Exercise stress testing may be reasonable in the assessment of exercise capacity, stress-induced arrhythmias, and ischemia in patients with subAS and may be considered as an adjunct to echocar- diographic imaging. 2. Patients with symptomatic subAS should attain symptomatic improvement from surgical relief of the obstruction. In some cases, concomitant AVR may be needed, if indicated according to GDMT. 3. Patients with depressed LV systolic function and severe subAS may not manifest a resting gradient of 50 mm Hg. In this population, evaluation and decisions regarding surgical relief of LVOT obstruc- tion can be extrapolated from the existing aortic stenosis data and should be considered as per the Additionally, patients Table 17. Congenital Mitral 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. 6-minute walk test or CPET, depending on the clinical indication. ACHD indicates adult congenital heart disease; CPET, cardiopulmonary exercise test; ECG, electrocardiogram; and TTE, transthoracic echocardiogram. CLINICAL STATEMENTS AND GUIDELINES with preserved LV systolic function but poor LV compliance may present with signs or symptoms of HF and a resting maximum gradient <50 mm Hg. These patients may benefit from surgical re- lief of LVOT obstruction. Patients with evidence of resting or stress-induced ischemia in the absence of obstructive coronary artery disease and in the presence of moderate subAS (maximum gradient >30 mm Hg and <50 mm Hg) may benefit from surgical relief of subAS.S4.2.3-9 4. 