In the OASIS-5 trial (Organzation to Assess Strategies in Acute Ischaemic Syndromes), fondaparinux was found to be non-inferior to enoxaparin for the primary outcome, but was noted to halve major bleeding, leading to a significant mortality reduction. However, a small but significant increase in catheter-related thromboses was also seen, therefore the FUTURA/OASIS-8 trial was set up to evaluate the safety of two-dose regimens of adjunctive intravenous unfractionated heparin during PCI in high-risk patients with non-ST segment elevation acute coronary syndromes initially treated with fondaparinux.

2026 patients were enrolled from February 2009 to March 2010. Patients received either low dose unfractionated heparin (50U/kg) or standard-dose unfractionated heparin (85U/kg), adjusted by blinded activated clotting time (ACT). The main outcome measure was a composite of major bleeding, minor bleeding, or major vascular access-site complications up to 48hrs after PCI.

The primary outcome measure occurred in 4.7% of the low-dose group vs 5.8% in the standard-dose group (p= .27). Minor bleeding rates were noted to be different (0.7% vs 1.7%; p= .04), however no difference in major bleeding rates was seen. Death, myocardial infarction, or target vessel revascularisation occurred in 4.5% in the low-dose group, compared to 2.9% in the standard dose group (p= .06). Catheter thrombus rates were low (0.5% vs 0.1%, p= .15), and therefore no statistically significant difference was seen.

Conclusions

In this trial, no significant benefit was seen from using low-dose unfractionated heparin as part of a two-dose regiment during high-risk PCI for acute coronary syndromes.

▶ FUTURA/OASIS-8 trial group, 2010. Low-dose versus standard-dose unfractionated heparin for percutaneous coronary intervention in acute coronary syndromes treated with fondaparinux. The FUTURA/OASIS-8 randomized trial. JAMA 2010. doi:10.1001/jama.2010.1320.