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Transcatheter Aortic-Valve Replacement

A Minimally Invasive Treatment for Patients with Severe Aortic Stenosis

The South Carolina Heart Valve Center  (HVC) at MUSC is the first center in South Carolina and among the first in the nation to perform transcatheter aortic-valve replacement (TAVR), a cutting- edge procedure for implanting a heart valve that does not require open heart surgery. Since approval by the US Food and Drug Administration in November 2011 for TAVR’s use in inoperable patients with severe aortic stenosis, MUSC’s HVC has performed 6 procedures, with many more TAVR candidates in the screening process.

Although surgical aortic valve replacement (AVR) remains the gold standard for treatment of severe aortic stenosis, TAVR makes treatment available to patients who would otherwise have gone untreated because they are not suitable candidates for surgery due to advanced age, frailty, or poor lung function (among other reasons). According to John S.  Ikonomidis, M.D., PhD, Chief of the Division of Cardiothoracic Surgery at MUSC, “It’s difficult, if you look across the medical community, to find a single procedure that modifies mortality in the way this procedure has in medically managed patients.”

Figure 1: RetroFlex 3 Delivery System: balloon-expanable valve technology. Image courtesy of Edwards Life Sciences (Irving, CA)
Figure 1: RetroFlex 3 Delivery System: balloon-expandable valve technology. Image courtesy of Edwards Life Sciences (Irving, CA)

Both TAVR and aortic valve replacement are treatments for severe aortic stenosis, or the obstruction of blood flow across the aortic valve because of calcific plaque. An estimated 2% to 9% of the elderly have aortic stenosis. Although aortic stenosis can gradually develop over years without symptoms, once symptomatic it takes a high toll in terms of mortality, higher even than a variety of cancers, including  lung cancer. Patients with severe aortic stenosis have a survival of only 50% at 2 years and 20% at 5 years if the condition is left untreated.

Instead of implanting a replacement heart valve during open heart surgery, TAVR involves collapsing a bovine heart valve mounted onto a stainless steel stent (the Edwards SAPIEN valve, Edwards Life Sciences, Irving, CA) tightly over a balloon (Figure 1), inserting it via a catheter into the ileofemoral artery and advancing it to the aortic valve. The procedure is performed twice: on the first pass, the balloon is expanded to open up the stenosis and on the second pass the Edward SAPIEN valve is deployed to keep the aortic valve open (Figure 2). The procedure can also be performed via an apical approach.

Until TAVR, those deemed unsuitable for surgical AVR had to face the grim survival statistics knowing that no treatments outside of medical management or aortic valvuloplasty (which provided only temporary symptom relief ) were open to them. It is estimated that 43% to 74% of patients with severe aortic stenosis never undergo surgery, either by choice or because it is contraindicated. Preliminary data from Cohort B of the PARTNER trial (NCT00530894) showing a 20% to 25% reduction in mortality at 2 years with TAVR versus medical management alone led to FDA approval of its use in inoperable patients.1 Patients also reported improved quality of life.

Figure 2. Aortic valve before (left) and after (right) TAVR. Image courtesy of Edwards Life Sciences (Irving, CA).
Figure 2. Aortic valve before (left) and after (right) TAVR. Image courtesy of Edwards Life Sciences (Irving, CA).

Since FDA approval, TAVR has been much in the news. On May 1, 2012, the Centers for Medicare & Medicaid Services agreed to reimburse patients for the procedure.2 On June 13, 2012, the FDA’s Circulatory Systems Devices Panel examining data from Cohort A of the PARTNER trial recommended approval of its use in high-risk surgical patients as well.3 The FDA has 100 days to decide whether to accept the recommendation.

Also in June 2012, MUSC’s HVC was approved as a clinical trial site for PARTNER 2 (NCT01314313), which will compare the safety and effectiveness of a smaller version of the SAPIEN (SAPIEN XT) transcatheter heart valve versus surgical valve replacement in patients with severe symptomatic aortic stenosis who are at intermediate surgical risk. The SAPIEN XT treats an annulus size range of 18 mm to 27 mm. MUSC’s HVC plans to enroll its first intermediate-risk patient in September of this year.

The multidisciplinary HVC at MUSC was created specifically to leverage these new types of valve technologies that dramatically alter a patient’s treatment options. Its depth of experience in both interventional cardiology and cardiac surgery, as well as its expertise in cardiac imaging and anesthesia, was key to its being approved by Edwards, the manufacturer of the Edwards SAPIEN heart valve, to implant the device. These devices can only be implanted once both an interventional cardiologist and a cardiac surgeon have assessed the patient (in part by preprocedural imaging ) and have agreed that he or she has a greater than 50% chance of dying or experiencing long-term complications from surgical aortic valve repair.

Possible complications of TAVR include stroke (some plaque may be dislodged as the valve is advanced through the vessel) and vascular  damage,  both  of  which  can  be  life-threatening.  Careful patient screening (ie, to ensure that the patient’s vessels are of sufficient size to allow the device to be implanted via a catheter) should help to minimize those risks. It is also hoped that the smaller size of the SAPIEN XT will help minimize these risks.

TAVR is most appropriate in patients with severe aortic stenosis who are not suitable candidates for surgery and who would stand to gain considerable quality of life as a result of the procedure. It offers a treatment option, increased survival and increased quality of life to a large pool of patients who would otherwise go untreated. If the FDA decides to follow the recommendation of the advisory panel and approve TAVR for high-risk patients, then by September MUSC’s HVC could be treating three distinct populations of patients with severe aortic stenosis: patients who are inoperable or at high surgical risk as part of FDA-approved standard of care and intermediate-risk surgical patients as part of the PARTNER 2 trial.

For a referral to the TAVR program, contact MEDULINE at 1-800-922-5250 or 843-792-2200 and ask to be connected to John S. Ikonomidis, M.D., PhD, Chief of the Division of Cardiothoracic Surgery at MUSC;  Daniel  H.  Steinberg,  M.D., the primary interventional cardiologist at the HVC involved in the TAVR program, or Suzanne Richardson, RN, the TAVR program coordinator.

References

1 Leon MB, Smith CR, Mack M, et al; for the PARTNER Trial Investigators. Transcatheter aortic-valve implantation for aortic stenosis in patients who cannot undergo surgery. N Engl J Med. 2010;363:1597-1607.

2 Centers for Medicare & Medicaid Services. Decision memo for transcatheter aortic valve replacement (TAVR) (CAG-00430N). Available at http://www.cms.gov/medicare-coverage-database/details/nca-decision-memo.aspx?NCAId=257&   ver=4&NcaName=Transcatheter+Aortic+Valve+Replacement+(TAVR)&bc=ACA   AAAAAIAAA&. Accessed June 25, 2012.

3 Yu D. FDA panel recommends clinical approval of SAPIEN TAVR device for high risk surgical aortic valve replacement candidates. The Advisory Board Company. Available at http://www.advisory.com/Research/Technology-Insights/The-Pipeline/2012/06/FDA-Panel-Recommends-Clinical-Approval-of-SAPIEN-Device-for-High-Risk-Valve-Surgery-Candidates. Accessed June 25, 2012.

This article originally appeared in the July/August 2012 issue of Progressnotes.

KEY POINTS

  • Patients with severe symptomatic aortic stenosis have a survival rate of only 50% at 2 years and 20% at 5 years if the condition is left untreated, poorer than that seen in many cancers.
  • Surgical aortic replacement is the gold standard for treating patients with severe symptomatic aortic stenosis, but many patients are not candidates for surgery because of advanced age, frailty, or poor lung function, among other factors.
  • Transcatheter aortic-valve replacement (TAVR), a procedure for implanting a heart valve (the Edwards SAPIEN valve; Edwards Life Sciences;Irving, CA) via a catheter that does not require open heart surgery, offers patients who are poor surgical candidates a much-needed treatment to prolong survival and improve quality of life.
  • In addition to being the first in the state to offer TAVR to inoperable patients, MUSC’s Heart Valve Center has also been chosen as a site for the PARTNER 2 trial of TAVR using a smaller Edwards heart valve in patients at intermediate surgical risk.
  • Already approved for inoperable patients, TAVR has been recommended for approval by a U.S. Food and Drug Administration (FDA) advisory panel for high-risk surgical patients as well; a final decision by the FDA is expected within 2-3 months.



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Drs. Steinberg and Ikonomidis discussing TAVR