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. LVEF typically increases by 10 LVEF units and may return to normal if afterload mismatch was the cause of LV systolic dysfunction. If dobutamine stress testing indi- cates moderate, not severe AS, GDMT for HF can be continued without AVR. Patients without contractile reserve may also benefit from AVR, but decisions in these high-risk patients must be individualized because outcomes are poor with either surgical or medical therapy. The role of TAVI in these patients is currently under 5. A subset of patients with severe AS presents with symptoms and with a low velocity, low gradient, and low stroke volume index, despite a normal LVEF. Low-flow, low-gradient severe AS with preserved LVEF should be considered in patients with a severely calcified aortic valve, an aortic velocity <4.0 m/s (mean pressure gradient <40 mmHg), and a valve area 1.0 cm2 when stroke volume index is <35 mL/m2 . Typically, the LV is small, with thick walls, diastolic dysfunction, and a normal LVEF ( 50%). The first diagnostic step is to ensure that data were recorded and mea- sured correctly. If hypertension is present, blood pressure is controlled before reevaluation of AS severity. Next, valve area is indexed to body size because an apparent small valve area may be only moderate AS in a small patient; an aortic valve area index 0.6 cm2 suggests severe AS. 