The use of stents in primary and rescue percutaneous coronary intervention (PCI) is superior to balloon angioplasty, with lower rates of repeat revascularization and lower mortality1,2. Drug-eluting stents (DES) have been shown to be safe and more effective than bare-metal stents (BMS) in reducing restenosis and the frequency of repeat interventions in patients undergoing elective PCI3,4. However, there are conflicting results regarding the efficacy of DES as compared to BMS in the setting of primary PCI for ST-elevation acute myocardial infarction (STEMI). In particular, late stent thrombosis due to delayed endothelization and malapposition after DES implantation raises safety concerns, since there are studies suggesting that DES are associated with an increased rate of this event compared to BMS5,6.

The aim of this study was to compare the clinical outcomes of patients presenting with STEMI treated with DES or BMS as part of primary PCI.

The data from this registry show that DES are safe in the setting of STEMI, although it demonstrates no benefit in efficacy, since there was no significant difference in the incidence of the primary outcome of death, MI or TLR at one year and during the entire follow-up.

The incidence of stent thrombosis and the angiographic and electrocardiographic variables that were assessed showed that the procedure results were similar regardless of type of stent. Although the groups were well matched in most clinical and angiographic characteristics, patients in the DES group tended to be younger and had a greater incidence of the LAD as the infarct-related vessel.

Results from registries and randomized trials have shown conflicting results. The main proven benefit of DES over BMS is a reduction in restenosis, which may be outweighed by the need for prolonged dual antiplatelet therapy and the potentially higher risk of very late stent thrombosis. Recent robust data from the HORIZONS-AMI trial demonstrate that in patients with STEMI undergoing primary angioplasty, implantation of paclitaxel-eluting stents, compared with bare-metal stents, significantly reduced angiographic evidence of restenosis and ischemia-driven repeat revascularization procedures, with no differences in death, stent thrombosis, reinfarction or stroke7. However, the PASSION trial, which compared 619 patients treated with paclitaxel-eluting stents or BMS in the setting of STEMI, found no significant difference in death, reinfarction, stent thrombosis or TLR at one year8, which is in line with the results of our study. Trials that randomized patients to sirolimus-eluting stents or BMS, such as STRATEGY, TYPHOON and SESAMI, have different results from our registry, showing a lower rate of repeat revascularization procedures, but no difference in other clinical outcomes9–11. It should be emphasized, however, that these studies on sirolimus-eluting stents all had angiographic follow-up, which may have biased the operator to intervene in the BMS group.

Late stent thrombosis is a matter of concern when DES are used in patients with STEMI, since there are published data indicating that late healing and re-endothelization may be impaired when DES are implanted at the site of a ruptured plaque, and this may lead to late stent thrombosis12. In fact, incomplete expansion and undersizing may occur more often in the setting of STEMI because of the presence of coronary thrombus. This may be more frequently associated with DES, where there is little tissue in-growth, compared with BMS, where more extensive tissue in-growth occurs and may prevent malapposition. The MISSION intervention study showed that acquired stent malapposition at 9 months was more common with DES than with BMS (25% vs 5%, p<0.001) 13. Our study found no difference in stent thrombosis between DES and BMS, which is similar to the results from several randomized trials, as shown by De Luca et al. in a recent meta-analysis of randomized trials on the efficacy and safety of DES in STEMI (1.6% in DES vs 2.2% in BMS, p=NS, at 12-month follow-up) 14. The incidence of this event in our registry is higher than in this meta-analysis but is similar to the results of HORIZONS-AMI and TYPHOON7,10. In our study most stent thromboses occurred within the first days after STEMI, which suggests that they were related to the procedure rather than the type of stent. The only two cases of late stent thrombosis were observed in the BMS group, which is surprising given the concern regarding this event and the use of DES.

A parallel finding of our study concerns the protective effect of glycoprotein IIb/IIIa inhibitors on the occurrence of death, MI and TLR in this population. Randomized trials have shown conflicting results regarding the use of glycoprotein IIb/IIIa inhibitors in this setting. A previous meta-analysis showed significant benefits in mortality and reinfarction15, but more recent large randomized trials with the adjunctive administration of clopidogrel (BRAVE-3 and HORIZONS trials) failed to demonstrate the same results16,17. One striking feature is the proportion of patients (over 70%) undergoing this therapy, in contrast to the data in the Portuguese Registry of Acute Coronary Syndromes, in which only 20% of patients with STEMI were treated with glycoprotein IIb/IIIa inhibitors18.

Our study has the limitations of a single-center registry and as such the outcomes may be influenced by confounders. For instance the larger stent diameter in the BMS group may mean that these patients had a lower risk of restenosis than the patients in the DES group, which would underestimate the benefit of DES use. Moreover, the results are based on a relatively small patient cohort and may lack power. Nevertheless the study provides outcomes of a cohort of patients with STEMI treated with BMS or DES and in addition to having a long follow-up, it takes into account important reperfusion variables such as TIMI frame count, myocardial blush grade and ECG ST-segment elevation resolution.

This study found no differences in major adverse cardiovascular events or angiographic outcomes after treatment with DES or BMS in this group of patients with STEMI, which validates the safety of coated stents but shows no improvement in efficacy.

Concomitant administration of glycoprotein IIb/IIIa inhibitors still confers protection in this setting.

The authors declare they have no conflicts of interest.