Discordant Echocardiographic Grading in Low Gradient Aortic Stenosis (DEGAS Study) From the Italian Society of Echocardiography and Cardiovascular Imaging Research Network: Rationale and Study Design.

Background: Low-gradient aortic stenosis (LG-AS) is characterized by the combination of an aortic valve area compatible with severe stenosis and a low transvalvular mean gradient with low-flow state (i.e., indexed stroke volume <35 mL/m2) in the presence of reduced (classical low-flow AS) or preserved (paradoxical low-flow AS) ejection fraction. Furthermore, the occurrence of a normal-flow LG-AS is still advocated by many authors. Within this diagnostic complexity, the diagnosis of severe AS remains challenging. Objective: The general objective of the Discordant Echocardiographic Grading in Low-gradient AS (DEGAS Study) study will be to assess the prevalence of true severe AS in this population and validate new parameters to improve the assessment and the clinical decision-making in patients with LG-AS. Methods and Analyses: The DEGAS Study of the Italian Society of Echocardiography and Cardiovascular Imaging is a prospective, multicenter, observational diagnostic study that will enroll consecutively adult patients with LG-AS over 2 years. AS severity will be ideally confirmed by a multimodality approach, but only the quantification of calcium score by multidetector computed tomography will be mandatory. The primary clinical outcome variable will be 12-month all-cause mortality. The secondary outcome variables will be (i) 30-day mortality (for patients treated by Surgical aortic valve replacement or TAVR); (ii) 12-month cardiovascular mortality; (iii) 12-month new major cardiovascular events such as myocardial infarction, stroke, vascular complications, and rehospitalization for heart failure; and (iv) composite endpoint of cardiovascular mortality and hospitalization for heart failure. Data collection will take place through a web platform (REDCap), absolutely secure based on current standards concerning the ethical requirements and data integrity.