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	Since this article does not have an abstract, we have provided the first 150 words of the full text and any section headings.

In their recent article, Hull et al¹ state that "inadequate initial heparin therapy predisposes patients to late recurrence of thromboembolism [TE]." They defined "inadequate heparin therapy" as the failure of the activated partial thromboplastin time (aPTT) to reach a preselected value within 24 hours of the initiation of heparin therapy, without providing any evidence that patients whose aPTT did not reach this level received inadequate treatment. In fact, several points argue against this assumption.

First, despite the widespread use of the aPTT in monitoring heparin therapy, the correlation between aPTT prolongation and plasma heparin levels in individual patients remains poor.² Increased levels of factor VIII, fibrinogen, and other plasma proteins may shorten the aPTT without reducing the anticoagulant effect of heparin.³ Thus, the fact that aPTTs of some subjects fell below the designated therapeutic range does not imply that these patients received inadequate heparin therapy.

Second, Hull et al¹ used . . . [Full Text of this Article]