Cardiac surgeons gaining procedural volume despite TAVR making up 84% of cases

A decade ago, when transcatheter aortic valve replacement (TAVR) was first cleared by the U.S. Food and Drug Administration (FDA), many expected TAVR would only be used in a small portion of patients, and surgeons had concerns about losing business. A decade on, the unexpected happened, and it turns out with TAVR, everyone is a winner, including the patient, interventional cardiologist, hospitals and the surgeons. 

Subsequent FDA TAVR pivotal clinical trials for new indications using the device in a declining order surgical risk patients found TAVR out-performed cardiac surgery in most areas at all levels. As a result, it is up to patients and their doctors to decide whether an open-heart surgical aortic valve replacement (SAVR) or minimally invasive procedure is best for their valve replacement. 

Not surprisingly, patients really liked the idea of minimally invasive transcatheter procedures, where they can be discharged the next day, rather undergoing open chest surgery on bypass with a much longer stay and rehabilitation. Today, TAVR procedures now make up more than 84% of aortic valve replacement procedures in the United States and surgical aortic valve replacement just 16%, explained Michael Mack, MD, chairman of the cardiovascular service line, Baylor, Scott, White Health, cardiac surgeon, and a key TAVR pioneer.

In 2021, there were 92,000 TAVR valves implanted in patients in the United States. Mack said the lines for procedural volumes between SAVR and TAVR crossed in 2018, as TAVR pushed beyond the 50% mark.

Ironically, the appeal of TAVR for referring physicians and patients has actually also helped increased surgical volumes, so cardiac surgeons are not looking for career changes because they have actually have not seen major procedure volume drops. At some centers, surgical volumes have actually increased.

How can this possibly be? Structural heart experts, surgeons and interventional cardiologists at the 2022 Transcatheter Valve Therapies (TVT) Structural Heart Summit said the attractiveness of TAVR as almost an out-patient procedure resulted in much larger numbers of referrals to heart centers in recent years. This included patients who previously would have waited until symptoms accelerated before seeking help coming in much earlier, people with fear of open heart surgery, younger patients and very sick elderly patients who might otherwise not have qualified for valve replacements. Many patients who came in are much better candidates for surgery, and often an educational discussion on why surgery was a better option for some patients led to surgery instead. 

All this greatly expanded the eligible patient pool from what cardiology had perviously thought was a fixed percentage of the population. There were patients who came out of the woodwork that had not been accounted for 10-20 years ago because many did not want surgery or were never referred because their symptoms were just not severe enough yet.

"We thought we operated on everyone with aortic stenosis. We did not realize as surgeons that many patients were screened out and never seen because their primary care physician did not feel the patients could survive surgery. TAVR has opened up treatment to a whole group of patients," Mack said. "There is a great sense that aortic valve disease is greatly under diagnosed, access to care issues and there are still two or three or four times greater number of patients that are not being treated that have severe aortic stenosis."

TAVR is attracting more patients than previously thought, but selection is still key

"Across the country, there are now more TAVR procedures performed than all aortic surgical procedures combined, and these numbers are never going to cross back," explained Michael Reardon, MD, professor of cardiothoracic surgery and Allison Family Distinguished chair of cardiovascular research at Houston Methodist DeBakey Heart and Vascular Center, and a TAVR pioneer. "At my institution, there are more TAVRs done than surgical valve replacements." 

Reardon contends aortic valve surgical volumes have gone down a little, but do not match a one-for-one rate of loss compared to the rapid growth of TAVR procedures. He agreed there are more patients overall with aortic disease coming into the cardiology departments than previously thought. 

"Surgery has gone down about 10[%], but it is not going down as much as TAVR is going up," Reardon explained. "The cases I am being referred for surgery are becoming more complex, and there is still plenty of surgery to do. TAVR is probably going to become the default for patients who have equipoise for outcomes, but there are always going to be people who will do better with surgery."

He said patients who will do better with SAVR include very young patients, people who need their ascending aorta replaced, also need their mitral valve repaired or suffer from endocarditis.

"There is no question that TAVR is going to become more prominent. That is what my patients are asking for. Almost nobody comes to my office and says 'doctor, will you please operate on me,'" Reason said. "The biggest problem I have is that I am being referred people who are 45 years old and the referring cardiologist is telling them they can have a TAVR. I have to explain to them why they are really not a candidate for TAVR, and they are still a better candidate for surgery."

He said the early data so far shows doing a TAVR first and years later doing a surgical replacement is more risky than the other way around, because patients do better with surgery the younger they are.

Mack said surgery is still considered the standard-of-care in younger patients because no synthetic valve can last as long as most younger patients will live. Surgical valves are considered more durable than TAVR valves, with 10-12 years of durability before they will start to degrade and need to be replaced. It was widely thought TAVR valves, with thinner leaflets and a frame that needed to be crimped into a catheter, would not have the same durability as a surgical valve. However, data continues to show TAVR valves do have good durability. Reardon presented the latest data on the Medtronic Core valve at the American College of Cardiology (ACC) 2022 meeting, showing the durability with TAVR was out-performing SAVR valves. 

"We tell surgical valve patients their valve should last out to 10 to 12 years," Mack said. "There does not yet seem to be a concerning signal in TAVR, but there are only a few patients who have been followed out to 8 years. There have been some surgical valves that looked great at 8 years, but then fell off."

Both Reardon and Mack said the jury is still out and more data is needed from longer TAVR followup periods. To answer the durability question, Mack said the ongoing low-risk patient TAVR trials will include followup out to 10 years.