A baseline TTE study is recommended after all valve inter- ventions, including replacement with a prosthetic valve (see Section 11.1). This baseline postproce- dural study ideally is performed 1 to 3 months after intervention to ensure loading conditions have returned to normal, but in some cases it may need to be done during the index hospital- ization for the patient s convenience. The tim- ing of subsequent periodic imaging after valve intervention is based on the type of valve pros- thesis or repair, length of time after valve inter- vention, residual valve dysfunction, ventricular size and systolic function, and any concurrent cardiac conditions (Table 12). TTE is the standard approach for periodic imaging, supplemented by TEE when prosthetic mitral valve dysfunction is a concern (see Section 11.1). Additional imaging with CT, fluoroscopy CMR, or PET is reserved for patients for whom there is concern about valve dysfunction (see Section 11.1) or endocarditis (see Section 12.1).1,2 3. AORTIC STENOSIS 3.1. Stages of Valvular AS Medical and interventional approaches to the manage- ment of patients with valvular AS depend on accurate diagnosis of the cause and stage of the disease process. Table 13 shows the stages of AS, ranging from patients at risk of AS (Stage A) or with progressive hemody- namic obstruction (Stage B) to severe asymptomatic (Stage C) and symptomatic AS (Stage D). Each stage is defined by patient symptoms, valve anatomy, valve hemodynamics, and changes in the LV and vascula- ture. Hemodynamic severity is best characterized by the transaortic maximum velocity (or mean pressure gradi- ent) when the transaortic volume flow rate is normal. 