While surgical aortic valve replacement (SAVR) has long been the gold standard for treatment of aortic stenosis, transcatheter aortic valve replacement (TAVR) may well be the future, even for low-risk patients. The TAVR procedure is not only less invasive but, according to a review of recent literature, has been shown to be either noninferior or superior to SAVR.
“It’s no longer a controversy whether TAVR is safe,” said Lebron Cooper, MD, professor and chair in the Department of Anesthesiology at the University of Tennessee College of Medicine, in Memphis. “It’s definitely safe, and it’s approved for inoperable, extreme-risk, high-risk and intermediate-risk patients. Hopefully, we’ll find out next year whether it’s appropriate for low-risk patients, too.”
SAVR Versus TAVR
As Dr. Cooper explained at the 2016 annual meeting of the Society of Cardiovascular Anesthesiologists, SAVR is performed with an open heart procedure: The patient is induced under general anesthesia, placed on cardiopulmonary bypass, and the diseased aortic valve is replaced with either a mechanical or bioprosthetic valve.
With TAVR, on the other hand, the most common approach is transfemoral: A bioprosthetic valve is crimped and placed on a balloon stent and advanced in a retrograde fashion through the aorta.
When the aortic valve is reached, the balloon is inflated, and the replacement valve is expanded and deployed.
“A surgeon never has to open the patient’s chest; the patient never has to go on a heart–lung machine. And while still controversial, the procedure can now be done with MAC [monitored anesthesia care] instead of general anesthesia,” said Dr. Cooper, who also noted that this far less invasive procedure is most frequently performed in a catheterization or hybrid lab, not necessarily in an operating room, where anesthesiologists are more comfortable.
Rapid Adoption of the Procedure
While it’s still too early to declare TAVR the “best practice,” according to Dr. Cooper, it may well be the way of the future—and it is certainly not going away. First approved in the United States in 2011, TAVR has already been performed on more than 100,000 patients around the world.
In addition, clinical trials have shown TAVR to be not only a viable option, but perhaps a more suitable solution for inoperable patients compared with standard therapy (Lancet 2015;385:2485-2491).
It also has been proven to be an equivalent or superior alternative to SAVR in extreme or high-risk patients, Dr. Cooper added (see J Thorac Cardiovasc Surg 2016 Mar 12. pii: S0022-522300433-5; J Am Coll Cardiol 2015;66:1327-1334; J Am Coll Cardiol 2016;67:2565-2574).
Furthermore, recently published two-year results from a multicenter, randomized controlled trial of over 2,000 patients found transfemoral TAVR to be superior to SAVR in intermediate-risk patients, with a 1.8% reduction in all-cause mortality or stroke (N Engl J Med 2016;374:1609-1620).
Finally, one-year results from the PARTNER II study that included 1,077 patients at 51 centers in the United States and Canada showed that TAVR with the SAPIEN 3 valve (Edwards Lifesciences) is associated with lower mortality, fewer strokes and less aortic regurgitation in intermediate-risk patients, Dr. Cooper reported.
The propensity score analysis indicated a “significant superiority” using TAVR compared with SAVR, suggesting that TAVR might be the preferred treatment alternative in intermediate-risk patients (Lancet 2016;387:2218-2225).
“When we first started TAVR, it was with only the sickest, oldest and most inoperable patients, just to see if it was feasible,” Dr. Cooper explained.
“Now, it’s been approved for intermediate-risk patients, and they’re already starting low-risk trials this spring.”
Variation Across Hospitals
Although TAVR is superior—or at least noninferior—to SAVR, questions still remain. In 2012, 5,400 TAVR procedures were performed in the United States. Just one year later, that number rose to 10,599 and has since grown even higher. Despite the rapid adoption of the procedure, however, no long-term data exist for TAVR.
There’s also a discrepancy in survival outcomes depending on the hospital that performs the operation.
“Substantial variation exists across hospitals in mortality and readmission rates following TAVR, with patients treated at certain centers more than twice as likely to die within 30 days as those treated at the best-performing hospitals,” Dr. Cooper noted.
“While CMS [the Centers for Medicare & Medicaid Services] reports that there were 10,599 TAVRs performed in 336 hospitals in the United States in 2013—an average of only 32 TAVRs per center per year—we know that certain high-volume centers, such as Henry Ford, Brigham and Women’s, the Cleveland Clinic and a few others, perform close to 300 per year each. This suggests that most centers perform far fewer than 32 TAVRs per year,” Dr. Cooper said.
“The controversy is no longer whether these procedures should be done, but where. … The difference in mortality rate highlights the need to measure performance going forward and raises questions about the minimum number of procedures needed to maintain certification for a TAVR program,” Dr. Cooper concluded.