Appropriate long-term oral anticoagulation prevents cardiogenic
thromboembolism to a large extent in patients with
artificial heart valves,
rheumatic heart disease,
myocardiopathy,
atrial fibrillation of non-rheumatic origin,
sick sinus syndrome,
cardiac aneurysm, and in the exceptional cases of
mitral valve prolapse with thromboembolic complications. In arterial
thrombosis, oral anticoagulation remains a controverted, probably because a much higher intensity would be needed to achieve the same degree of effectiveness. With target prothrombin times between 3.5 and 4 International Normalized Ratios (INRs) and a compliance of the INRs with the range of 2.5-5 INRs for greater than or equal to 80%, cardiogenic thromboemboli can be prevented in approximately 95% whereas only about two thirds of the cases of recurrent
coronary thrombosis can be avoided. The intensity and stability of treatment needed in cardiovascular
thrombosis involve a considerable risk of
bleeding, but--as shown by the results of the Dutch Sixty Plus Reinfarction Study--intracranial haemorrhages are more than compensated for by the prevention of cerebrovascular thromboembolic events. Appropriate administration of oral anticoagulation requires painstaking laboratory and therapeutic control, the former being based on continuous quality assessment and strict standardization of the prothrombin time. Therapeutic control consists of continuous patient education and adequate dosage regulation. Similar to the situation prevailing for
hemophilia patients, an organization must be available to which long-term anticoagulated patients can apply for expert advice. In The Netherlands, an organization has been built up on a voluntary basis, called Federation of
Thrombosis Centres, meeting this requirement and covering more than 90% of the country.