TAVR is not the ‘beginning of the end’ for aortic stenosis open heart surgery
June 6, 2019
In March 2019, media outlets hailed two new studies on transcatheter aortic valve replacement (TAVR) as signaling the beginning of the end of open heart surgery for aortic stenosis.
Data from these studies suggest that, if the FDA approves TAVR – a procedure replacing a narrowed aortic valve through a small incision, as opposed to open heart surgery – for patients with low surgical risk, it would be a minimally invasive treatment option for a much wider pool of patients. As many as 50 percent of patients with aortic stenosis are low surgical risks.
In the future, how we treat these patients is likely to change. And, although the data are very intriguing, the excitement is a bit premature.
What isn’t apparent in the news and online – and is bound to disappoint a lot of patients – is that TAVR is not currently approved by the U.S. Food and Drug Administration (FDA) for patients with low surgical risk. Only patients who have an intermediate to high surgical risk, or those too sick for open heart surgery, can have TAVR today.
In other words, open heart surgery is still the best option today for patients with aortic stenosis who have a low risk of dying following surgery (less than 3% risk of mortality at 30 days).
Still, we already have patients who are scheduled for surgery but want to switch to TAVR. Some are concerned about how open heart surgery is portrayed in the media, such as in this article in The New York Times that refers to “cracking open the ribs” and “stopping the heart.” While medically accurate, that type of verbiage is likely to be scary to patients and overly dramatic.
It’s understandable that patients are excited about TAVR, which offers immediate benefits of shorter recovery and less time spent in the hospital. But there are numerous long-term unknowns surrounding TAVR for low surgical risk patients. Before we dive into that discussion, let’s go through the research that everyone is talking about.
Details about the studies
Two separate studies presented at the March 2019 American College of Cardiology conference supported similar findings: After one to two years of follow-up, TAVR outcomes were found to be similar to surgical aortic valve replacement (SAVR) outcomes in patients with aortic stenosis and low surgical risk.
In a TAVR procedure, a doctor can repair a
diseased aortic valve without open heart surgery. The new heart valve is
inserted via catheter through an incision in the groin, guided inside the
affected valve, and expanded to reopen it. Currently, the FDA has approved TAVR
only for patients who are at intermediate to high-risk for surgery. Approximately
half of patients with aortic stenosis today are considered to have low surgical
risk – hence the excitement about these studies.
Medtronic’s trial studied the CoreValve platform. Researchers assessed two endpoints after two years: death and disabling stroke. This study found that 5.3 percent of patients who had TAVR died or suffered a disabling stroke compared with 6.7 percent of patients who had surgery. All-cause mortality rates were the same for both procedures. Disabling stroke affected 1.1 percent of TAVR patients and 3.5 percent of surgery patients. The mean age of participants was 74.
The Edwards Lifescience’s trial studied the SAPIEN 3 valve. The three trial endpoints were death, stroke, or re-hospitalization after one year. These data showed that outcomes with TAVR were significantly better than outcomes with surgery. After a year, deaths related to stroke or re-hospitalization related to the disease, valve, or procedure occurred in 8.5 percent of patients who had TAVR and 15.1 percent of patients who had surgery. The mean age of participants was 73.
Two competing medical device companies. Two sets of similar short-term data. It’s interesting stuff. But I am concerned that we do not have enough information to make sweeping recommendations just yet.
While I think it’s reasonable to consider TAVR for the right patient population, low-risk patients should recognize the risk and uncertainty baked into that decision. Their TAVR procedure could be done well, giving them reliable 10- to 15-year outcomes. Or TAVR could benefit the patient only in the short-term.
Her heart was failing only a few years after a valve replacement, but it wasn't clear why. Examine the scan, put on your medical detective hat and see if you can form the right diagnosis. Dr. Kumbhani will provide the answer in the video at the bottom of this article.
3 concerns about the TAVR studies
1. The data are too short-term, and patients might need surgery later.
The studies followed patients for only one to two years. Data showed that these patients had similar or better outcomes compared to surgery in the short term. However, aortic stenosis is a degenerative disorder, so it is more common in older patients. And because TAVR candidates have traditionally been a sicker cohort, we do not have substantial data on the effectiveness of TAVR beyond five years or so after placement.
Medical literature suggests that the lifespan of the tissue valves used in surgical aortic valve replacement is typically around 10 to 15 years. Since TAVR valves are made of the same biological tissue, it is expected that they will have the same longevity. However, we don’t have data to verify that. After the valve wears out, a patient will need to have a new valve placed or have another valve implanted during open heart surgery.
A 65-year-old patient likely will be expected to live longer than 10 to 15 years after surgery, so durability of tissue valves must be validated. Valve replacement or revision might be simple if the patient can have another TAVR procedure – a new tissue valve can be placed inside the previous valve. But if the patient needs surgery, the doctor would have to remove the existing valves and then replace them. Unfortunately, most surgeons do not have a lot of experience in removing CoreValve and SAPIEN 3 valves yet, which could pose a risk to patients.
2. TAVR in low-risk patients is not yet FDA-approved, but people want it now.
When patients with low surgical risk call and want to switch to TAVR, we give them the facts. The procedure is not yet approved for patients with low surgical risk, and surgery is the best option for them. But if the FDA approves TAVR for this patient population, the conversation could get tricky.
While I think it’s reasonable to consider TAVR for the right patient population, low-risk patients should recognize the risk and uncertainty baked into that decision. Their TAVR procedure could be done well, giving them reliable 10- to 15-year outcomes. Or TAVR could benefit the patient only in the short-term (shorter hospital stay, shorter recovery), but the patient might need additional surgery in the future.
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Also, it is important to realize that patients who were eligible for mechanical valves were excluded for these trials. Typically, patients younger than 60 years of age are offered mechanical valves. Mechanical valves are designed to last for the rest of a patient’s life, and the probability of needing a new or revised valve is low. There are also certain anatomical considerations. Patients with bicuspid valves also were excluded from these trials. Patients with bicuspid valves develop aortic stenosis earlier in life and may frequently be low-risk patients.
3. The benefits of TAVR may not yet balance potential long-term risks.
Patients who get TAVR likely will have a shorter recovery. There are no bones and muscles to heal – just some tenderness in the groin incision.
However, is the risk of needing another TAVR procedure or a potentially complex surgery down the line preferable to these benefits? Some patients might say yes. But as a doctor, I say we need more research to determine the safest route – especially because we know surgery provides good outcomes for low-risk patients today.Another important consideration is a risk of forming clots on the tissue valves. First described for TAVR valves in 2015, it is frequently asymptomatic and requires a CT scan for a definitive diagnosis. We don’t know if clots are more frequent with TAVR valves compared with surgical valves, but current literature suggests that about 1 in 10-15 patients undergoing TAVR might develop this condition. In fact, as part of the trial design, it is required that approximately 300 patients in both the low-risk trials undergo follow-up CT scans to accurately assess the incidence of this problem and determine whether it is different between TAVR and surgery. The long-term significance of these clots and the best way to treat them also is not completely understood.
The future of TAVR
The landscape is going to be very interesting over the next few years. I imagine that valve manufacturers will do a lot of direct-to-consumer advertisements to sway people against open heart surgery in favor of TAVR. And for some patients, that might be a good option. We’ll be able to say that more confidently once we have long-term data on the safety and durability of TAVR valves.
I empathize with patients who want minimally invasive options. It has to be frustrating to be told that surgery is the only choice today. But know that the heart team at UT Southwestern’s Clinical Heart Center has our patients’ best interests in mind. We want to give our patients more healthy years to enjoy the people and activities they love.
Above all, we want our patients to get the right treatment that will give them the best results for their unique condition. And the best way to do that is to gather long-term data and help patients make informed decisions about their care.
Medical Mystery: Revealed
Dr. Kumbhani and his colleagues across the country said this was one of the most challenging cases they had seen in recent memory. But they followed the clues and ultimately saved the patient. Did you solve the case, too?