So, does low-molecular-weight heparin cause less heparin-induced thrombocytopenia than unfractionated heparin or not?

摘要

Heparin-induced thrombocytopenia (HIT) is a protlirombotic adverse effect of heparin caused by platelet-activating antibodies that recognize mul-timolecular complexes of the chemokine platelet factor 4 (PF4) when it is bound to heparin. The reduced risk of HIT and HIT-associated thrombosis (HITT) with low-molecular-weight heparin (LMWH) compared with unfractionated heparin (UFH) seems well established. It was demonstrated in a large randomized controlled trial (RCT),2 in several prospective nonrandomized comparisons, in metaanalyses of these (and other) studies, and also in several retrospective, but large-scale, population-based studies. Furthermore, in-study serologic investigations indicate much lower frequencies of anti-PF4/heparin antibody formation with LMWH compared with UFH. Finally, there is an underlying biological rationale, as larger, and presumably more immunogenic, PF4-polysacchari.de complexes are formed with UFH than with LMWH. The case in favor of LMWH vis-a-vis avoiding HIT would seemclosed. And yet, in this issue of CHEST (see page 1131),