[The prophylaxis against venous thromboembolic complications in internal medicine--the gap between theory and practice].

Venous thromboembolism is an important cause of morbidity and mortality in internal medicine but antithrombotic prophylaxis is not being sufficiently used in comparison with surgical settings. In medical patients there are usually multiple risk factors, often with cumulative effect and the comprehensive risk assessment is complicated. The most important agents for pharmacological thromboprophylaxis are heparins - unfractionated and low-molecular-weight. The metaanalysis of randomised trials comparing unfractionated or low-molecular-weight heparin against control (placebo or aspirin) in medical patients has confirmed a significant risk reduction for deep vein thrombosis (56 %) as well as pulmonary embolism (58 %). Low-molecular-weight heparin is as effective as unfractionated heparin in reducing mortality as well as venous thromboembolism but has the advantage of significantly fewer bleeding complications. A novel synthetic pentasaccharide antithrombotic agent fondaparinux has been successfully proved in thromboprophylaxis in medical patients too. In most trials the duration of pharmacological prophylaxis was up to 2 weeks, the possible benefit of extended prophylaxis has not been clarified yet. Specific groups are intensive care patients; the elderly for their high thromboembolic as well as bleeding risk and significant comorbidity; the patients with acute ischaemic stroke who have very high thromboembolic risk but there are concerns about the risk of haemorrhagic transformation of stroke. The economic studies have shown that low-molecular-weight heparin in prophylactic doses in acutely ill medical patients is cost-effective strategy.