One of the memorable publications of the last century was the 1968 Ross and Braunwald opinion paper on natural evolution of patients with aortic stenosis (AS) [1]. The graphic suggesting a long latent period followed by very rapid decline after symptom onset is one of the most presented at cardiology meetings, and has driven clinical guidelines over the last 50 years (Fig. 7.1). While this idealized evolution is appealing in its logic, there is an abundance of data suggesting the connection between AS and heart failure (HF) is far more complex. Not only are we dealing with a different disease (AS in 2024 is dominated by calcific valvular degeneration in the elderly rather than due to rheumatic or bicuspid aortic valvulopathies of 1968), but there is enormous overlap of other conditions associated with the classic symptoms of angina, syncope and dyspnea. As such it is time to reevaluate the impact of AS and redefine therapeutic strategies and thresholds for intervention. In this chapter we will review recent progress in our understanding of AS.