AS indicates aortic stenosis; AVA, aortic valve area; AVAi, aortic valve area index; AVR, aortic valve replacement; BNP, B-type natriuretic peptide; BP, blood pressure; DSE, dobutamine stress echocardiography ETT, exercise treadmill test; LVEF, left ventricular ejection fraction; Pmean , mean systolic pressure gradient between LV and aorta; SAVR, surgical aortic valve replacement; SVI, stroke volume index; TAVI, transcatheter aortic valve implantation; TAVR, transcatheter aortic valve replace- ment; and Vmax , maximum velocity. CLINICAL STATEMENTS AND GUIDELINES by afterload mismatch, survival is still improved, likely because of the reduced afterload with AVR, but improvement in LV function and reso- lution of symptoms might not be complete after 3. Prospective clinical studies demonstrate that dis- ease progression occurs in nearly all patients with severe asymptomatic AS. Symptom onset within 2 to 5 years is likely when aortic velocity is 4.0 m/s or mean pressure gradient is 40 mmHg. The additive risk of AVR at the time of other cardiac surgery is less than the risk of reoperation within 4. Mean pressure gradient is a strong predic- tor of outcome after AVR, with better out- comes seen in patients with higher gradients. Outcomes are poor with severe low-gradient AS but are still better with AVR than with medi- cal therapy in those with a low LVEF, particu- larly when contractile reserve is present. The document Echocardiographic Assessment of Valve Stenosis: EAE/ASE Recommendations for Clinical Practice defines severe AS on dobuta- mine stress testing as a maximum velocity >4.0 m/s with a valve area 1.0 cm2 at any point dur- ing the test protocol, with a maximum dobu- tamine dose of 20 mcg/kg per minute.66 The recommendation for AVR in these patients is based on outcome data in several prospective nonrandomized studies. 