The choice of surgical versus transcatheter AVR for patients with an indication for AVR is discussed in Section 3.2.4.1 3,5,6,12 16,35,42,47 55 2. In asymptomatic patients with severe AS and normal LV systolic function, the survival rate dur- ing the asymptomatic phase is similar to that of age-matched controls, with a low risk of sud- den death (<1% per year) when patients are fol- lowed prospectively and when patients promptly report symptom onset. However, in patients with a low LVEF and severe AS, survival is better in those who undergo AVR than in those treated medically. The depressed LVEF in many patients is caused by excessive afterload (afterload mis- match), and LV function improves after AVR in such patients. If LV dysfunction is not caused Figure 2. Timing of intervention for AS. Colors correspond to Table 2. Arrows show the decision pathways that result in a recommendation for AVR. Periodic monitoring is indicated for all patients in whom AVR is not yet indicated, including those with asymptomatic (Stage C) and symptomatic (Stage D) AS and those with low-gradient AS (Stage D2 or D3) who do not meet the criteria for intervention. See Section 3.2.4 for choice of valve type (mechanical versus bioprosthetic [TAVI or SAVR]) when AVR is indicated. 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. 