The activated clotting time can be used to monitor the low molecular weight heparin dalteparin after intravenous administration.
OBJECTIVE
This study was designed to compare the dose response of dalteparin versus unfractionated heparin (UFH) on the activated clotting time (ACT), and to determine whether the ACT can be used to monitor intravenous (IV) dalteparin during percutaneous coronary intervention (PCI).


BACKGROUND
The use of low molecular weight heparin (LMWH) during PCI has been limited by the presumed inability to monitor its anticoagulant effect using bedside assays.


METHODS
This study was performed in three phases. In vitro, ACTs were measured on volunteer (n = 10) blood samples spiked with increasing concentrations of dalteparin or UFH. To extend these observations in vivo, ACTs were then measured in patients (n = 15) who were sequentially treated with IV dalteparin and then UFH. Finally, a larger monitoring study was undertaken involving patients (n = 110) who received dalteparin 60 or 80 international U (IU)/kg alone or followed by abciximab. We measured ACT (Hemochron), activated partial thromboplastin time (aPTT), plasma anti-Xa and anti-IIa levels, tissue factor pathway inhibitor (TFPI) concentration, and plasma dalteparin concentration.


RESULTS
Dalteparin induced a significant rise in the ACT with a smaller degree of variance as compared to UFH. Five min after administration of IV dalteparin 80 IU/kg the ACT increased from 125 s (122 s, 129 s) to 184 s (176 s, 191 s) (p < 0.001). The aPTT, anti-Xa and anti-IIa activities, and TFPI concentration also demonstrated significant increases following IV dalteparin.


CONCLUSIONS
The ACT and aPTT are sensitive to IV dalteparin at clinically relevant doses. These data suggest that the ACT may be useful in monitoring the anticoagulant effect of intravenously administered dalteparin during PCI.
Marmur
Jonathan D
JD
Department of Medicine, Division of Cardiology, SUNY Health Science Center at Brooklyn, 450 Clarkson Avenue, Box 1257, Brooklyn, NY 11203, USA. jonathan@marmur.com
Anand
Sunil X
SX
Bagga
Ramanjit S
RS
Fareed
Jawed
J
Pan
Chi-Miau
CM
Sharma
Samin K
SK
Richard
Merwin F
MF
D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D000925:Anticoagulants / Q000008:administration & dosage* / Q000627:therapeutic use*; D003327:Coronary Disease / Q000628:therapy*; D017985:Dalteparin / Q000008:administration & dosage* / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006493:Heparin / Q000008:administration & dosage* / Q000627:therapeutic use*; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D010314:Partial Thromboplastin Time; D014914:Whole Blood Coagulation Time
D000925:Anticoagulants; D006493:Heparin; D017985:Dalteparin