<h2>Summary</h2><h3>Background</h3> Primary results of the HORIZONS-AMI trial have been previously reported. In this final report, we aimed to assess 3-year outcomes. <h3>Methods</h3> HORIZONS-AMI was a prospective, open-label, randomised trial undertaken at 123 institutions in 11 countries. Patients aged 18 years or older were eligible for enrolment if they had ST-segment elevation myocardial infarction (STEMI), presented within 12 h after onset of symptoms, and were undergoing primary percutaneous coronary intervention. By use of a computerised interactive voice response system, we randomly allocated patients 1:1 to receive bivalirudin or heparin plus a glycoprotein IIb/IIIa inhibitor (GPI; pharmacological randomisation; stratified by previous and expected drug use and study site) and, if eligible, randomly allocated 3:1 to receive a paclitaxel-eluting stent or a bare metal stent (stent randomisation; stratified by pharmacological group assignment, diabetes mellitus status, lesion length, and study site). We produced Kaplan-Meier estimates of major adverse cardiovascular events at 3 years by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00433966. <h3>Findings</h3> Compared with 1802 patients allocated to receive heparin plus a GPI, 1800 patients allocated to bivalirudin monotherapy had lower rates of all-cause mortality (5·9% <i>vs</i> 7·7%, difference −1·9% [−3·5 to −0·2], HR 0·75 [0·58–0·97]; p=0·03), cardiac mortality (2·9% <i>vs</i> 5·1%, −2·2% [−3·5 to −0·9], 0·56 [0·40–0·80]; p=0·001), reinfarction (6·2% <i>vs</i> 8·2%, −1·9% [−3·7 to −0·2], 0·76 [0·59–0·99]; p=0·04), and major bleeding not related to bypass graft surgery (6·9% <i>vs</i> 10·5%, −3·6% [−5·5 to −1·7], 0·64 [0·51–0·80]; p=0·0001) at 3 years, with no significant differences in ischaemia-driven target vessel revascularisation, stent thrombosis, or composite adverse events. Compared with 749 patients who received a bare-metal stent, 2257 patients who received a paclitaxel-eluting stent had lower rates of ischaemia-driven target lesion revascularisation (9·4% <i>vs</i> 15·1%, −5·7% [−8·6 to −2·7], 0·60 [0·48–0·76]; p<0·0001) after 3 years, with no significant differences in the rates of death, reinfarction, stroke or stent thrombosis. Stent thrombosis was high (≥4·5%) in both groups. <h3>Interpretation</h3> The effectiveness and safety of bivalirudin monotherapy and paclitaxel-eluting stenting are sustained at 3 years for patients with STEMI undergoing primary percutaneous coronary intervention. <h3>Funding</h3> Boston Scientific and The Medicines Company.

Heparin plus a glycoprotein IIb/IIIa inhibitor versus bivalirudin monotherapy and paclitaxel-eluting stents versus bare-metal stents in acute myocardial infarction (HORIZONS-AMI): final 3-year results from a multicentre, randomised controlled trial