Diagnostic Testing: Initial Diagnosis Recommendations for Diagnostic Testing: Initial Diagnosis of AS Referenced studies that support the recommendations are summarized in Online Data Supplement 3. COR LOE Recommendations In patients with signs or symptoms of AS or a BAV, TTE is indicated for accurate diagnosis of the cause of AS, assessment of hemodynamic severity, measurement of LV size and systolic function, and determination of prognosis and timing of valve intervention.1,2 In patients with suspected low-flow, low- gradient severe AS with normal LVEF (Stage D3), optimization of blood pressure control is recommended before measurement of AS severity by TTE, TEE, cardiac catheterization, In patients with suspected low-flow, low- gradient severe AS with reduced LVEF (Stage D2), low-dose dobutamine stress testing with echocardiographic or invasive hemodynamic measurements is reasonable to further define severity and assess In patients with suspected low-flow, low- gradient severe AS with normal or reduced LVEF (Stages D2 and D3), calculation of the ratio of the outflow tract to aortic velocity is reasonable to further define severity.1,11 13 In patients with suspected low-flow, low- gradient severe AS with normal or reduced LVEF (Stages D2 and D3), measurement of aortic valve calcium score by CT imaging is reasonable to further define severity.14 18 Synopsis The overall approach to the initial diagnosis of VHD is discussed in Section 2.3, and additional consid- erations specific to patients with AS are addressed here. Recommendation-Specific Supportive Text 1. In adult patients, physical examination may not be accurate for diagnosis of and assessment of severity of AS. Echocardiographic imaging allows reliable evaluation of valve anatomy and motion and the degree of valve obstruction. In addition, TTE is useful for measuring LV size and systolic function, identifying concurrent AR or MR, and estimating pulmonary systolic 2. 