A novel enoxaparin regime for ST elevation myocardial infarction patients undergoing primary percutaneous coronary intervention: a WEST sub-study.
OBJECTIVE
To evaluate the anticoagulation effect of subcutaneous (SQ) and intravenous (IV) enoxaparin through systematic anti-Xa sampling during primary PCI for acute STEMI.


BACKGROUND
Although appropriate anticoagulation is essential to maximize the efficacy and safety of primary PCI, the optimal dosing of enoxaparin in this setting is unclear.


METHODS
STEMI patients randomized to primary PCI received ASA, clopidogrel 300 mg and enoxaparin 1 mg/kg SQ at earliest point of care, including prehospital. Plasma anti-Xa determination occurred just prior to and after primary PCI. Supplemental IV enoxaparin (0.3-0.5 mg/kg) and abciximab was encouraged prior to PCI.


RESULTS
The 1st anti-Xa level 56 min (median, IQR 47-77) post SQ enoxaparin was 0.28 U/ml (0.23-0.41); 85% of patients (28/33) were <0.5 U/ml (the recommended therapeutic level). Following PCI, 126 min (118-185) after SQ enoxaparin in those without IV dosing (8/33) the 2nd anti-Xa level was 0.44 U/ml (0.29-0.53); 6 of 8 patients remained <0.5 U/ml. With IV enoxaparin (25/33) the 2nd anti-Xa was 0.96 U/ml (0.82-1.16) 97 min (82-109) after SQ enoxaparin: all were >or=0.5 U/ml and 2 had levels 1.5 U/ml.


CONCLUSIONS
A single SQ enoxaparin dose fails to achieve anti-Xa levels >or=0.5 U/ml in the majority of STEMI patients. When combined with a strategy of supplemental IV enoxaparin, adequate anti-Xa levels were achieved in all patients with few having levels >1.5 U/ml. This regime of SQ injection with additional IV enoxaparin provides an attractive strategy enhancing effective early anti-thrombotic therapy at first medical contact prior to primary PCI.
Welsh
Robert C
RC
Division of Cardiology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada. rwelsh@cha.ab.ca
Gordon
Phillip
P
Westerhout
Cynthia M
CM
Buller
Christopher E
CE
O'Neill
Blair
B
Armstrong
Paul W
PW
D000077284:Abciximab; D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000379:methods*; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D002170:Canada; D000077144:Clopidogrel; D017023:Coronary Angiography; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D004562:Electrocardiography; D017984:Enoxaparin / Q000008:administration & dosage*; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage*; D005500:Follow-Up Studies; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000008:administration & dosage; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D016896:Treatment Outcome; D014505:Urban Population
D000911:Antibodies, Monoclonal; D017984:Enoxaparin; D005343:Fibrinolytic Agents; D007140:Immunoglobulin Fab Fragments; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D000077144:Clopidogrel; D013988:Ticlopidine; D000077284:Abciximab