International Circulation: I’m here with Dr. Ron Waksman here at C.I.T. 2009. Thank you for joining us today.

Ron Waksman: Thanks for having me.

International Circulation:  I’d first like to ask you to talk a little bit about the potential clinical use of ultra-sound or IVUS guidance in patients undergoing PCI with drug eluting stents， and do you agree with routine use of IVUS during PCI?

Ron Waksman: Perfectly. I think that IVUS has a big role in the guidance for drug eluting stents，perhaps even more role than we had with bare-metal stents. We have just published a paper in the European Heart Journal looking at our own data from the Washington Hospital Centre for all the patients that underwent IVUS guidance PCI versus those who did not. We found that for those patients who had IVUS guidance PCI， the rate of stent thrombosis was reduced， the rate of target region revascularization after one year showed a trend of reduction with a P value of 0.06. It was quite a big study because our utilization of IVUS is about 70% in our center， so we could in confidence say that if you take the approach of routine IVUS use for guidance you can definitely reduce events.

International Circulation: And obviously there are， I guess we could say， second generation drug eluting stents in clinical use and so does that increase the value of IVUS， does that influence whether you use IVUS or not， has that changed anything， do you feel?

Ron Waksman: Sure， what we have to remember is that one of the reasons for stent thrombosis is not so much related to the design of the second generations but to mechanical issues with the deployment， so if you do not have good expansion of the stent， whether it is a new generation or an old generation， there is a higher risk of stent thrombosis. There is a dissection at the end of the deployment that has not been covered， that has not been taken care of， that can increase the rate of sub-acute stent thrombosis， so I think for the first 30 days， this is more mechanical and can be eliminated by routine use of IVUS. As far as the very late stent thrombosis are concerned， we hope that the second generation are going to show us less stent thrombosis. That has to be proven， however， it is very difficult because that requires thousands and thousands of patients to be followed. So I cannot say so much about the IVUS for the long term， but for the short term and the first 30 days， which are the vast majority of stent thrombosis – about 0.6% of stent thrombosis within the first 30 days， so we can significantly reduce with the routine use of IVUS.

International Circulation: And do you think that IVUS has the potential to really influence treatment strategies for patients with coronary artery disease?

Ron Waksman: So， we have to differentiate. I think that it is a helpful tool. It is not going to give us all the answers， but for example when we see whether or not there is a calcified lesion or non-calcified lesion and if we need to prepare the vessel. We use it a lot also for pre-stent deployment because it helps us to choose the right stent size， the right stent length， to decide whether we can go direct stenting， so there are many questions that you can address prior to the stenting by assessment of the lesion， and obviously the decision of whether you need to post-dialate or not post-dialate. I don’t think that if you have someone with an intermediate lesion， of 50%， and you want to tell using intravascular ultrasound if that patients has to be treated or not， is there going to be progression or regression， that is very hard to tell. It can be a research tool， but we are not ready to use this information to implement therapy.

International Circulation: And what about other imaging technologies， such as OCT， how would you compare and contrast them and their use with IVUS in clinical practice.

Ron Waksman: OCT is on the rise， it has a beautiful resolution， much higher than intravascular ultrasound， so it has enabled us to see very closely whether the struts are covered with neointima formation or not. I think there has been a lot of improvement in the technology itself， it does not require any more obstruction of the blood flow， it does happen very quickly. However， there is more work on the processing and it is limited in terms of the depth of penetration， so it does not give you anything more in terms of depth. Whether it is going to replace IVUS， I do not think so. I think that it is an additional tool that will probably be used more for research right now， but I do not see it replacing IVUS. It probably also has more value for apposition of the stent and perhaps in the future to see if the stent is covered with neointima formation. You may say that you do not need to do a lot of therapy in the long term， so it may potentially give us some information about the healing of new generation stents， but I do not see that this is going to replace IVUS， not in its current version at least.

International Circulation: Do you think the need to occlude the artery and stop the blood flow was a real limitation of OCT.

Ron Waksman: Well， clearly. I mean， there is a great improvement now with the new generation of OCTs which are much easier to handle during the procedure. But， the interpretation takes time， and you have to realize that one of the reasons that IVUS is not utilized in more than 12% of the population in the U.S.  - in Japan it is 70% and I do not know exactly what percentage in China but it is maybe even less than we have in the U.S. - the reason is because of the complexity of the analysing and interpretation. Even though it seems not so difficult to those of us that do a lot， there is a learning curve of looking， interpreting the images， measurement， and that is going to be even more difficult with OCT. So， I do not think the penetration of is going to be very high or exponential， despite the fact that it is much easier with the second generation OCT compared to the first generation， because obstruction of the vessel for thirty seconds was an issue， flushing was an issue， I think stabilization of the image was an issue. These things are continually being improved， and one day only the depth of penetration will be an issue. But， it does give you a beautiful resolution that you cannot see with IVUS. So， those who are interested in research， or very keen about imaging of the vessel may use both of them.

International Circulation: And how about improvements when we talk of IVUS? What are the things that need to be improved with IVUS， or perhaps some recent improvements that you can talk about.

Ron Waksman: So the recent improvement is that it is more user-friendly. You do not have to roll the big machine into the room any more because it is integrated in the cath lab. So the operator does not have much to do – it can all be handled from the cath table， which makes it easier. I think the resolution has been slightly improved with one of the systems and the other system continues to have very good imaging. I think， more or less， that overall we have reached the highest possible level of IVUS technology. There is always room for some improvement， but I think this is all we are going to get from this technology， maybe a little bit more helpful in operating and interpretation， edge detection and so forth， maybe voice activation in the future， but I think we are nearly there.

International Circulation: Are there any other trends that you see in the future with imaging in general， not just limited to IVUS?

Ron Waksman: So， it is interesting that you ask that. There is now an attempt to look more at morphology of the ve