International Circulation:  For these second generation stents what problems do you still see?
　　Prof David Kandzari: I think these fall into twofold. Number one we are still seeing progression of repeat revascularization after around a year or 9 months after the trial endpoint and so we know that events continue to occur in some patients. This is due to failure of efficacy， late stent stenosis with selected drug eluting stents and very late stage thrombosis. Part of the late thrombosis issue is that we are now very careful in following these patients. When bare metal stents were first approved they were approved on thirty day data with no plans for long term follow up so we never knew if it was a anecdotal clinical observation whether these events can occur late as well. And now that we are following patients more carefully we do recognize that events do persist. Another is the perceived lifetime commitment for some doctors for dual anti platelet therapy in patients with these stents. If we can test these new stents and new strategies such as shorter durations of anti-platelet therapy or in complex diseases such as left main disease I think this is the direction where new DES trials should be moving rather than trying to get a new product in the market.
　　International Circulation: Is it not difficult to keep patients on lifelong anti-platelet therapy?
　　Prof David Kandzari: I am a big proponent for shorter durations of anti-platelet therapy or at least evaluate them not because think patients should be taken off therapy after 6 months but because we recognize that adherence or compliance over long term follow up despite our best intentions just does not occur in real life practice. Even in contemporary trials by 5 years maybe 25%-30% of the patients are still taking aspirin and clopidogrel therapy.  I will like to remind clinicians that  we just do not have evidence that staying on long term anti-platelet therapy actually is going to reduce the risk of stent thrombosis.