<qa>  What is the plasma-renin activity assessed prior to surgery?Prior to surgery and at each follow-up visit venous blood samples will be drawn for analysis of plasma N-terminal proBNP, and of plasma N-terminal ANP concentrations. In addition prior to surgery and after 6 and 12 months treatment with candesartan RAAS activity will be assessed using plasma-renin activity, plasma-aldosterone, and plasma-noradrenalin. In addition plasma will be frozen at each visit for possible later analysis. 