What You Should Know About TAVR
Here’s what you need to know about TAVR, a growing option for patients with severe aortic stenosis who are at high risk or extreme risk for valve replacement surgery
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Many elderly patients with severe aortic stenosis (AS) have comorbidities that put them at high risk for surgery. An estimated one-third of patients with AS who need valve replacement are never referred for treatment, because their primary physician feels they will be unable to withstand an operation. Transcatheter aortic valve replacement (TAVR) is a growing option for these patients.
TAVR is a method of inserting a new aortic valve within a damaged valve through a catheter inserted in the groin, the apex of the heart or the aorta or one of its branches. The prostheses contain valve leaflets sewn into large stents similar to those placed in the coronary arteries. Most models are expanded by a balloon; some are self-expanding.
The PARTNER study was key to our understanding of how TAVR compares with conventional treatments for AS. In PARTNER B, 358 patients considered inoperable due to extreme risk were randomized to standard medical therapy or TAVR performed from the groin. A 20 percent absolute difference in all-cause mortality, was seen at one year, demonstrating conclusively that patients with severe AS who cannot have surgery may gain tremendous benefit from TAVR.
In PARTNER A, we assessed 699 patients who were deemed operable, but high risk. The patients were randomized to open valve replacement or TAVR performed transfemorally or transapically. In all endpoints—mortality, cardiovascular mortality, hospitalization and stroke—TAVR was not inferior to surgery. In valve area and gradient, 6-minute walking distance, NYHA class and quality of life as measured by KCCQ, TAVR outcomes were similar to surgical outcomes. Based on these results, TAVR was FDA-approved for high-risk operable patients.
The PARTNER trial was conducted with balloon-expandable prostheses. Studies conducted with the self-expanding prosthesis in patients at extreme risk were also favorable. In one trial that included high-risk patients, TAVR performed with a self-expanding prosthesis appeared to be better than surgical aortic valve replacement.
No procedure is free from complications. A number of complications of TAVR have been identified; however, four account for the majority of problems. In each of these areas, we are making progress toward ameliorating the problem.
The first is major stroke. Smaller devices and delivery systems now pass through vessels more easily. Additionally, we are more knowledgeable about patient selection and use of anticoagulation. We are currently testing filters designed to protect the brain from debris created during the procedure.
The second is major vascular complications arising from vascular trauma in the groin. Use of smaller sheaths, improved technique and better patient selection have decreased the incidence of this potentially devastating complication.
The third complication is paravalvular aortic regurgitation (AR). Because the TAVR prosthesis is not sewn to the wall, it may not fit tightly when the native valve is irregular, causing AR. New valve designs and the use of 3D CT scanning to better select the appropriate-sized device have reduced the incidence of AR substantially.
The fourth problem is acute renal injury. Because many elderly patients have underlying kidney disease, we now take measures to protect the kidneys by minimizing contrast and ensuring blood pressure remains normal to low.
AS is a complex problem, and patients are often very sick. For this reason, selection of the most appropriate treatment for any patient with AS should be made by a team that includes an imaging specialist, clinical cardiologist, interventional cardiologist and surgeon, with other specialists, such as a neurologist or geriatrician, included as needed.
It is important for the team to understand the patient’s symptoms, complaints, limitations, values and wishes, and to review an echocardiogram, catheterization and CT of the vascular system to determine the best treatment strategy for the patient. If the risk for surgery is not high, surgical valve replacement should be recommended. If the risk is high or extreme, TAVR will be appropriate.
Device manufacturers are working diligently to solve the technical problems of TAVR. Valves are now uniformly delivered through smaller sheaths. Some new stents are repositionable, and the latest generation of valves is designed to eliminate AR altogether.
We are excited about emerging indications for TAVR. Valve-in-valve TAVR, in which TAVR is used in bioprosthetic valve failure, is very promising. We are also conducting comparative trials of TAVR in intermediate-risk (moderate-risk) patients, in patients with severe AS and coronary artery disease and in patients with AR.
The good news is that with multiple national registries around the world, the collection of data on TAVR is highly disciplined. The Society of Thoracic Surgery/American College of Cardiology is prospectively recording all TAVR procedures performed in the U.S. through their TVT Registry, which now contains 28,000 records. This registry will be helpful in improving the quality of TAVR by detecting deficiencies and differences in patent characteristics and outcomes. Ultimately, the knowledge will allow us to serve our patients better.
Dr. Tuzcu is an interventional cardiologist and Vice Chair for Clinical Operations in Cleveland Clinic’s Robert and Suzanne Tomsich Department of Cardiovascular Medicine.