Supravalvular Aortic Stenosis: Routine Follow-Up and Testing Intervals Frequency of Routine Follow-Up and Testing Physiological Stage A* (mo) Physiological Stage B* (mo) Physiological Stage C* (mo) Physiological Stage D* (mo) *See Tables 3 and 4 for details on the ACHD AP classification system. Routine TTE may be unnecessary in a year when CMR imaging is performed unless clinical indications warrant otherwise. CMR may be indicated for assessment of aortic anatomy. Baseline study is recommended with periodic follow-up CMR, with frequency of repeat imaging determined by anatomic and physiological findings. If CCT is used instead of CMR imaging, the frequency should be weighed against radiation exposure. 6-minute walk test or CPET, depending on the clinical indication. ACHD indicates adult congenital heart disease; CCT, cardiac computed tomography; CMR, cardiovascular magnetic resonance; CPET, cardiopulmonary exercise test; ECG, electrocardiogram; and TTE, transthoracic echocardiogram. CLINICAL STATEMENTS AND GUIDELINES Recommendation-Specific Supportive Text 1. TTE with Doppler imaging is useful in deriving peak and mean pressure gradients across the area of supravalvular aortic stenosis from apical, supra- sternal, and right parasternal views; however, vis- ualization of the full extent of supravalvular aortic stenosis with TTE is limited. TEE is superior in this regard, and 3D TEE allows excellent visualization of the narrowed ascending aorta. CMR and CTA provide comprehensive and detailed images of supravalvular aortic stenosis and are used with echocardiography in the assessment of patients before and after repair.S4.2.5-15 2. Impaired coronary perfusion may occur because of varying degrees of aortic valve leaflet adhe- sion to the narrowed sinotubular junction or because of fibrotic thickening in the area im- mediately surrounding the coronary ostia. This causes ostial stenosis with restriction in diastolic filling of the coronary arteries; the left coronary is most frequently involved. 