International circulation:  As we know， you have done outstanding work on PCI in left main disease. Do you think stents can replace surgery in left main disease?

Dr. Park: Yes， of course I think it can. However， currently we are in somewhat of a transient period. We have changed from 100% surgeries to now a mixture of approximately 50% of cases handled by PCI and the remaining by surgical intervention. Personally， I think we cannot replace PCI with surgery 100%. A very selected group of patients had isolated left main disease， isolated main with a single vessel disease， a SYNTAX score less than 33， stenotic lesion disease those kind of lesions. Those kinds of patient subsets should be treated with PCI.

International circulation: What types of left main lesions would exclusively， in your opinion， be needed to be treated with surgery and wouldn’t be candidates for PCI?

Dr. Park: We actually don’t have enough data to know for sure.  First of all， based on our own registry data，  patients who had a very low ejection fraction less than 30%， very old patients， or patients who have had triple vessel disease should been treated with surgery.  However， the SYNTAX subgroups analysis clearly demonstrate that patients with a SYNTAX score more than 33， a high SYNTAX score， actually show that the PCI group had a higher morbidity rate and even a higher rate of mortality too.  Up to this point we really need to analyze more data， especially in terms of global multi-center studies， to have a clearer idea about which types of lesions benefit more from PCI. However， the complex lesion subset with a SYNTAX score more than 33 is a good candidate for surgery.

International circulation: There is still currently debate on the safety of the first generation DES. Whether next generation DES is better than first generation DES regarding the safety is unknown. What is your opinion about this problem?

Dr. Park: Yes， this is quite an intriguing issue. Up to this point， we have very limited data in terms of comparison with Cypher versus Taxus in the current practice. Many left main studies clearly show no difference in terms of Cypher versus Taxus. Actually， if you look at the comparison data， Cypher versus Taxus in many pilot studies， it has been clearly demonstrated that Cypher would be better in terms of clinical outcome，  ( from TNL， and TBL to TLR， TVR) However， the main vessel disease subset we haven’t found any difference because the main disease subset had a really big reference vessel diameter compared to the disease subset group， more than 35. So we cannot expect a big differences between the different stent types. However， for the second generation stent it depends more on the stent platform itself， such as big side-wall or sometimes a high radial force which may be better for the left main disease interventions. In terms of the two generations of stents， many meta-analysis studies have found no differences in late stent thrombosis among the different stent types including Cypher， Taxus， and Endeavor stent. We need more long-term data. In terms of Endeavor stent， it had biocompatible polymers associated late stent thrombosis after one or two years. Still the number of late stent thrombosis is quite small， and the data shows it is not a big concern in real practice.  Especially when you use the appropriate duration of asprin or other suitable anti-platelet therapy for at least one year after stent placement. 

International circulation: According to the latest data， more than 95% CHD patients in China were implanted with DES. However， it was much lower in Europe and America. What do you think about this difference?

Dr. Park: Even in Korea the degree of stent penetration is over 85%， almost 90% actually. There are technical developments in terms of the two generation of DES. So outcomes should be better. If we do not pay so much attention to economics， such as cost effectiveness， etc.， I would prefer to use DES over bare metal stents. Because it is quite better in terms of efficacy and safety concerns. Many physicians still worry about ( from these issues to late stent thrombosis. ) But personally， I believe there are no difference between DES and bare metal stents.

International circulation: What do you suggest goes through a cardiologist’s mind in Europe or America as to why they continue to use bare metal stents opposed to DES?  Could you address the large disparity between the use of stents in the two regions?

Dr. Park: In very specific patient subsets and lesion subsets， for example the very big vessel where the reference vessel diameter is over 4mm， the effective stent cross-sectional area is still the most important reason for choice of stent. Firstly， if we have a really large vessel， we can use a bare metal stent since we can get enough stent cross-sectional area. Secondly， we have some meta-analysis of infarct patients that clearly demonstrate， that DES must be better than the bare metal stents in terms of (from TBR to TVR.) However， they didn’t find any difference in terms of stent thrombosis or safety concerns such as mortality or myocardial infarction. Therefore， DES is a better option in my opinion. Some social or economic reasons may be more significant factors affecting physicians choices in stent selection.  For big vessel diseases bare metal stents seem to be okay.

International circulation: PCI for CTO lesion is still a big problem at present. What is the main problem of PCI for CTO? How to solve?

Dr. Park: CTO (please omit-in) intervention is really a hard issue in the interventional cardiology field.  The reason is that more than 15~20% of PCI patients include CTO lesions subset.  Totally recannualized vessel would be better than occluded vessel is our hypothesis.  For single vessel disease， actually we don’t really need aggressive PCI procedures for those types of patients since we know that in terms (please add-of)long-term survival and long-term mortality the outcomes are pretty much the same for patients who also had a CTO. So we have to clearly evaluate what the total disease status is for patients on an individual basis before the procedures. In terms of major vessel CTO we know that how disease status would affect long-term outcomes.  For those kinds of patients we need to carefully choose which PCI intervention should be used.