title: Anticoagulation after subcutaneous enoxaparin is time sensitive in STEMI patients treated with tenecteplase.
abstract: The adequacy of anticoagulation with enoxaparin as an adjuvant to fibrinolytic therapy for STEMI is unclear and has implications for both efficacy and safety; especially in patients undergoing a pharmacoinvasive reperfusion strategy. A subset of fibrinolytic-treated patients in the WEST study was enrolled in a systematic anti-Xa substudy. All received ASA and subcutaneous (SQ) enoxaparin 1 mg/kg followed by TNK-tPA. Incremental IV dosing of enoxaparin (0.3-0.5 mg/kg) was allowed prior to percutaneous coronary intervention (PCI). Anti-Xa blood samples were drawn prior and after angiography. Data are presented as percentages, medians and IQRs. Forty-five patients underwent angiography 2.8 h (2.5-14.6) after fibrinolytic. The pre-angiography median anti-Xa acquired 179 min (153-875) after SQ enoxaparin was 0.48 U/ml (0.42-0.65); a relationship between anti-Xa activity and time from administration was evident (r = 0.418, p < 0.007). Without supplemental IV enoxaparin the 2nd anti-Xa acquired 218 min (195-930) after SQ enoxaparin was 0.48 U/ml (0.41-0.80, n = 29). After supplemental IV enoxaparin, the 2nd anti-Xa was 0.92 U/ml (0.72-1.10, n = 16). An incremental IV enoxaparin dose and anti-Xa relationship was demonstrated (r = 0.59, p = 0.001) i.e. no IV 0.48 U/ml (0.41-0.80, n = 29), 0.3 mg/kg IV 0.81 U/ml (0.63-1.00, n = 12), and 0.5 mg/kg IV 1.34 U/ml (1.16-1.54, n = 4). Most fibrinolytic treated STEMI patients receiving weight-adjusted SQ enoxaparin (1 mg/kg) had subtherapeutic anti-Xa levels (<0.5 U/ml) after ~3 h. A strategy of supplemental 0.3 mg/kg IV enoxaparin at time of PCI reliably achieved anti-Xa ≥ 0.5 U/ml. Our findings provide a rational novel strategy for anti-thrombotic management in STEMI patients undergoing a pharmacoinvasive reperfusion strategy.
authors.affiliation: 2C2 Cardiology, WMC, University of Alberta, 8440 112 St NW, Edmonton, AB T6G 2B7, Canada. Robert.Welsh@albertahealthservices.ca
authors.forename: Robert C
authors.initials: RC
authors.lastname: Welsh
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Westerhout
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Buller
authors.forename: Blair
authors.initials: B
authors.lastname: O'Neill
authors.forename: Phillip
authors.initials: P
authors.lastname: Gordon
authors.forename: Paul W
authors.initials: PW
authors.lastname: Armstrong
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000379:methods; D004305:Dose-Response Relationship, Drug; D017984:Enoxaparin / Q000008:administration & dosage*; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage*; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000628:therapy*; D011300:Preoperative Care / Q000379:methods; D000077785:Tenecteplase; D013997:Time Factors; D010959:Tissue Plasminogen Activator / Q000008:administration & dosage*
chemical_list: D017984:Enoxaparin; D005343:Fibrinolytic Agents; D010959:Tissue Plasminogen Activator; D000077785:Tenecteplase