Six almost unknown reasons why LMWH is better than unfractionated heparin in therapy of patients with present or threatening heart failure

摘要

The general advantages of low molecular weight heparin (LMWH) over unfractionated heparin (UFH) -and vice versa- are well-known. However, in patients with present or threatening heart failure (HF), other characteristics of LMWH become additionally advantageous. These characteristics are almost unknown and it can be useful to recognize them, because heparins are extraordinarily potent drugs (they might cause even fatal bleeding) and such patients are very prevalent. The first of the advantages of LMWH, especially important in HF patients, is subcutaneous (s.c.) administration - without infusion. On the contrary, UFH is given in therapeutic doses by means of infusion, so-called "heparin pump". It produces volume load, which can be very bad for patients with present or threatening HF, who are (or will become soon) overloaded. Furthermore, "heparin pump" requires immobilization, which is a thrombogenic situation per se. Besides, prolonged immobilization required for "heparin pump" undoubtedly produces stress, which is arrhythmogenic, enhances platelet aggregation, rises blood pressure (and thus afterload), may lead to vasospasm, etc. UFH damages veins, especially if "heparin pump" is administered more than 24 hours. In addition, UFH causes local bleeding at the infusion site. The damage of veins and local bleedings are more common in older patients with many comorbidities and HF patients are prototype for this. Moreover, the concentrations of the acute phase reactants are increased in HF, possibly leading to the UFH resistance. Furthermore, UFH can cause hyperkalemia, which complicates already delicate potassium regulation in HF.