COMMUNICATIONS Proc R Coll Physicians Edinb 2001; 31:208-215208 PREVALENCE OF AORTIC SCLEROSIS IN THE ELDERLY

Increasing use of echocardiography has demonstrated a higher prevalence of mild aortic valve disease than was previously recognised. In the population-based Cardiovascular Health Study, echocardiography documented mild irregular thickening of the aortic valve leaflets in 25% of adults over the age of 65 years.1 In this condition, termed ‘aortic sclerosis’, no obstruction occurs to left ventricular outflow. A similarly high prevalence of aortic sclerosis has been found in other studies; prevalence increases with ageing such that almost half of adults over the age of 84 have some degree of aortic valve sclerosis.2 Aortic sclerosis is one end of a disease spectrum; severe aortic stenosis with significant narrowing of valve opening resulting in clinical symptoms is the end-stage of this disease process (Table 1). present. Extracellular material is increased and it consists of protein, proteoglycans and lipids. Oil-Red-O staining of frozen specimens demonstrates large amounts of extracellular neutral lipid in this site which specific markers for apolipoproteins can identify as being consistent with low density lipoprotein (LDL) and lipoprotein(a) (Lp(a)).4, 5 Oxidation of LDL is also demonstrable in the lesions of aortic sclerosis and stenosis (Figure 1).6 Even in early lesions, microscopic mineralisation is present, as seen on von Kossa staining for calcium. As the disease progresses, the amounts of calcification increase, with the end-stage disease seen in patients undergoing valve replacement being characterised by large amounts of extracellular calcification, as well as lipid accumulation. The calcification process appears to be active, with a subset of the local macrophages producing osteopontin, a protein involved in calcification.7, 8 Most recently, our group has demonstrated the presence of angiotensin converting enzyme in the early lesions of aortic stenosis, again emphasising that this is an active disease process, not just an inevitable consequence of ageing.