Use of activated partial thromboplastin time to monitor coumarin anticoagulation.

The activated partial thromboplastin time after heparin removal (aPTT/HR) is an anionexchange procedure that permits the unobstructed monitoring of the progress of coumarin anticoagulation by removing interfering heparin. An all-intrinsic-pathway anticoagulant surveillance scheme based upon the aPTT/HR has been proposed and provisionally tested. The adoption of the new scheme will depend upon the identification of partial thromboplastins that are as predictable and reliable as the tissue thromboplastins in modern one-stage prothrombin times. In this study, the commercial APTT Reagent and Simplastin performed with equal sensitivity and specificity when evaluated by means of prothrombin group factor assays on coumarintreated subject plasmas. It is concluded that this commercial partial thromboplastin (1) is capable of being used for the purpose of following heparin, heparin plus coumarin, and coumarin anticoagulation; (2) is potentially able to identify more of the inherited and acquired derangements that can lead to anticoagulation-associated hemorrhage; and (3) is a universally available alternative to the traditional anticoagulant monitoring approach.