Effect of switching antithrombin agents for primary angioplasty in acute myocardial infarction: the HORIZONS-SWITCH analysis

Objectives: We investigated the outcomes of switching to bivalirudin after initial administration of heparin in patients with acute ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention.

Background: Unfractionated heparin (UFH) is frequently administered early in ST-segment elevation myocardial infarction. Whether the benefits of bivalirudin documented in the HORIZONS-AMI (Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction) trial persist in patients previously administered UFH is unknown.

Methods: We analyzed the outcomes of the 2,357 patients from HORIZONS-AMI treated with UFH before enrollment according to their subsequent randomization to bivalirudin (switch group, n = 1,178) or UFH plus a glycoprotein IIb/IIIa inhibitor (control group, n = 1,179).

Results: At 30 days, major bleeding occurred in 7.6% of the switch group versus 12.3% of the control group (p = 0.0001). Switch patients had lower 30-day rates of cardiac mortality (1.6% vs. 2.9%, p = 0.04). At 2-year follow-up, switch patients experienced lower rates of major bleeding (8.4% vs. 13.0%, p = 0.0003), cardiac mortality (2.3% vs. 3.8%, p = 0.04), and reinfarction (4.0% vs. 7.1%, p = 0.0002). Two-year rates of definite/probable stent thrombosis were similar in switch and control patients (3.1% vs. 4.3%, p = 0.17).

Conclusions: In ST-segment elevation myocardial infarction patients who receive early treatment with UFH, switching to bivalirudin before primary percutaneous coronary intervention results in reduced rates of major bleeding and improved early and late cardiac survival.