Valve replacement is recommended when aortic stenosis is severe and there is any one of the following: Symptoms Exercise testing causing symptoms or showing reduced effort tolerance or a fall in blood pressure ≥ 10 mm Hg below baseline) LV EF < 50% If surgical risk is low, then surgery may be considered if there is any one of: Very severe AS (aortic velocity > 5 m / second) Brain (B-type) natriuretic peptide (BNP) is > 3 times normal Severe pulmonary hypertension without other explanation Decline in EF to < 60% Severe valve calcification with rapid progression of stenosis (reduction in aortic valve area ≥ 0.3 m / second / year) Studies are ongoing to determine whether earlier surgical intervention may be warranted as the risks of SAVR and TAVI decline.