I'm going through my science reading for last week (I know, I'm late) and I'm shocked by this pair of articles from NEJM. The associated editorial might be clearer for some.

Basically, in the field of cardiology, the surgical intervention of choice for acute myocardial infarction (MI or heart attack) has been to stick a little tube (it's like an expandable net really) into the areas where the clot is obstructing the coronary vessel that feeds the heart muscle. This is called Primary percutaneous coronary intervention or PCI, and it usually involves stent placement (rather than plain balloon angioplasty) which is designed to reopen a clotted blood vessel and, hopefully, keep it open for the remainder of the patient's life. Here's a picture of one:



A critical problem is that the stent may open up a vessel in the short term, but over time, the cells will grow back and shrink the openining (the lumen) of the vessel again (this is called restenosis) potentially causing angina (chest pain with exertion) or another MI in the same spot. So, smart people decided the thing to do would be to coat the stents with a drug like paclitaxel or sirolimus, which ideally would inhibit the growth of cells back into the stent.

Sure enough, this worked, and studies showed that restenosis was less of a problem in these drug-coated stents. However, what has been less clear is whether or not this has actually improved outcomes. As these papers show, it appears not. From the editorial:

Thus, in the PASSION trial, nonsignificant trends in favor of the paclitaxel-eluting stent were found for target-lesion revascularization, death, and reinfarction, whereas in the TYPHOON trial, the sirolimus-eluting stent was associated with a significant reduction in the rate of target-vessel revascularization, with rates of death and reinfarction very similar to those in the uncoated-stent group. It would be dangerous to conclude from these data that one drug-eluting stent is better than the other in primary PCI, since direct comparisons of the two stents for this indication are not available. In the two studies, the design, inclusion criteria, and definitions of end points were indeed slightly different. Yet, the results seem to be in line with those of studies that have compared these two types of stents in elective procedures — namely, lower rates of restenosis and repeated intervention with the sirolimus-eluting stent without significant differences in myocardial infarction or death.
...
Because of the cost, the need for prolonged treatment with thienopyridine, and the risk of late stent thrombosis (especially after premature discontinuation of thienopyridine therapy), larger trials with hard clinical end points and longer follow-up are needed before routine implantation of drug-eluting stents can be recommended for all patients undergoing primary PCI.

In other words, these things did what they were supposed to, but when it comes to the most important outcome, repeat MI or death, they failed. As a result, the greater expense and use of drugs to allow patients to tolerate the stent may not be justified. This doesn't represent total death of drug-coated stents, but it's a major blow.

The other thing to realize is that many drug companies have been fighting viciously for marketshare for their various drug-eluting stents. One of the things about surgical procedures and materials is that they don't undergo the same FDA approval process as drugs do, so a new stent that's slightly fancier or uses a different drug-release profile can be released without an outrageous investment in clinical trials (although they still have to do basic safety and quality control testing). As a result, the market share of one stent versus another has swung wildly throughout the years, meaning billions of dollars swinging from one company to the next as they come out with the next best thing and trying to get surgeons or interventional cardiologists to jump on board.

I can only imagine the tears on Wall Street with this result (except for the non-coated stent types). That must be why last week I sensed a great disturbance in the financial force, like a million voices screaming out at once, then being silent.