Aims: Compared with bare metal stents (BMS), early generation drug-eluting stents (DES) reduce the risk of revascularisation in patients with ST-elevation myocardial infarction (STEMI) at the expense of an increased risk of very late stent thrombosis (ST). Durable polymer coatings for controlled drug release have been identified as a potential trigger for these late adverse events and this has led to the development of newer generation DES with durable and biodegradable polymer surface coatings with improved biocompatibility. In a recent all-comers trial, biolimus-eluting stents with a biodegradable polymer surface coating were found to reduce the risk of very late ST by 80% compared with sirolimus-eluting stents with durable polymer, which also translated into a lower risk of cardiac death and myocardial infarction (MI) beyond one year. Methods and results:The multicentre COMFORTABLE AMI trial (NCT00962416) randomly assigned 1,161 patients to treatment with biolimus-eluting stents with biodegrable polymer and bare metal stents of otherwise identical design at 11 international sites. The primary endpoint is a composite of cardiac death, target-vessel MI and target lesion revascularisation at one year. Assuming a relative risk reduction of 40% in event rates of the primary endpoint in favour of biolimus-eluting stents with biodegradable polymer, 1,064 patients will provide 80% power to demonstrate superiority. Clinical follow-up will be continued through five years. Conclusions:The COMFORTABLE AMI trial will determine whether biolimus-eluting stents with biodegradable polymer are superior to bare metal stents of otherwise identical design. This is the first randomised controlled trial (RCT) investigating DES with a biodegradable polymer surface coating for drug release in the treatment of patients with STEMI.

Aims: Selective use of DES only in patients at higher risk of MACE is common practice, particularly in healthcare systems with a large premium payable for DES. We aimed to identify subgroups of patients in which the use of BMS in primary percutaneous coronary intervention (PPCI) for STEMI can still be justified.Methods and results: We performed a patient-level pooled analysis of COMFORTABLE AMI and EXAMINATION comparing contemporary DES with BMS in PPCI. A risk score was applied using three parameters: lesion length >15 mm, vessel size <3 mm, and diabetes mellitus. Individual data were available for 2,655 patients. The incidence of MACE at one year was incrementally higher in patients with risk scores of 1 or 2/3. MACE rates were lower in patients with a risk score 0 or 1 who were treated with DES (p=0.0073 and p=0.008). No difference in death or reinfarction was seen between DES and BMS in any group. There was a significant reduction in TLR with DES in all three groups.Conclusions: A score comprising vessel size, lesion length, and diabetes did not identify patients at low risk with equivalent or better results from BMS use. The results suggest that the practice of only selective use of DES in primary PCI should be discouraged. KEYWORDS• drug-eluting stents • primary angioplasty • STEMI