Anticoagulation after subcutaneous enoxaparin is time sensitive in STEMI patients treated with tenecteplase.
(Journal Article;Multicenter Study)
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.
Welsh, RC; Westerhout, CM; Buller, CE; O'Neill, B; Gordon, P; Armstrong, PW
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