Fondaparinux compared to enoxaparin in patients with acute coronary syndromes without ST-segment elevation: outcomes and treatment effect across different levels of risk.

Background: The OASIS-5 (Organization to Assess Strategies in Ischemic Syndromes-5) trial demonstrated that fondaparinux was noninferior to enoxaparin while reducing the risk of bleeding by 50%. The objectives of our study were to assess the effects of fondaparinux compared to enoxaparin in patients stratified by their Global Registry of Acute Coronary Events (GRACE) score and to examine the ability of the GRACE score to predict bleeding in patients with acute coronary syndromes (ACS).

Methods: We analyzed efficacy and safety according to the GRACE admission risk score.

Results: The impact of fondaparinux versus enoxaparin on the primary outcome of death, myocardial infarction, and refractory ischemia at 180 days was similar in the low-, intermediate-, and high-risk groups: 7.0% versus 7.7% (hazard ratio [HR] 0.90, 95% confidence interval [CI] 0.75-1.08), 10.2% versus 11.3% (HR 0.89, 95% CI 0.77-1.03), and 20.1% versus 21.1% (HR 0.95, 95% CI 0.85-1.06). Major bleeding rates were higher with increasing GRACE risk scores: 2.2%, 3.2%, and 4.1% in the low, intermediate, and high-risk groups. Six-month mortality was 2.2%, 4.2%, and 12.3% in the 3 groups. The risk of major bleeding was substantially lower with fondaparinux in all groups: 1.6% versus 2.9% (HR 0.55, 95% CI 0.39-0.77), 2.2% versus 4.1% (HR 0.53, 95% CI 0.40-0.70), 2.8% versus 5.5% (HR 0.50, 95% CI 0.38-0.64).

Conclusion: The GRACE score predicted both bleeding and mortality in patients with ACS. The efficacy and safety of fondaparinux were consistent in all risk groups supporting its use in a broad range of ACS patients.