Yesterday, in the first day of a 2-day meeting of the FDA's Circulatory Systems Devices Advisory Panel on drug-eluting stents (DES), the panel agreed unanimously that for on-label usage of DES, while there is an increased risk of late stent thrombosis (occlusion of the stent due to formation of a blood clot), there is no overall increase in risk for death or heart attack with DES as compared to bare metal stents. However, there is also no decrease in death or heart attack compared to bare metal stents.
"On-label usage" means that stents are used exactly as the FDA originally approved them - that is, for discrete, new (i.e., previously untreated) partial blockages in patients' native coronary arteries (i,e, not in bypass grafts), and only in relatively large-sized vessels. DES were approved for this kind of usage because the studies that were done to demonstrate the initial efficacy and safety of DES were limited to these kinds of coronary artery blockages. In the real world, however, reports have estimated that at least 60% of DES are being applied to "off-label" usage. Such off-label usage includes the treatment of acute heart attacks, of restenosis occurring with previous stents, of blockages in bypass grafts, of complex coronary artery lesions, and of small blood vessels.
The panel's conclusion that on-label usage does not yield an overall increase in risk was reached after a long day of hearings in which the panel listened to numerous presentations of clinical data, and hours of ensuing debate.
Regarding the use of clopidogrel (Plavix) and aspirin after DES placement, the panel fell back on their mandate to only recommend changes to product labeling when there is clear data from randomized trials to support such changes. There are no randomized trials that were designed to answer this question. Thus, the panel recommended no real change to the FDA labeling of 3 months of Plavix after receiving a Cypher stent and 6 months after a Taxus stent - but they did support language from a recent American College of Cardiology/American Heart Association statement that patients ideally stay on Plavix and aspirin for up to a year unless the risk of bleeding is high.
The panel will take up the off-label usage of DES in their deliberations today.
