Can you tell us about the structural heart program at Mount Sinai?
Ever since transcatheter aortic valve replacement (TAVR) technology was first introduced to the United States, we have had a TAVR program at Mount Sinai. We began performing TAVR as part of the original CoreValve pivotal trial and it has now been almost 10 years.
The structural heart program at Mount Sinai has since grown significantly, including TAVR’s most recent indication for low-risk patients. In our main hospital site, Mount Sinai is on track to perform at least 360 TAVRs by the end of 2019; adding in our sister site, St. Luke’s, means we will be well over 400 TAVRs.
As the structural heart program’s surgical director, can you share some of the aspects of your position?
We have a comprehensive heart team consisting of interventional cardiologists, cardiac surgeons, imaging specialists, and heart failure specialists. I am the program’s surgical director, so I am the surgeon dedicated to the structural heart program and the primary surgeon for all the transcatheter valve procedures at Mount Sinai. I perform TAVR, MitraClip, transcatheter mitral valve replacement, and transcatheter tricuspid valve repair and replacement procedures. I am also in charge of the pre-case planning of all transcatheter valve procedures, including detailed computed tomography (CT) scan analysis and work with our structural heart echocardiologists on evaluating patient’s anatomy and candidacy for transcatheter valve procedures.
Why study transcatheter aortic valve positioning in relation to native aortic leaflets?
We are seeing more patients who are younger and at lower surgical risk being treated with TAVR. TAVR is fundamentally different from surgery, in the sense that during surgery, the native aortic valve leaflets are removed. Thus, when a surgical valve is implanted, there is no barrier that would make accessing the coronaries after surgical aortic valve replacement difficult. TAVR, on the other hand, relies on the native aortic valve leaflets to anchor the valve securely. Not only do the native leaflets become a barrier, but the frame of the transcatheter valve also creates a potential barrier to access the coronaries. In a previous study1, we found that if you look at the CT scan of these patients after TAVR and evaluate how the valve commissures align relative to the native commissures, the result is essentially random. More than 50% of patients will have a commissural post in an overlapping position with one or both coronaries, which can create a barrier in addition to the native leaflet for coronary access. We know that even after we fix the aortic valve and relieve the aortic stenosis, many of these patients have mild and moderate coronary artery disease that may progress with time, even though the published rates are relatively low. Assuming that TAVR devices have good durability of up to 10 years or more, the progression of coronary artery disease will eventually require potential diagnostic or therapeutic intervention. Future coronary intervention is a very important consideration as we expand TAVR to younger patients, because we would not want a situation where the valve is working perfectly well, but then the patient suffers a heart attack or some kind of acute coronary event that might jeopardize their survival.
There has always been a focus on valve positioning, but it is interesting how your research further refines that discussion.
When the TAVR trials were first initiated, we just wanted our patients to live. Remember that first-generation devices still had relatively high rates of paravalvular leak and stroke, so people were just happy that patients survived. As the technology improves over time, the importance of surgical risk stratification has reduced. We are now talking more about making sure stroke, pacemaker, and paravalvular leak rates are at a minimum. We are considering how to manage these patients in a lifelong fashion, rather than just putting in a valve at this time and hoping for the best down the road. Now the whole community, cardiologists and surgeons doing TAVR, are focused on how to be responsible and do this procedure right the first time, with current technologies, so that we can anticipate lifelong management of these patients.
Can you tell us more about how the study was performed?
One of the challenges in our previous study was doing post-TAVR CT angiography (CTA), because it increases radiation and intravenous contrast exposure to the patient. So a post-TAVR CTA is not practical beyond perhaps a research study. However, we developed a technique to incorporate a certain fluoroscopic view that can be matched to the pre-TAVR CTA. It is matched in such a way that the valve orientation can be mathematically determined, allowing us to avoid a post-TAVR CTA. Some of these patients did have a post procedural CTA so we could validate this methodology. We have looked at two valves that are commercially available, the Sapien 3 valve (Edwards Lifesciences) and the Evolut valve (Medtronic). With the Sapien 3 valve, we tried crimping the valve at specific orientations (3, 6, 9, and 12 o’clock) before we insert the delivery catheter and deploy the valve. What we found was that despite crimping the Sapien 3 at specific orientations, there was no preference on commissural alignment.1 We then went on to do the same thing with the Evolut valve.2 The Evolut valve has a “hat” marker on the delivery catheter visible on fluoroscopy. In about 60% of our cases, the hat marker was at the outer curve of the aortic root. When we co-registered the fluoroscopic image to the pre-TAVR CTA, we found that these patients typically would have the C tab, which represents one of the commissures in the Evolut valve, located at the inner curve of the aorta. This particular orientation at the time of deployment offered the best chance to achieve commissural alignment and avoid having a commissural tab facing the left main or right coronary artery. Our findings were provocative, because for a long time, most people believed that it is not possible to control the orientation of any transcatheter valve. We went on to present our study at TCT in 2019 with data from over a hundred consecutive patients receiving the Evolut valve, where the delivery catheter orientation was actively controlled in order to permit optimization of commissural alignment with the Evolut valve.
Can you further describe the hat marker on the Evolut valve and how the positioning works?
The hat marker is on the valve delivery catheter capsule, allowing the operator to view its position very clearly. If the delivery catheter is inserted into the patient’s femoral artery with the flush port facing away from the operator, meaning at around the 3 o’clock position, over 90% of the time, the hat marker will end up at the outer curve of the aortic root and there is a strong chance of achieving good commissural alignment. This flush port facing at the 3 o’clock position during initial catheter insertion is safe and doesn’t change anyone’s deployment technique. We have now done over 150 consecutive cases using this technique and there have been zero complications due to this modified technique. Commissural alignment improves the ability for coronary access, because you will not have a commissural post facing the coronary artery. For a transcatheter valve with a tall frame, this means there are more cell openings available for coronary catheters to engage against the coronary orifice in order to perform diagnostic or therapeutic intervention.
Did this study increase your use of the Evolut valve?
Both the balloon-expandable and self-expanding valves are excellent. We typically have based our valve choice on clinical and anatomic factors. Having said that, I think 85% of the time, the anatomy is going to be suitable for either valve, so it is more of the operator’s preference, and we are not shying away from the Evolut valve. In fact, we like the supra-annular hemodynamic benefit of the valve with low valve gradients, which we think may impact valve durability. We have achieved very low pacemaker rates that are comparable with balloon-expandable valves. It is at most 6-8%.
Have any patients since come back requiring coronary intervention?
A couple patients have come back requiring diagnostic angiography. It was nice to hear from our interventional cardiology colleagues that it was very easy to reaccess the coronaries, given the commissural alignment. They found it much more straightforward than not knowing the position of the commissures.
You are preemptively addressing a relatively new issue — coronary access post TAVR.
Right. We have a very high percutaneous coronary intervention (PCI) volume at our center, so we don’t have a lot of technical concerns dealing with these issues. But you can imagine the community interventional cardiologists who are not familiar with TAVR and not familiar with these devices, and who have to deal with acute coronary syndromes or ST-elevation myocardial infarction. Because they just see that TAVR valve frame as a barrier, without knowing where the commissures are, they believe coronary access after TAVR can become challenging. Our study has found a way to perform TAVR in a more predictable manner that offers a higher likelihood of commissural alignment. Certainly, in patients with commissural alignment, it is not dissimilar to doing a diagnostic cath or PCI in someone with a surgical aortic valve replacement. No one thinks twice about coronary access after surgical aortic valve replacement, because commissural alignment is not an issue in those patients. With proper commissural alignment in a TAVR patient, it is just a matter of engaging through the valve frame to access the coronaries.
The amount of time to incorporate this technique is minimal?
It is actually zero, because 90% of the time when you insert the delivery catheter with a flush port facing away from the operator at 3 o’clock, it achieves commissural alignment reasonably well. When you advanced the delivery catheter along the descending aorta, you just need to make sure that the hat marker is on the outer curve and if so, more than 90% of the time, it works. We have had to rotate the delivery catheter at the descending aorta <5% of the time to get the hat marker to the outer curve and when we do that, we can usually get the hat marker to the outer curve at the aortic root during Evolut deployment to achieve commissural alignment.
What was the reaction to your presentation at TCT?
People were very interested. I think this is a topic that has not been raised before, meaning coronary access and commissural alignment. It also has implications in those patients who might need a future TAVR down the road. If you think about it, having a commissural post facing or near a coronary means that for a redo TAVR, you could potentially obstruct the coronary because the TAVR leaflets would be pinned against the valve stent frame. People have pointed out other techniques, such as BASILICA where the leaflet is split, that might be able to avoid that concern. The problem is that a TAVR valve is not a surgical valve, and in most cases, we don’t have commissural alignment with TAVR. If the commissural post is near one of the coronaries, you cannot use the BASILICA technique to split a commissural post — that is just physically not possible. With commissural alignment, however, at least you can consider it as an option, if the patient down the road requires valve reintervention. It may perhaps be feasible to do BASILICA then a TAVR-in-TAVR instead of open heart surgery. With commissural alignment, at least we prepare future interventionalists down the road to address this issue rather than getting stuck with a problem that they cannot physically solve. There are two TAVR devices that require commissural alignment for deployment: JenaValve (JenaValve Technology, Inc.) and J-Valve (JC Medical), but they are still in clinical trials, so we would have to wait for some time before they are FDA approved. I suspect these TAVR valves that require commissural alignment may be better suited in younger patients where redo TAVR may be a potential option.
Would a second TAVR be required because of valve dysfunction or would it result from reaching the end of the valve’s natural longevity?
We don’t know the answer to that. It’s still too early. We don’t yet have 10-year data, but so far the 5-year data is promising. There is an interesting question of whether commissural alignment in low-risk TAVR patients, as with the surgical valve, may have some hemodynamic benefit in terms of coronary flow and perhaps may improve valve durability. Again, this is a hypothesis-driven question. We don’t have the long-term data, but certainly we can suggest doing some in vitro benchtop testing for further evaluation.
Disclosures: Dr. Gilbert Tang reports he is a physician proctor for Edwards Lifesciences and Medtronic, and a consultant for Medtronic.
Dr. Tang can be contacted at firstname.lastname@example.org.
- Tang GHL, Zaid S, Ahmad H, Undemir C, Lansman SL. Transcatheter valve neo-commissural overlap with coronary orifices after transcatheter aortic valve replacement. Circ Cardiovasc Interv. 2018 Oct; 11(10): e007263. doi: 10.1161/CIRCINTERVENTIONS.118.007263.
- Tang GHL, Zaid S, Gupta E, Ahmad H, Patel N, Khan M, Khan A, Kovacic JC, Lansman SL, Dangas GD, Sharma SK, Kini A. Impact of initial Evolut transcatheter aortic valve replacement deployment orientation on final valve orientation and coronary reaccess. Circ Cardiovasc Interv. 2019 Jul; 12(7): e008044. doi: 10.1161/CIRCINTERVENTIONS.119.008044.