Bare Metal Stents: No Longer Passé?

Urgent coronary reperfusion unequivocally saves lives in the setting of acute coronary syndromes, however for most patients, the goal of percutaneous coronary intervention remains the control of anginal symptoms.^1,2 As a standalone procedure, balloon angioplasty is associated with relatively high rates of acute vessel closure and late restenosis.³ These complications are reduced with the use of bare metal stents deployed at high pressure and adjuvant dual antiplatelet therapy.^4–6 While bare metal stents effectively reduce the need for repeat revascularization compared to balloon angioplasty, they have not been shown to decrease the incidence of death or myocardial infarction.⁶ Drug-eluting stents were designed to further reduce the nagging problem of neointimal hyperplasia that still limits a proportion of bare metal stent procedures. The first reports of drug-eluting stents documented the virtual elimination of restenosis and generated intense enthusiasm for their use.^7–9 Drug-eluting stents were hailed as landmark therapy by the cardiology community. Furthermore, patients expected to receive these highly-touted devices, further fueling their widespread acceptance and use. Despite the reduction in restenosis afforded by drug-eluting stents, they have also not been shown to reduce outcomes of death or myocardial infarction.¹⁰ More than 85% of percutaneous coronary interventions in the United States are now performed with drug-eluting stents.¹¹ The wide and unrestricted use of drug-eluting stents is interesting since the pivotal clinical trials that introduced them were largely performed in stable patients with simple, de novo lesions.^8,9 Unstable patients with acute coronary syndromes or cardiogenic shock were usually excluded from trial participation. Also underrepresented in these trials were patients with in-stent restenosis, saphenous vein graft disease, bifurcation lesions, left main disease, left ventricular systolic dysfunction, renal failure and multiple lesions that would require long total stent length. As trials confirmed the efficacy of drug-eluting stents, recent reports have documented an association with late drug-eluting stent thrombosis when antiplatelet therapy is discontinued. This is a serious and often catastrophic complication that frequently results in myocardial infarction or death.¹² Given that drug-eluting stents have not been proven to reduce “hard” outcomes, increased vigilance should be given to their safety profile. A meta-analysis of 14 randomized clinical trials in nearly 7,000 patients revealed that drug eluting stents increase the risk for late thrombosis 4- to 5-fold compared to bare metal stents.¹³ In this report, the median time for late drug eluting stent thrombosis was 18 months, compared to a median time of 3.5 months for bare metal stents. This report is especially concerning given the relatively simple lesions and stable patient population included in the analysis. Real-world experience with drug-eluting stents also documents their tendency towards late thrombosis a year or more after implantation. While this complication is infrequent, it is associated with high morbidity and mortality.^12,14,15 Recently, renal failure, bifurcation lesions and in-stent restenosis have been identified to be predictors of late drug-eluting stent thrombosis. Since these characteristics were relatively understudied in the pivotal clinical trials, the actual risk for late drug-eluting stent thrombosis with their unrestricted use in the real world could be even more pronounced. Additionally, among patients who receive a drug-eluting stent in the setting of an acute myocardial infarction, clopidogrel is often prematurely discontinued, which markedly increases subsequent mortality.¹⁶ With this backdrop in mind, Kandzari and colleagues are to be applauded for a significant and timely contribution to the literature.¹⁷ They examined the 1-year incidence of death and target vessel revascularization among an unselected group of individuals who had received bare metal stents. Individuals were divided into 3 groups based on when they had received their stent. The earliest group was revascularized from 1994 to 1996, the intermediate group from 1997 to 1999, and the latest group from 2000 to 2002. Approximately one-fourth of the patients were treated in the setting of an acute myocardial infarction. One-year follow up among the nearly 6,000 studied individuals revealed an overall target vessel revascularization of 11.4%, with a 4.9% incidence of death. There was no trend in survival over the extent of follow up, however the adjusted rate of target vessel revascularization decreased over time to 9.3% from 2000 to 2002. This low rate of revascularization appears remarkable, although it should not be unexpected. With the increased popularity in drug-eluting stents, it was easy for improvements in bare metal stent technology to become overshadowed. Research has shown a pronounced reduction in restenosis and need for revascularization with the use of a thin-strut bare metal stent (i.e., 50 mcg) compared to a thick-strut stent (i.e., 140 mcg).¹⁸ Moreover, in many of the pivotal drug-eluting stent trials, thick-strut bare metal stents were used for the control group, which may have overestimated the beneficial effects of drug-eluting stents.¹⁹ This research complements the work of Ellis and colleagues, who similarly to the analysis of Kandzari and colleagues, documented low target vessel revascularization, and additionally identified specific patient subsets at low risk of 9-month revascularization after bare metal stent implantation.²⁰ For example, a nondiabetic patient with a short, de novo, nonbifurcation lesion in a large vessel would be expected to have a very low risk of restenosis and little to gain from the use of a drug-eluting stent. These findings should encourage the interventional cardiology community to assess a patient’s risk for restenosis prior to stent implantation. For those at low risk for restenosis, the use of a thin-strut bare metal stent should be considered a reasonable alternative or even superior alternative to a drug-eluting stent. Additionally, noncompliant patients and those with an anticipated need for surgery that would require the interruption of antiplatelet therapy should also temper enthusiasm for the use of drug-eluting stents. With a new-found appreciation for low revascularization after bare metal stents and concerns of late thrombosis with drug-eluting stents, the use of bare metal stents should no longer be considered passé. In fact, the use of bare metal stents is likely to become more in vogue.

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