Introduction

Heparin-induced thrombocytopenia (HIT) presents a unique situation: heparin causes the very complications its use was intended to prevent, e.g., pulmonary embolism, stroke, and limb gangrene. Furthermore, several treatment paradoxes pose serious management pitfalls (Table 1). This chapter summarizes our treatment approaches, with emphasis on practical management issues. We wish to highlight two important issues. First, HIT is a syndrome of increased thrombin generation ("hypercoagulability state"). Accordingly, we emphasize the use of rapidly acting anticoagulant drugs that control thrombin generation in HIT. Second, there is increasing evidence that in most patients in whom testing for HIT antibodies is requested, a non-HIT diagnosis ultimately is made (Juhl et al., 2006; Lo et al., 2006). Thus, the risk of failing to prevent a HIT-associated thrombosis (through timely use of a non-heparin anticoagulant) must be balanced against the risk of inducing adverse effects from using another anticoagulant, e.g., bleeding complications for which no antidote exists.

This chapter is not the outcome of a formal consensus conference, as defined elsewhere (Mclntyre, 2001). Nevertheless, we have used an evidence-based approach to frame our recommendations, modeled after the Seventh American College of Chest Physicians (ACCP) Consensus Conference on Antithrombotic Therapy (Warkentin and Greinacher, 2004). According to these guidelines, the recommendation to use (or not to use) a particular treatment is based on the tradeoff between the expected benefits on the one hand and the risks on the other. Thus, based upon the evidence, as well as our own experience, when we concluded that benefits of a particular treatment generally outweighed the risks, we recommended the treatment. If we were quite certain the evidence favored the recommendation, a level 1 recommendation was made. If we were less certain of the trade-off between benefits and risks, a weaker recommendation (level 2) was made.

We also assessed the methodological quality of the studies supporting the recommendations, also using the ACCP guidelines: grade A: randomized controlled trials (RCTs) without important limitations; grade B: RCTs with important limitations; and grade C: observational studies.

Regarding studies of HIT, there is only one small RCT (Chong et al., 2001), and this study had methodological flaws such as non-blinded assessment of

TABLE 1 Treatment Paradoxes of HIT Management

Treatment for HIT

Paradoxical effect of treatment

Comments

Discontinue heparin

Coumarin (e.g., warfarin, phenprocoumon)

0 0

Post a comment