metric. This will help centers better determine areas of deficiency and hone in on specific outcomes measures that may be difficult to identify in day-to-day practice.

“We want to help ensure, through the TVT Registry and with these new metrics, that low-volume sites are performing quality work. We also want to identify any sites—low or high volume—that are performing work that is below standard,” said Dr. Bavaria. “It is important that quality remains robust.”

Future of CT Surgery

With more and more centers offering TAVR and an increased number of patients opting for this procedure over open heart surgery, what does the future of heart surgery look like? Dr. Malaisrie explained that surgeons will have to adopt a new skillset to include interventional and catheter-based procedures. In addition, the expansion of TAVR will affect how the next generation of cardiac surgeons are trained.

Dr. Bavaria agreed. “If you’re a cardiothoracic surgeon and you’re not involved with TAVR, your aortic valve treatment operations are going to decline. TAVR will be the mainstay treatment for aortic stenosis. Period.”