Monday, October 24, 2011


One of the burning questions left in the use of Drug Eluting Stents ( DES ), is the optimal duration of Dual Anti-Platelet Therapy ( DAPT ). As we all know, the use of DES has definitely reduced the restenosis rates following PCI by reducing neo-intimal hyperplasia. However after 5 years of usage of DES ( back in 2006, Barcelona, EuroPCR ), we learned that the use of DES has spurn a new disease called Stent Thrombosis, be it acute ( due to procedural factors ), subacute, late, and very late. The last 3 varieties maybe due to reaction to the polymer or just local factors where the stent is deployed, or as some have suggested, accelerated atherosclerosis following DES implantation. Stent thrombosis carries a 100% risk of an acute myocardial infarction which results in a 30-40% risk of death. It occurs about 4% in the first year and about 0.5% yearly thereafter. Few are affected if your PCI volume is low, but when you consider 3-4 million DES implantation in USA per year, the problem is substantial.
So patients with DES are given a small sermon, about the importance of taking their DAPT. This is the best way to counter the issue of stent thrombosis ( besides deploying the stents better and also perhaps a better selection of DES ).
The next question the patient will ask is, for how long? as DAPT does have their problems. There is the issue of bleeding risk?, including strokes, the issue of non-cardiac surgery? and of course, the issue of cause, as clopidogrel, and now prasugrel, are not cheap drugs. They cause about RM3-400 per month. In fact, there is a strategy that if the patient cannot afford DAPT for 1 year, it may be better to implant bare metal stents. This issue is commonly faced in public hospitals where the patients may be poorer.
In the 20th October 2011 issue of Journal of the American College of Cardiology, Dr David Kandzari and colleagues studied the issue of duration of DAPT in patients implanted with the Endeavor DES. He compared the risk of stent thrombosis in those following 6 months of DAPT and those following 3 years of DAPT. There were 2,032 patients who had The Endeavor DES, followed for 3 years on DAPT. He found that there was no difference in MACCE rates following DAPT for 6 months or 3 years. The rates were the same. He concluded that for patients who had the Endeavor stent implanted, 6 months of DAPT should be sufficient.
Well, this sounds good and cost savings. In fact, we have all suspected this for quite a while, but many physicians just do not have the courage of stopping at 6 months because DES are implanted in such a great variety of anatomical conditions. Obviously, those patients with DES across the left main stem must need longer DAPT protection, perhaps for life ( unless contr-indicated ), those with complex bifurcation, those with long overlapping stents ( full metal jackets ), those with DES in situations of high thrombus loads, etc, etc. You see, there can be so many sub-clauses, that sometimes, I get so confused as to who, I can syop, and who I should not. Sometimes, it is the patient who request to stop, and I will look back on the PCI report and then decide.
Anyway, it is good to know that as least for one type of DES, we do not need routine DAPT for 1 year or more. I am sure that the interventionist in public hospitals, especially in Malaysia, will take note of this.
Looks like it may be a good marketing point for the Zotarolimus eluting stent.

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