Drug-Eluting Versus Bare-Metal Stents

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DR. COLOMBO: I use drug-eluting stents in over 90% of stable patients; I use bare-metal stents in at least 60% of patients with STEMI and in some patients with acute coronary syndrome. I would summarize that I use drug-eluting stents in at least 80% of all patients undergoing PCI.

DR. KEREIAKES: I use drug-eluting stents in more than 90% of stable patients. I would consider putting a bare-metal stent in somebody who needs major surgery within 3 months, and if the referring cardiologist is demanding implantation of a bare-metal stent. With regard to STEMI, I differ from Dr. Colombo. I think 90% of the time I would use a drug-eluting stent because all of the multiple randomized trials and meta-analyses that have been done, with follow-up periods of up to 3 to 5 years, demonstrate a highly significant reduction in target vessel revascularization with no penalty. By that I mean there is no increase in stent thrombosis or MI with drug-eluting stents vs bare-metal stents.

DR. KIRTANE: I also use drug-eluting stents for the great majority of our patients. Our patient mix (in Washington Heights, New York) is a little different, so I’d say for electives, it’s probably 70% to 80% drug-eluting stents, but the decision-making hinges on adherence and then, as Dr. Kereiakes said, surgery. This typically only applies to upcoming surgery within the next 3 months, because I think if you can delay the surgery for 3 months, with some of the early discontinuation data, you may still be able to implant the drug-eluting stent.

DR. COLOMBO: There is no question about the benefit of drug-eluting stents in some patients with STEMI. These patients are diabetics or any patient with a lesion on a vessel smaller than 3 mm in diameter or requiring a stent longer than 15/20 mm.

DR. STONE: We actually demonstrated this in a substudy of the Harmonizing Outcomes with RevasculariZatiON and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial.15 We found that the 2-year rates of target-lesion revascularization with bare-metal stents and drug-eluting stents were similar in nondiabetic MI patients with a large reference vessel diameter and a short culprit lesion. However, the target-lesion revascularization rates with bare-metal stents were increased significantly in patients with 1 or more of these 3 risk factors, and such patients had an incrementally greater benefit with drug-eluting stents in terms of absolute reduction of target lesion revascularization. This holds true in patients with non-STEMI and stable coronary artery disease as well. So, this is a very reasonable approach for all patients, especially those with STEMI in whom target lesion revascularization rates tend to be lower because of an infarcted myocardium that is less likely to produce symptoms of angina if restenosis occurs.

Dr. Kirtane, clearly the current-generation, drug-eluting stents have improved outcomes for patients, have reduced stent thrombosis rates, may have reduced MI rates, conferred long-term freedom from ischemia, etc. Most of the trials that we’re founding our clinical decisions on, such as the COURAGE trial comparing PCI to medical therapy in stable coronary artery disease and the SYNergy Between PCI With TAXUS and Cardiac Surgery (SYNTAX)16 and Future Revascularization Evaluation in Patients With Diabetes Mellitus: Optimal Management of Multivessel Disease (FREEDOM) trials17 comparing PCI to surgery in complex coronary disease, were performed with either bare-metal stents or first-generation, drug-eluting stents. How would the availability of the current-generation, drug-eluting stents have affected the outcomes of these trials and therefore our decision making?

DR. KIRTANE: I think that’s a critically important question. Particularly regarding COURAGE, SYNTAX, and even the FREEDOM trial, this is very relevant. In terms of the safety endpoints, in the SYNTAX trial with a first-generation, drug-eluting stent, there was a stent thrombosis rate of over 10% at 5 years. Similarly, the PCI-related durability of symptom relief and quality-of-life benefits were called into question in COURAGE, but the use of drug-eluting stents in COURAGE would have likely changed those findings dramatically. It is difficult to deal with the fact that technology advances faster than the trials can enroll patients and subsequently be published, so it seems as though we’re always communicating or commenting on trials that have been performed in a different era. I personally think that this is important for all of us to realize, but it’s more important to communicate this to noninterventionalists. As interventionalists, we all know these data because we’re exposed to it every day, but for noninterventionalists, these may be novel concepts.

DR. STONE: Finally, I would like to hear some future perspectives from both Drs. Kereiakes and Colombo. Do you anticipate a fourth revolution in drug-eluting stent technology as we move from durable polymers to bioresorbable polymers to truly polymer-free, metallic, drug-eluting stents and finally to fully bioresorbable vascular scaffolds? Alternatively, are the changes likely to be small and iterative or even difficult to demonstrate given the excellent outcomes with today’s devices?

DR. COLOMBO: Stents without polymer have a rationale. Dr. Kereiakes, very correctly, said that we need to prove that no polymer is superior to a fluorinated polymer in terms of thrombosis. This is an open field. I will not be surprised to see no clear advantage between no polymer vs “special polymer.” But let’s be optimistic and believe that we can go lower in terms of thrombosis. To move forward, I would like to say that bioabsorbable vascular scaffolds are a very exciting concept. I will vote for “no more metal in the coronary arteries.”

DR. STONE: In support of your belief, even with our best metallic drug-eluting stents, our patients still experience a 1.5% to 2.5% annual rate of adverse ischemic events related to the target lesion that keep occurring after 1 year, when healing is supposed to be stable, all the way up through (at least) 5 years. Dr. Kereiakes, you and I are leading one of the first US initiatives for a fully bioresorbable vascular scaffold (with Steve Ellis). How optimistic are you that we may further improve long-term outcomes for patients with coronary disease by using this novel device?

DR. KEREIAKES: I think we both share the optimism. Most of the trial designs for evaluating novel stent designs are going to demonstrate non-inferiority when compared to the “best-in-class” EES at 1 year. Beyond that point in time, the potential benefits of a completely bioresorbable platform, including the capacity for adaptive remodeling, the ability to accommodate atherosclerosis, the maintenance of autoregulation and normal microvascular endothelial function, and the potential to eliminate any nidus for neo-atherosclerosis, will be greater than either metal platform drug-eluting stents or bare-metal stents. This is the promise, Dr. Stone, but the real challenge will be to prove it. We need to look at landmark analyses in late follow-up to prove that a bioresorbable scaffold indeed provides material benefit with respect to reduction in death, MI, and repeat revascularization. Wouldn’t you agree?

DR. STONE: I would agree with you fully. We’re just beginning a 5-year clinical trial program with thousands of patients (the ABSORB clinical trials) to hopefully demonstrate whether this is true.

This has been an extraordinary discussion from 3 real experts in this field. If I were to summarize for the reader, I would say we’ve come a long way since 1977, when balloon angioplasty was introduced for the treatment of discrete proximal coronary stenosis, to the takeover of bare-metal stents, to the widespread adoption of first-generation and now second- and third-generation, drug-eluting stents. This evolution has translated into dramatic improvements in event-free survival for our patients. We’ve gone from stent thrombosis rates of >10% within the first 30 days to <0.5% within 30 days in most series with a very small incremental increase in stent thrombosis over time thereafter. We’ve reduced restenosis from as high as 50% or greater after balloon angioplasty down to approximately 10% or so after implantation of the best drug-eluting stents. These changes have translated into marked improvements in freedom from angina, exertional dyspnea, requirement for medications, rehospitalization, and repeat procedures. The link between ischemia and death/MI suggests that freedom from restenosis may translate into improved survival and MI-free survival. A large ongoing trial is now underway in an attempt to prove this within the framework of a randomized investigation.

Nonetheless, even with the best drug-eluting stents, there are still concerns regarding increased risk of late stent thrombosis compared with bare-metal stents, which does necessitate a prolonged duration of DAPT. Taking both benefits and risks into account, the appropriate duration of DAPT, whether that is 3, 6, or ≥12 months, is the subject of current ongoing large-scale randomized trials. One must consider the excellent outcomes with current drug-eluting stent technology when making clinical decisions regarding how to treat patients with obstructive coronary disease while also considering the alternatives of medical therapy or surgery. In this regard, many of the best clinical trials we have are already out of date.

Finally, all 4 of us are extremely optimistic about the future. We are in the midst of an unparalleled era of improving biotechnology, and drug-eluting stents are evolving. Metallic stent designs continue to improve, the amount of polymer (whether durable or bioresorbable) will continue to diminish or disappear, and we are well on the way toward demonstrating real clinical benefits of a fully bioresorbable vascular scaffold that can restore the native coronary artery back to its pristine state once the obstructive lesion has been treated. Adjunct pharmacology with enhanced efficacy and safety is being developed as well, and we are learning which patients need more or less potent antiplatelet and antithrombotic agents. We are entering the era of personalized medicine, and it is possible that genetic profiling may lead the way to smarter decision making. All of this is occurring on the background of more effective “optimal” medical therapy and risk-factor modification for primary and secondary prevention.

With those closing comments I’d like to thank Drs. Colombo, Kereiakes and Kirtane, who are truly 3 of the great physicians in this field. Thank you very much.