Two-Year HORIZONS-AMI Data Published

April 26, 2011—George D. Dangas, MD, et al published findings from the HORIZONS-AMI (Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction) trial in Circulation (2011;123:1745–1756).

The HORIZONS-AMI investigators concluded that stent thrombosis is not uncommon within the first 2 years after primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) and occurs with similar frequency in patients receiving drug-eluting stents versus bare-metal stents and bivalirudin alone versus heparin plus a glycoprotein IIb/IIIa inhibitor (GPI). Optimizing adjunct pharmacology, including early antithrombin therapy preloading with a potent antiplatelet therapy, may further reduce stent thrombosis in STEMI, the investigators advised.

As detailed in Circulation, the background of the HORIZONS-AMI study is that concerns persist regarding the risk of stent thrombosis in the setting of primary PCI for STEMI. The trial included 3,602 patients with STEMI undergoing primary PCI who were randomized to heparin plus a GPI (n = 1,802) versus bivalirudin monotherapy (n = 1,800). Stents were implanted in 3,202 patients including 2,261 who received drug-eluting stents and 861 who received only bare-metal stents.

The investigators reported that definite or probable stent thrombosis within 2 years occurred in 137 patients (4.4%), including 28 acute events (0.9%), 49 subacute events (1.6%), 32 late events (1%), and 33 very late events (1.1%). The 2-year cumulative rates of stent thrombosis were 4.4% with both drug-eluting stents and bare-metal stents (P = .98) and 4.3% versus 4.6% in patients randomized to bivalirudin monotherapy versus heparin plus a GPI, respectively (P = .73). Acute stent thrombosis occurred more frequently in patients assigned to bivalirudin compared with heparin plus a GPI (1.4% vs 0.3%; P < .001), whereas stent thrombosis after 24 hours occurred less frequently in patients with bivalirudin compared with heparin plus a GPI (2.8% vs 4.4%; P = .02). Prerandomization heparin and a 600-mg clopidogrel loading dose were independent predictors of reduced acute and subacute stent thrombosis, respectively.