Unfractionated heparin dosing; hard to get it right

This analysis is from a large prospective trial of over 20,000 patients with STEMI who were randomized to unfractionated (UFH) or low molecular weight heparin (LMWH). UFH was dosed bythe ACC/AHA weight based nomogram, with centrally monitored aPTTs (60 U/kg bolus and 12 U/kg/hour gtt). Despite 99% adherence to the nomogram, only 34% of initial aPTT’s were therapeutic. Markedly low aPTT’s (13%) were associated with increased risk reinfarction (OR 2.2), and markedly high aPTT’s (16%) were associated with minor or major bleeding (OR 2.1). Markedly high aPTT’s were more likely in patients that were older, female, lower weight, or with renal dysfunction. Unfortunately, even in the best of circumstances, we achieve therapeutic initial levels only 1/3 of the time, reminding us to remain vigilent despite protocols, especially in patients with the above risk factors (abstract).

Danielle Scheurer

Dr. Scheurer is a clinical hospitalist and the Medical Director of Quality and Safety at the Medical University of South Carolina in Charleston, South Carolina, and is Assistant Professor of Medicine. She is a graduate of the University of Tennessee College of Medicine, completed her residency at Duke University, and completed her Masters in Clinical Research at the Medical University of South Carolina. She also serves as the Web Editor and Physician Advisor for the Society of Hospital Medicine.

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