Frequency and predictors of stent thrombosis after percutaneous coronary intervention in acute myocardial infarction.

Abstract

Concerns persist regarding the risk of stent thrombosis in the setting of primary percutaneous coronary intervention for ST-segment elevation myocardial infarction. The Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial included 3602 patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention who were randomized to heparin plus a glycoprotein IIb/IIIa inhibitor (GPI) (n=1802) versus bivalirudin monotherapy (n=1800). Stents were implanted in 3202 patients, including 2261 who received drug-eluting stents and 861 who received only bare metal stents. 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 (1.0%), 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=0.98) and 4.3% versus 4.6% in patients randomized to bivalirudin monotherapy versus heparin plus a GPI, respectively (P=0.73). Acute stent thrombosis occurred more frequently in patients assigned to bivalirudin compared with heparin plus a GPI (1.4% versus 0.3%; P<0.001), whereas stent thrombosis after 24 hours occurred less frequently in patients with bivalirudin compared with heparin plus a GPI (2.8% versus 4.4%; P=0.02). Pre-randomization heparin and a 600-mg clopidogrel loading dose were independent predictors of reduced acute and subacute stent thrombosis, respectively. Stent thrombosis is not uncommon within the first 2 years after primary percutaneous coronary intervention in ST-segment elevation myocardial infarction, and occurs with similar frequency in patients receiving drug-eluting stents versus bare metal stents and bivalirudin alone versus heparin plus a GPI. Optimizing adjunct pharmacology including early antithrombin therapy preloading with a potent antiplatelet therapy may further reduce stent thrombosis in ST-segment elevation myocardial infarction.