Enoxaparin versus heparin: the SYNERGY trial from an emergency medicine perspective

The SYNERGY (Superior Yield of the New strategy of Enoxaparin, Revascularisation, and GlYcoprotein inhibitors) trial, involving almost 10,000 patients, is a landmark cardiology study published in 2004. The study compared two anticoagulants used as part of a modern early invasive strategy involving angiographic triage of high-risk non-ST-elevation acute coronary syndrome patients. The trial as a whole showed similar efficacy between unfractionated heparin and enoxaparin. Regarding safety, two of the three in-hospital bleeding endpoints reported were similar between the two anticoagulants. Importantly, because of the high rate of pre-enrolment anticoagulant administration, many study participants required an anticoagulant change after randomisation. Thus, close attention is warranted to a prespecified subanalysis of >6000 patients who received 'consistent therapy'; that is, the same anticoagulant was administered pre- and post-enrolment based on intention to treat. In this large 'consistent therapy' cohort, the efficacy endpoint favoured enoxaparin and, as in the overall study population, two of the three reported bleeding endpoints were similar between the two anticoagulants. Finally, the rate of peri-procedural thrombotic complications that occurred during percutaneous coronary intervention was equal for both anticoagulants. Thus, since both anticoagulants have a similar efficacy and safety profile, then the simplicity of the enoxaparin regimen (i.e. no monitoring of activated partial thromboplastin time and easy dose calculation of 1 mg/kg subcutaneously) provides an important and desirable feature relevant to a busy emergency medicine practitioner.