Transcatheter aortic valve replacement, TAVR. Transcatheter aortic valve implantation, TAVI. Dr. Anton Titov, MD. How to compare these two methods? Dr. Jeffrey Popma, MD. A minimally invasive method of aortic valve replacement. And open-heart surgical operation to replace aortic valve. You have actually brought up some very interesting terminology to start with. First of all, you have mentioned the transcatheter aortic valve replacement or TAVR. That's the US version. That has to do with clinical reimbursement issues. Dr. Jeffrey Popma, MD. You have also mentioned the Transcatheter Aortic Valve Implantation, TAVI. It is the European terminology for the same procedure. Because that has been more of an intervention rather than a replacement. That TAVR and TAVI we use synonymously. But it must be very confusing to people when we talk about it. Dr. Anton Titov, MD. One abbreviation is the US based, the other is of European origin. This whole journey about trying to do something less invasively has been a 10 to 15 year history. Certainly it is been an eight-year history for us here at our hospital. We had initially felt that some sort of lesser invasive technique for helping patients is good. We wanted to have relief of their aortic stenosis. It was a very laudable goal. The technology that we had in the early days was very different. Dr. Anton Titov, MD. The technology that we have available today is better. Dr. Jeffrey Popma, MD. Things have really changed. We began our early comparisons of aortic valve surgery versus TAVR in the United States. We took the patients who were deemed to be inoperative. Patients were not able to have a regular aortic valve replacement operation. Dr. Jeffrey Popma, MD. Those patients were extremely high-risk. We did randomized clinical trials on those patients. TAVR / TAVI came out to be superior both in terms of improvement of quality of life and quantity of life. These are very important metrics. In addition, TAVR was less invasive. Dr. Anton Titov, MD. Patients were moving around a little bit more quickly. About five years ago we started a clinical trial with the core valve device. It is called SURTAVI. That was implanted into intermediate risk patients. Those patients that had a risk of over 3% from 30-day mortality after surgery. We did a randomized clinical trial with TAVR. Dr. Jeffrey Popma, MD. We presented that at the ACC meeting. We published the results in a New England Journal of Medicine. Sure enough TAVR was not inferior to surgical aortic valve replacement. TAVI was associated with a more rapid improvement in quality of life. There were numerical reductions in strokes 30 days after surgery. Dr. Jeffrey Popma, MD. We found that TAVR / TAVI is really a preferred therapy for aortic valve stenosis. But the durability of the aortic valve is not fully known. But nevertheless TAVR is a lesser invasive procedure for patients to be able to become more mobile. Today there is been a rapid acceleration of growth of the transcatheter aortic valves. Especially in patients who are intermediate or higher risk. TAVR / TAVI is almost the preferred therapy. Dr. Jeffrey Popma, MD. We are looking at outcomes, looking at patients, looking at how many patients will get treated. We have gone from 2 TAVR cases every other week to now six TAVR cases per week. Dr. Anton Titov, MD. That is really accelerated in terms of the growth for patients. But we still have some unanswered questions on TAVR compared to open heart aortic valve replacement surgery. Dr. Jeffrey Popma, MD. We don't know whether TAVR is not inferior to aortic valve replacement surgery in some patients. Patients who are low risk for surgical aortic valve replacement. Dr. Anton Titov, MD. Sometimes I said to you. "Your chance of making it to 30 days and not having a stroke is 97% or greater”. It is true for aortic valve replacement surgery in low-risk patients. You should say. "That sounds like a pretty good deal!" I get an aortic valve that we know a lot about. It is going to be durable. That is been the only operation for a while. we don't know if the durability of our newer aortic valves. We are not fully confident in the issues related to coronary access. Dr. Jeffrey Popma, MD. There are matters related to cardiac pacemaker implantation. It does occur with more frequency with TAVR than with the surgical aortic valve replacement. We don't know those issues. So we are doing a randomized clinical trial now here in the United States, and in Europe, Canada, and Australia. We will randomize patients who are low-risk to either surgical aortic valve replacement or to use of the Evolut developed systems here. The Sapien TAVI device that PARTNER 3 clinical trial is running a similar trial across the world. Dr. Jeffrey Popma, MD. We have really made a lot of progress. In patients who are at high risk for surgery, probably TAVR is a very reasonable choice. For patients over 80 - 85 years of age, probably TAVR / TAVI is a reasonable choice. Because the recovery is so much quicker. But we haven't sorted out how the TAVR aortic valve performs yet in the lower risk patients. Dr. Anton Titov, MD. How TAVI aortic valve performs in patients with bicuspid aortic valve disease. How TAVI aortic valve performs in patients who who are much younger. Because we don't understand the TAVR valve durability. Dr. Jeffrey Popma, MD. A lot is in flux right now. We have learned a lot about TAVR. But we have a lot more to to gain as well.