Stents are the Cardiovascular Interventionalist's "Best Friend". It was Andreas Gruntzig, a Swiss radiologist who first demonstrated in 1977 that occluded coronary artery can be opened with the use of a balloon. A few years later came the use of a "metallic mesh" called stents to complement the plain balloon angioplasty. With widespread acceptance, we soon realized that the use of stents is limited by restenosis (reocclusion of the artery). A phenomenon (Restenosis) secondary to remodelling that usually occurs between 6 months to 1yr from implantation. A second generation stent called "Drug Eluting Stent" (DES) was developed and indeed made a significant impact in reducing restenosis by as much as 50% vs bare metal stent.
Latey however, we have been bombarded with negative news regarding the increased incidence of stent thrombosis (blood clotting) causing an acute myocardial infarction >6months after DES implantation called Late Stent Thrombosis (LST) or even >1-3yrs after implantation called Very Late Stent Thrombosis (VLST). Current indications suggest that these events were limited to those who stopped the use of an antiplatelet drug called Plavix. This incidence is very small yet it is a cause for concern. Overall however, this hardware (DES) is still considered safe and effective and I can almost guaranty its continued use in the years to come.
Our existing guideline dictates the use of plavix for a minimum of 6 months after implant. To date, we don't really know the exact duration of plavix therapy however, current data do suggest that continued use of this drug for at east 3-4 years perhaps indefinitely after implantation maybe warranted until further information is available.
The US FDA is currently convening a panel of experts to study this phenomenon and certainly a new set of guidelines with be forth coming in the near future. Again, let me reiterate that the use of DES is not only safe but also effective albeit, with minor glitch that needs further refinements in terms of guidelines for our coronary patients.
Additional studies are definitely needed to answer the two major questions we have today. These questions include the safe duration for Plavix therapy post implantation and how to identify these subset of patients at risk for this dreaded complication. I shall continue to update this blog, most importantly on this issue as soon as a new set of guidelines are available.
