While enoxaparin use during elective PCI has been associated with less major bleeding compared with UFH, they note, “The effect of enoxaparin may be different in the setting of fibrinolytic therapy, where procoagulant activity is increased.”
To compare the relative efficacy of enoxaparin and UFH in this setting, the team conducted a substudy of data from the TRANSFER-AMI study in which 946 high-risk STEMI patients received fibrinolysis and then were randomized to standard treatment or immediate coronary angiography. About half the patients received enoxaparin at the time of fibrinolytic therapy while the others were given UFH.
The primary endpoint was a composite of death, reinfarction, recurrent ischemia, new or worsening heart failure, or cardiogenic shock at 30 days. This occurred in 11.9% of the enoxaparin patients and in 11.6% of the UFH group – a non-significant difference (adjusted odds ratio 0.95; p=0.84), the authors report.
Crossover between heparin types occurred in 221 patients. In the subgroup of patients who received only one type, the primary endpoint rate was borderline lower in those given enoxaparin (7.1%) than in those treated with UFH (11.5%; p=0.07), according to the report.
Overall, rates of access site bleeding were 5.0% versus 2.9% (p=0.04) with enoxaparin compared with UFH, and rates of mild bleeding were 12.1% versus 7.8% (p=0.03), the investigators found. However, mild bleeding risks were similar among the single-heparin group at 9.4% with enoxaparin and 7.5% with UFH (p=0.37).
Summing up the clinical implications, Dr. Goodman and colleagues conclude: “In patients with STEMI who are treated by an invasive approach after initial treatment with fibrinolysis, enoxaparin administration as an adjunct to tenecteplase is associated with similar efficacy and safety compared with that of UFH.”
Furthermore, they add, “Crossover from enoxaparin to UFH in this setting should probably be avoided because it is associated with more mild bleeding and may impact upon the efficacy of anticoagulation in these patients.”
Am Heart J 2012;163:176-181.e2.