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A new era is arriving for treatment of aortic stenosis. With the updated National Coverage Determination (NCD) and evidence from showing better outcomes for low-risk patients with transcatheter aortic valve replacement (TAVR) compared to surgical replacement, TAVR will be the way for most patients going forward.

Updated society guidelines as well as FDA approval for TAVR in low-risk patients are expected soon. The use of TAVR in patients with aortic stenosis who were at high and intermediate risk for complications in surgery was approved in 2012 and 2016, respectively. With the coverage decision and a green light for low-risk patients, the floodgates will soon open as more hospitals, especially smaller community hospitals, begin to perform TAVR. It means more patients will have accesses to a real choice based on medical factors, not just whether they have access to one of a limited number of high-volume facilities that have been eligible to do TAVR.

Beat the Learning Curve

While this is amazing news that will provide better options for patients, we have some concerns about the rapid growth of TAVR. As 200 new centers are expected to open in the next 18 months, TAVR teams will find themselves back where we were in 2011 in terms of experience with the procedure.

It takes 50 to 100 procedures for a surgeon and interventional cardiologist to get over the learning curve so they can readily identify and avoid potential complications. Patients shouldn't suffer because they're in a center new to TAVR while an established center is potentially just 50 to 100 miles away.

TAVR safety has steadily improved through three generations of valves, multiple clinical trials, national registry surveillance, and nearly a decade of experience. The hardware has evolved to address previously identified complications. For example, catheters have gotten smaller, and valves themselves have improved with each iteration. In addition, teams of surgeons, interventional cardiologists, and general cardiologists have gained experience and learned how to collaborate and plan for the best outcomes.

For the Banner -- University Medicine Heart Institute team in Phoenix, planning is 90% of the procedure. One valuable part of the planning process is that CT scans are used routinely now. In the past, we used ultrasound for choosing valve sizes. This change alone has helped identify and prevent major complications, like valve embolizations, and has lowered the incidence of para-valvular leaks.

Seasoned Teams Supporting New Centers

Better access to TAVR should not mean poorer quality. A strategy for better access and sustained quality is pairing new centers with sister organizations. Rather than going back to 2011 and reinventing an effective process, new centers can partner with sister organizations to consult and refer difficult cases to the higher-volume center. Banner has a hub-and-spoke model with its sister organizations, where our experienced team at the flagship hospital helps and supports teams at community hospitals and receive their most difficult cases.

The NCD kept some volume minimums, which have served as a surrogate for quality in evaluating TAVR centers; and the Centers for Medicare & Medicaid Services (CMS) is encouraging the development of outcome measures to be tracked through required participation in the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy (TVT) Registry. Hard outcome measures include mortality, kidney failure, stroke, transient ischemic attack, vascular complications, pacemaker implantation rate, and quality of life at 1 year. This is a positive development, because high volume indicates experience but does not always translate to quality. Some high-volume centers have not achieved good outcomes, while some low-volume centers are getting good results.

Collaboration Is Key

As the use of TAVR grows, strong collaboration between the surgeon, the interventional cardiologist, and the general cardiologist is more important than ever. While TAVR has many advantages over surgical valve replacement, the surgical approach is not going away.

For a small portion of patients, surgery is still the best choice. Certain anatomy is likely to lead to complications with TAVR, including when blood vessels in the groin are too small, when coronary height is too low, or when congenital abnormalities are found in the aortic valve. Surgery is also a better option when opening the chest is required for another reason, such as a concomitant blockage, mitral valve replacement is needed in addition to the aortic valve, or when work is required on the aorta.

It takes a well-developed team pulling together in the best interest of the patient to individualize the approach to aortic valve replacement, considering patient history and available imaging, while pushing aside motivations related to ego, money, or even uninformed patient preferences. Sometimes a well-functioning team will determine if a third choice is in the patient's best interest -- to do nothing when it would be futile because the patient is likely to die from another condition.

The Second Surgeon Question

The NCD lifts the requirement for approval for TAVR from two surgeons. For a well-functioning heart team that is truly working together to choose the best option for each patient, this is a welcome change.

While the third opinion from a second surgeon provides some protection, the requirement could be a burden. One additional step to the pre-procedure process can be onerous for patients, delaying TAVR by a week or more to schedule with and visit two surgeons, each with limited office hours. In most cases, this delay is not an issue in terms of health and outcomes, but it adds to the stress for patients and family members already worried about a serious diagnosis.

Opening TAVR to low-risk patients reduces the need for a second opinion, but there is still room for abuse. Since surgeons depend on the cardiologist for referrals, a surgeon may feel pressure to approve TAVR. It is much harder to get two surgeons to agree if it's not the best course. A well-functioning team recognizes that there are still cases where surgery is the best option and guides the patient to the best choice.

Ashish Pershad, MD, is an interventional cardiologist practicing at Banner -- University Medicine Heart Institute in Phoenix. He also serves as program director for the Interventional Fellowship Program at Arizona College of Medicine.

H. Kenith Fang, MD, is a transcatheter valve therapy specialist with a special interest in minimally-invasive heart and lung surgeries. He is Chief of Cardiothoracic Surgery at the Banner -- University Medicine Heart Institute in Phoenix and a clinical associate professor of surgery at the University of Arizona College of Medicine Phoenix.

Mark Tasset, MD, is a cardiothoracic surgeon at Banner -- University Medicine Heart Institute in Phoenix, one of the centers that participated in the PARTNER 3 clinical trial.

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