CardioSource WorldNews Interventions | In the April/May edition of Cardiosource World News Interventions, I wrote an editorial asking whether bare metal stents (BMS) should, or could be eliminated from cath lab inventory. The discussion at that time centered on two studies – the ZEUS and the LEADERS-FREE trials. The ZEUS trial showed that in patients with high bleeding risk and in of need coronary stenting, dual anti-platelet therapy (DAPT) for 30 days had greater safety and efficacy in patients who were treated with drug-eluting stents (DES) rather than BMS. All trials have cautions attached, and ZEUS is no exception. ZEUS was not conducted with contemporary stent platforms, so broad-brush conclusions are not possible. The LEADERS-FREE trial compared a polymer-free drug coated stent using umirolimus to a similar BMS in patients with high bleeding risk. All patients were mandated to have only 1 month of DAPT. A composite primary end point (cardiac death, myocardial infarction, or stent thrombosis) (9.4% vs. 12.9% in the DES group and BMS groups respectively) showed non-inferiority. But in LEADERS-FREE, need for target lesion revascularization was less in the DES group (5.9% vs. 9.8%). The conclusions: DES was superior to a BMS with respect to safety and efficacy endpoints. Thus, in that editorial I asked a question, and added a codicil: “Nonetheless, with the supportive data from LEADERS-FREE, is it time to finally be rid of BMS on interventional shelves? With mounting evidence that even patients with high bleeding risk are better served with a DES than a BMS, and DAPT is only needed for 30 days, perhaps it is time to agree BMS are not needed any longer even for those patients that might have benefitted. But then again, there are those patients who steadfastly refuse to take DAPT, or cannot afford it.” I should have added: “And, arguably, are at high bleeding risk, or need surgery that cannot be delayed.”

At the European Society of Cardiology Congress held in Rome in August, two new trials were reported that shed further light, and perhaps some confusion, on the discussion of BMS vs. DES. The first, and superficially most contrary to the pro-DES argument is the NORSTENT Trial (1). NORSTENT compared long term effects of a new generation DES with a contemporary BMS in more than 9,000 patients with stable or unstable angina and followed the outcomes for 6 years. The major endpoints were mortality, morbidity, and target vessel revascularization. The short version of the results is that there was no difference in the primary endpoint (death or non-fatal myocardial infarction) between the two groups. Death from any cause and nonfatal myocardial infarction was almost identical: 16.6% in the DES vs. 17.1% in the BMS patients. Multiple adjustments for baseline differences (e.g. smoking status, hypertension, history of myocardial infarction, target-lesion type, total stent length, lesion and procedural characteristics) yielded the same results. However, at 6 years the DES group had fewer revascularization procedures (driven by target lesion revascularization) at 16.5% vs. 19.8%. Interestingly, rates of stent thrombosis were extremely low at 0.8% and 1.2% in the DES and BMS groups respectively.

What does this study add to the discussion of DES vs. BMS? At first glance it might appear to support the notion that BMS and DES are alike, so why not go with the less expensive BMS? But I do not think that is correct. Coronary stents were developed to counter the complications of “plain old balloon angioplasty” (POBA). Though primitive, the first stents actually did a good job in avoiding urgent/emergent coronary surgery that was so often needed after a POBA. It was stents that finally erased the concept of “surgical standby.” As stents improved in design they were routinely used to enhance the results of POBA, cover local coronary dissections, and help reverse sudden coronary occlusions. In doing so, stents actually further damage the vessel media, enhancing smooth muscle cell proliferation and restenosis. DES then helped solve that problem by inhibiting cellular ingrowth. Thus, it comes as no surprise that the mortality and MI outcomes of DES vs. BMS are similar. Both DES and BMS perform admirably in the short setting of a PCI. It’s the long term differences that result in DES superiority. Restenosis, resulting in need for repeat revascularization is the downside of BMS. It is a slow process and mostly causes recurrent symptoms before acute MI and/or death. The NORSTENT Trial confirms that notion, and further supports the fact that need for vessel revascularization is more common with BMS. Rather than raising the question that we ought to reconsider BMS when stenting, the data actually support the use of DES to avoid repeat procedures and more healthcare resources. If BMS and DES were equal in cost and both could be used in patients with high bleeding risk, I bet that almost all stenting procedures would/should be done with DES.

But this is not an all-or-none argument. BMS might be just fine for large vessel PCI since intimal ingrowth is not so much a risk. For patients with bleeding risk, need for urgent surgery, or those in atrial fibrillation where triple therapy clearly increases bleeding risk, the argument for BMS vs. DES simply does not have enough data support to favor one over the other, though BMS will have a higher need for repeat revascularization. To complicate the argument further, DES do have slower endothelialization rates than BMS and therefore a low, but real late thrombosis risk. So the discussion continues, but the argument in favor of continuing to use BMS is steadily losing ground. BMS are a minority player, and will continue to be so.

To further bolster the pro-DES argument, the BASKET-SAVAGE Trial, also presented at ESC showed that DES are clearly superior to BMS in PCI of saphenous vein grafts (SVG). The randomized BASKET-SAVAGE Trial was to include 240 patients with SVG disease. The trial was stopped at 173 patients. At 12 months major adverse cardiac events had occurred in 18% of BMS vs. 2.3% of DES patients. At 3 years 30% of BMS patients had a major cardiac event, compared to 12.4% of DES patients (the outcome driven by target vessel revascularization, since cardiac deaths were similar in both groups). The trial is a small one, and the devices studied are no longer in use, making sweeping statements unrealistic, but the large differences in the DES and BMS groups do appear to strongly favor DES in SVG interventions. Other trials are currently underway to compare DES and BMS in SVG, but of note is that DES for SVG interventions are already a Class 1A recommendation in ESC guidelines.

So where does the argument stand? If we only had BMS and no DES, interventional cardiology would be in a bad place. We would indeed use antiplatelet agents for a shorter period of time, but at the cost of a lot more revascularization procedures. If we only had DES and no BMS, we would also be decreasing the length of antiplatelet use. We would also know that in the long term revascularization procedures would be fewer. It would be pretty much business as usual (and as most of us are currently practicing). Add to that a final question: “If they were the same price, would we really miss not having BMS? I doubt it.

Read the full September/October issue of CardioSource WorldNews Interventions at ACC.org/CSWNI

Keywords: CardioSource WorldNews Interventions, Blood Platelets, Drug-Eluting Stents, Hemorrhage, Metals, Myocardial Infarction, Polymers, Stents, Thrombosis

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