Can the restenosis benefit of drug-eluting and bare-metal stents be predicted?

Corresponding Author:

Carlo Briguori
Green Lane Cardiovascular Service
Auckland City Hospital Park Road
Auckland, New Zealand
E-mail:carlobriguori@clinicamediterranea.it

Abstract

Keywords

coronary intervention, outcome, predictors, restenosis, stent

Drug-eluting stents (DES) reduce restenosis rates and improve outcomes for patients with coronary artery disease treated with percutaneous coronary intervention (PCI) [1–3]. Concerns have been raised over the higher risk of stent thrombosis (ST), especially with the firstgeneration DES [4–6]. The restricted duration of dual antiplatelet therapy (DAT; less than 6 months) in early trials has been associated with the reported increased risk of death [7]. This forced physicians to prolong DAT for at least 12 months. Data from registries and meta-analyses have indicated that there is no difference in the risk of early (<30 days) and late (>30 days, <365 days) ST between DES and bare-metal stents (BMS), but an excessive risk emerges after 1 year of follow-up (very late ST) [3,6,8,9]. DAT with clopidogrel and aspirin substantially reduces the risk of ST. However, a low efficacy of antiplatelet therapy has been reported due to:

▪▪ Low response to clopidogrel;

▪▪ Poor patient compliance [10–12].

The need for nonthrombogenic or safer stents has caused the development of the secondgeneration DES, where much more attention has been paid to the polymer and the kinetics of drug release. Lately, the stent platform has experienced a renewed interest [13,14].

In order to clarify whether DES should be liberally implanted or, on the contrary, they should be selected for a subgroup of patients, Yeh et al. developed and validated a model to predict target vessel revascularization (TVR) [15]. In a large statewide registry (National Cardiovascular Data Registry) of 27,107 patients undergoing PCI, Yeh et al. found that TVR at 1 year occurred in 6.7% of patients treated with DES and 11% of patients treated with BMS. The absolute TVR reductions associated with DES use ranged from 1.2 to 15.9%, with an interquartile range of 3.5–6.3%. The predicted number needed to treat (NNT) to prevent one TVR with DES compared with BMS ranged from six to 80 patients, depending on the clinical and angiographic characteristics. Similar results were observed for the nonangiographic model, with the NNT ranging from eight to 61 patients. The proposed model predicting TVR risk included only 3 factors: diabetes mellitus, lesion/stent length and vessel/stent diameter. This model provides the opportunity to prospectively indentify and use DES in patients who stand to derive greater benefit from DES, while considering BMS in patients with low anticipated benefit. When the risk of restenosis with BMS is ≤10%, the NNT exceeds 25. Prior economic analyses have suggested that a TVR rate with BMS of <11% is associated with an increase in society-based costs of more than US$10,000 to prevent one repeat procedure and would not be considered a cost–effective use of DES [16]. In the present study, >45% of patients undergoing PCI had a predicted rate of restenosis with BMS that was less than this threshold, 78.6% of whom received DES. This result should be analyzed in the context of the risk for bleeding associated with prolonged DAT and ST. Although this model may help physicians in stent selection, we should highlight some important aspects:

▪▪DES and BMS in this study have been analyzed together (as a group). However, several data support the potential differences between different BMS [13] and DES [6,17,18]. In particular, second-generation DES showed a strong antirestenotic power and a low risk of ST [19,20]. Studies performed with optical coherence tomography suggest the extent and time for re-endothelialization is quite different between first- and second-generation DES [21];

▪▪ Stent implantation technique has an important role. Recent data suggest that intravascular ultrasound-guided stent implantation allows operators to achieve a larger final minimal lumen diameter [22];

▪▪DAT has an important role in preventing ST and future adverse cardiac events after PCI. Several studies have demonstrated that a proportion of patients are low-responsive to clopidogrel, implying a high on-treatment residual platelet reactivity [23]. This high residual platelet reactivity has been associated with a higher rate of ST. The availability of point-of-care tools and new drugs may impact future approaches in DAT in patients after PCI [23].

Financial & competing interests disclosure

The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Executive summary

▪▪ Although drug-eluting stents (DES) are more effective than bare-metal stent (BMS) in reducing restenosis rate, there is the need for a prolonged dual antiplatelet therapy.

▪▪ Furthermore, concerns have been raised on the higher risk of stent thrombosis after DES implantation.

▪▪ Debate exists whether DES should be used liberally or, on the contrary, they should be implanted only in patients at high risk for restenosis with BMS. This may have important clinical and economic impacts. Indeed, DES are more expensive than BMS.

▪▪ Yeh et al. propose a model predicting target vessel revascularization risk, which include only 3 factors: diabetes mellitus, lesion/stent length and vessel/stent diameter. In this model, a target vessel revascularization rate with BMS of <11% is associated with an increase in society-based costs of more than US$10,000 to prevent one repeat procedure and would not be considered a cost-effective use of DES.

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