Here's some real world experience reported from a Swedish database:
Design, Setting, and Patients Prospective multicenter cohort study from the Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies registry involving 40 616 consecutive patients with NSTEMI who received fondaparinux or LMWH between September 1, 2006, through June 30, 2010, with the last follow-up on December 31, 2010.
Exposures In-hospital treatment with fondaparinux or LMWH during the hospital stay...
Results In total, 14 791 patients (36.4%) were treated with fondaparinux and 25 825 (63.6%) with LMWH. One hundred sixty-five patients (1.1%) in the fondaparinux group vs 461 patients (1.8%) in the LMWH group experienced in-hospital bleeding events (adjusted odds ratio [OR], 0.54; 95% CI, 0.42-0.70). A total of 394 patients (2.7%) in the fondaparinux group died while in the hospital vs 1022 (4.0%) in the LMWH group (adjusted OR, 0.75; 95% CI, 0.63-0.89). The differences in major bleeding events and mortality between the 2 treatments were similar at 30 and 180 days. There were no significant differences in the number of recurrent MI and stroke events at 30 or 180 days among the 2 treatment groups.
These findings are somewhat similar to those of OASIS 5 which I referenced here.
It would appear that the improved outcome was driven by a reduction in bleeding with fondaparinux. I think this relates to the fact that for acute coronary syndrome fondaparinux is administered in the same dose as is used for VTE prophylaxis rather than in a full therapeutic anticoagulation dose.