Thus, the criteria for severe VHD are based on predictors of clinical outcome from observational studies, registry data, and randomized clinical trials (RCTs) of pa- tients with VHD. Of course, severity is a continuous vari- able; categorizing disease into stages, from A to D, simply provides a framework, or starting point, for diagnosis and management, and it is recognized that not all patients will fit perfectly into a specific stage. Some patients will have symptoms or end-organ damage with valve hemo- dynamics that do not quite meet specific disease severity criteria, and numerical measures may not match exactly across all categories. Conversely, other patients may re- main asymptomatic without obvious evidence of end- organ damage despite apparently severe VHD. Criteria for the stages of each individual valve lesion are listed in and Section 8.1 (Table 20). 2.3. Diagnosis and Follow-Up 2.3.1. Diagnostic Testing: Initial Diagnosis TTE is the standard diagnostic test in the initial evalu- ation of patients with known or suspected VHD.1 4 LOE Level of Evidence LV left ventricle (left ventricular) LVEDD left ventricular end-diastolic dimension LVEF left ventricular ejection fraction LVESD left ventricular end-systolic dimension MDT multidisciplinary team MR mitral regurgitation MS mitral stenosis NOAC non vitamin K oral anticoagulant NYHA New York Heart Association PCI percutaneous coronary intervention PET positron emission tomography PMBC percutaneous mitral balloon commissurotomy RCT randomized controlled trial RV right ventricle (right ventricular) SAVR surgical aortic valve replacement TAVI transcatheter aortic valve implantation TEE transesophageal echocardiography (echocardiogram) TEER transcatheter edge-to-edge repair TR tricuspid regurgitation TTE transthoracic echocardiography (echocardiogram) UFH unfractionated heparin VHD valvular heart disease ViV valve-in-valve VKA vitamin K antagonist CLINICAL STATEMENTS AND GUIDELINES TTE allows accurate assessment of valve anatomy and etiology, concurrent valve disease, and associated ab- normalities, such as aortic dilation. 