TAVR in 2012: Options for US patients with aortic stenosis

Issue: July 2012

ByPeter C. Block, MD

The Edwards Lifesciences Sapien valve for transcatheter aortic valve replacement, also known as TAVR, was approved by the FDA for use in patients with symptomatic aortic stenosis in November.

Since FDA approval, selected hospital sites in the United States have undergone training by Edwards Lifesciences to perform so-called “commercial” TAVR. The final number of sites in the United States that will perform commercial TAVR is unclear and will depend on patient volumes, ability to work within the “Heart Team” concept, experience/interest of operators and reimbursement.

With commercial availability of a TAVR device, expansion of TAVR use is occurring but limited.

Indications for ‘commercial use’

Restrictions on patient selection for commercial TAVR are limited. Readers are urged to review both the FDA-approved “Instructions for Use” and the National Coverage Decision (NCD) for reimbursement for TAVR. This commentary contains an abbreviated summary of these documents.

Peter C. Block

The Edwards Sapien transcatheter aortic valve is indicated for transfemoral delivery in patients with severe symptomatic native aortic valve stenosis who have been determined by a cardiac surgeon to be inoperable for open aortic valve replacement and in whom coexisting comorbidities would not preclude the expected benefit from correction of the aortic stenosis. The RetroFlex delivery system is indicated for the transfemoral delivery of the Edwards Sapien transcatheter aortic valve.

The CMS covers TAVR for patients with symptomatic aortic stenosis. Two cardiac surgeons must independently examine and determine that the patient is nonoperative or at extremely high operative risk.

For commercial use of TAVR, only the highest-risk patients are suitable, and these must be nonoperative candidates. Adequate iliofemoral access is crucial. For patients requiring a 26-mm Sapien TAVR, iliofemoral artery diameter must be minimally 8 mm if the arteries are free of calcium on CT, and 9 mm if there is significant or circumferential calcification. For those requiring a 23-mm Sapien TAVR, iliofemoral arterial sizes are 7.5 mm and 8.5 mm, respectively.

Whether alternate access routes are “allowed,” and will be reimbursed, is not clear. Alternate access routes have been successfully used for TAVR (eg, iliac conduit, transapical, trans-subclavian, transaortic and transcarotid). The transapical approach was studied in the randomized PARTNER I(A) trial, which randomly assigned such patients against standard cardiac surgery in high-risk patients (Society of Thoracic Surgeons [STS] score <10) and found the results to be noninferior. But other access for TAVR has not been studied in the United States in a systematic manner. Most US sites are cautious about using access routes alternate to the transfemoral route and are attempting to understand exactly what the inclusion criteria for the FDA and CMS wording imply. Thus, most US sites using “commercial” TAVR are making individual decisions concerning patients who have inadequate iliofemoral access but are otherwise TAVR candidates.

In addition, TAVR is covered for uses that are not expressly listed as an FDA-approved indication when performed within a clinical study. Ongoing research registries will be formed that will study outcomes in alternate access TAVR patients, making “off-label” use available to patients with aortic stenosis and also making outcomes in such patients part of our understanding of appropriate TAVR use.

Other options for TAVR

Small vessel registry: Patients can be enrolled in a nonrandomized registry if they are deemed inoperable and have iliofemoral vessels between 6 mm and 7 mm in diameter. This registry has numerical limits for each TAVR site. Many sites within the United States have already filled their quota of patients. When all sites in the United States have filled their quota, this registry will be closed. Whether there will be a “continued access” to TAVR for such patients is not known.
Inclusion in randomized US trials: The PARTNER II trial is currently enrolling patients with symptomatic aortic stenosis who are operative candidates and have lower risk (STS scores >4). Patients are identified for either a transapical or transfemoral approach, using the newer, smaller diameter Sapien XT device, and are randomized against standard surgical aortic valve replacement. The results of PARTNER II will help understand if lower-risk surgical patients with symptomatic aortic stenosis should be offered TAVR with the Sapien XT device.
Inclusion in other randomized US trials: The Medtronic CoreValve US Pivotal Trial encompasses two studies in different patient populations. The first is a study of patients at high risk for standard aortic valve surgery. Patients are randomly assigned to either TAVR with CoreValve or to surgical aortic valve replacement. The trial will include assessment of alternative implantation routes, including the subclavian approach. The second study is of patients at “extreme risk.” Patients deemed extreme risk will not be randomly assigned. Rather, this patient group will be evaluated against a performance goal derived from contemporary studies.

Options outside the US

In Europe and Canada, both the Sapien XT and the CoreValve (Medtronic) devices have achieved CE mark status. This makes them available for implantation outside of clinical trials. Other newer-generation TAVR devices such as JenaValve, DirectFlow, Sadra and Portico have also achieved CE mark status or are in phase 1 clinical trials. Experience with the latter devices is still limited compared with the thousands of implants of CoreValve and Sapien devices.

Peter C. Block, MD, is professor of medicine at Emory School of Medicine. He is also the Intervention Section Editor for Cardiology Today and is a member of the Cardiology Today Intervention Editorial Board.

Disclosure: Dr. Block is a proctor for Edwards Lifesciences and is part of a research site for the PARTNER II trial.