May 2, 2018
By now, almost everyone in need of aortic valve surgery has heard of TAVR (transcatheter aortic valve replacement). Many patients wonder if they’re TAVR candidates and if they are able to have their aortic valve replaced without open heart surgery.
TAVR has revolutionized the treatment of aortic stenosis, with shorter hospital stays, less pain, and quicker recovery times. Aortic stenosis results when the normally thin and pliable aortic valve leaflets become calcified and rigid, limiting their ability to open and close with every heart beat (see the aortic valve disease page). This essentially dams up the heart, requiring more and more force to get blood through the aortic valve. As the heart begins to fail, patients develop symptoms like chest pain, shortness of breath, or fainting. The only effective treatment for severe aortic stenosis is to replace the aortic valve.
The question then becomes TAVR or SAVR (surgical aortic valve replacement) and why? Or, if not TAVR, why not?
TAVR was originally approved only for patients who were too sick to undergo open heart surgery. After early successful results, though, indications were broadened to include patients who were “high risk” for SAVR. With further success, the TAVR application has now been expanded to patients deemed moderate risk for surgery, as indicated by their STS mortality scores. The STS mortality score is determined by entering risk and demographic factors such as age, diabetes, history of stroke, heart function, kidney and lung function into a sophisticated computer model developed by The Society of Thoracic Surgeons. A score of greater than 3 equates to moderate risk. The latest broadening of TAVR indications to include moderate-risk patients has greatly increased the number of patients with aortic stenosis who are eligible for TAVR. In addition, trials to determine the efficacy of TAVR in low-risk patients are now under way. This leaves patients who are borderline candidates or who are not TAVR candidates to ask why. In fact, some go so far as to shop around in order to find heart centers that will offer them TAVR instead of SAVR.
So, who is not a TAVR candidate and why not?
As you might expect, the answers can be complicated, but are designed to determine the best individual result for each patient.
- The optimal aortic valve replacement procedure should be one that is minimally invasive and has a high success rate. TAVR meets these criteria, with the patient experiencing minimal pain and short hospital stays. However, it is important that these excellent results be long term over the life of the patient. All aortic valve replacement therapies, including TAVR are made from cow or pig tissue (bioprostheses) and are known to degenerate over time. In fact, the younger the patient, the quicker the valves tend to wear out. It will be many years before we have enough experience to determine the durability of the TAVR valves that are currently available. This is particularly important in younger patients with aortic stenosis who will need their new aortic valves to last for two or three decades. Though some feel that replacing a worn out TAVR valve with a new TAVR valve will serve these patients, it is simply too early to tell. As such, younger patients (under the age of 70 or so) are probably better served with SAVR.
- TAVR valves are not suitable for all types of aortic valve disease. Experience with TAVR in patients with bicuspid valves (two aortic valve leaflets instead of the usual three) is somewhat limited. Also, the valves that are currently available are not approved for patients with pure aortic insufficiency (leaking aortic valves), because there may not be enough calcium in the valve to hold the TAVR valve in place. These patients are currently better served with SAVR.
- TAVR may not be the best therapy in patients who need surgical correction of other cardiac issues (such as coronary artery disease and ascending aortic aneurysms) in addition to their aortic stenosis. These patients may be better served with combined operations in which both the aortic valve and the coexisting cardiac issue can be corrected in one surgical setting.
- Surgical results for aortic valve replacement are excellent. Though it may sound old fashioned, we have more than 50 years of experience with surgical aortic valve replacement, and the short- and long-term results are excellent. Though early TAVR results are comparable, it will be some time before we know about their long-term performance.
- The TAVR evaluation is comprehensive and sophisticated. In order to receive a TAVR valve, each patient in the United States must be evaluated by a “heart team” consisting of at least one cardiologist and two cardiac surgeons. The team goal is to determine the best valve replacement therapy for each patient, based on age, surgical risks, complicating medical factors, and coexisting cardiac issues. If they are offering SAVR over TAVR, it’s because the heart team believes that it is the best option for that patient at that time.
Like all new and promising technology, TAVR will continue to improve with the ongoing development of newer and better valves and techniques. We also can expect further expansion to a greater numbers of patients. However, TAVR is not currently the solution for all patients, nor will it ever be.
If you are a patient with aortic stenosis, or have a family member with aortic stenosis, make sure that your heart team discusses both TAVR and SAVR with you, including the advantages and disadvantages of both. If you are not a candidate for a TAVR valve, understanding that your team believes that SAVR will give you the best long term result is important.
The opinions expressed in this article are those of the author and do not necessarily reflect the views of The Society of Thoracic Surgeons.
The STS mission is to advance cardiothoracic surgeons’ delivery of the highest quality patient care through collaboration, education, research, and advocacy.