4. Incidence of AS. Degenerative aortic valve disease evolves slowly from aortic sclerosis to aortic stenosis. Aortic sclerosis and stenosis are found in about 29% and 2-9% respectively in adults older than 65 years (4). In 5,201 subjects > 65 years, aortic valve sclerosis was present in 26% and AS in 2% of the entire study cohort; in subjects >75 years of age, sclerosis was present in 37% and stenosis in 2.6% (30). The prevalence of critical AS was 2.9% in the group 75 to 86 years of age in another study (42). In an observational study (43) which enrolled 953 subjects (aged 25-74 years), the overall prevalence of degenerative aortic valve disease (defined as the presence of valvular sclerosis, calcification, or thickening on echocardiographical examination) was 28%. The prevalence of degenerative aortic valve disease by age groups was the following: 7% (35-44 years), 19% (45-54), 30% (55-64), 38% (65-74) and 64% (75-84). There were no significant differences between men and women.