Efficacy and safety of prehospital administration of unfractionated heparin, enoxaparin or bivalirudin in patients undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction: Insights from the ORBI registry.

Background: Despite numerous studies in recent years, the best anticoagulant option for primary percutaneous coronary intervention (PCI) remains a matter of debate.

Aims: To compare in-hospital outcomes after prehospital administration of low-dose unfractionated heparin (UFH)±glycoprotein IIb/IIIa inhibitors (GPIs), enoxaparin±GPIs, or bivalirudin in patients undergoing primary PCI for ST-segment elevation myocardial infarction (STEMI).

Methods: A total of 1720 patients (median age 62.0 years, 79.2% male) who had been enrolled in a prospective registry and received an injectable anticoagulant in physician-staffed mobile intensive care units before primary PCI were included in the study. The main outcomes were in-hospital major adverse cardiovascular events (MACE) (a composite of all-cause mortality, non-fatal myocardial infarction, stroke or definite stent thrombosis) and in-hospital major bleeding (Bleeding academic research consortium type 3 or 5).

Results: UFH was administered in 420 (24.4%) patients, enoxaparin in 1163 (67.6%) patients and bivalirudin in 137 patients (8.0%). Rates of in-hospital MACE were 7.4% with UFH, 6.0% with enoxaparin and 6.6% with bivalirudin, with no significant differences between groups (P=0.628). In-hospital major bleeding occurred in 1.7% of patients on UFH, 1.4% on enoxaparin and 1.5% on bivalirudin (P=0.851). By multivariable analysis, the prehospital anticoagulant used was not an independent predictor of MACE or major bleeding.

Conclusion: In this prospective registry, there were no significant differences in the rates of in-hospital MACE or major bleeding after prehospital initiation of UFH, enoxaparin or bivalirudin in patients treated by primary PCI for STEMI.