Comparison of Phenprocoumon and Acetylsalicylic Acid (ASA)

Patients will be allocated to two groups with either 1. anticoagulation with phenprocoumon (needed for at least 1 year) 2. therapy with ASA Both treatment groups should include to 50% patients with a glomerular filtration rate (GFR) \< 60 ml/min and \> 15 ml/min. All patients will undergo a screening procedure with evaluation of calcium regulating proteins, echocardiography and stratified computed tomography of the heart. Medical check up's are planned after 1,3,6, 12 and 18 months. Prior investigations concern diastolic ventricular function under long lasting therapy with phenprocoumon and the influence of long lasting therapy with phenprocoumon in patients suffering from aortic valve sclerosis.