Effects of the early administration of heparin in patients with ST-elevation myocardial infarction treated by primary angioplasty

Background: The effect of adjunctive heparin for primary angioplasty in patients with ST-elevation myocardial infarction (STEMI) is not well established, so the authors investigated the effect of early heparin administration in the emergency room (ER) on initial patency of the infarct-related artery (IRA) and on the clinical outcome in STEMI patients. Methods and Results: One hundred and twenty consecutive patients who presented with STEMI less than 12 h from pain onset and who were eligible for primary percutaneous coronary intervention were allocated to an early heparin group (heparin administered in ER) or a late heparin group (heparin administered after angiography). In the early heparin group, unfractionated heparin (60 U/kg bolus IV, then 14U·kg^-1·h^-1 IV infusion) or enoxaparin (1 mg/kg bolus SC) were administered 144±95 min before angioplasty. No significant differences in baseline characteristics were observed between the early heparin group (n=56) and the late heparin group (n=64). However, initial Thrombolysis In Myocardial Infarction (TIMI) flow grade in the IRA was significantly different between the 2 groups (frequency of TIMI 0/1/2/3; 48/4/7/41% vs 70/8/11/11%, early vs late respectively, p=0.002). TIMI 2 or 3 flow was significantly more frequent in the early heparin group than in the late heparin group (48% vs 22%, p=0.002). However, no significant differences were noted between the 2 groups in terms of in-hospital major adverse cardiac events (7% vs 11%, p=0.472) and TIMI major bleeding (2% vs 3%, p=0.639). Conclusions: In STEMI patients, early heparin therapy administered in the ER improves coronary patency, despite not reaching clinical benefit.