Stress Aortic Valve Index for Assessing Risk in Aortic Valve Stenosis Patients

Discrepancies exist among aortic stenosis severity classification, patient symptom burden, and - in some cases - even survival. The new Stress Aortic Valve Index (SAVI) metric correlates better with transvalvular flow and might be a better predictor of symptoms and prognosis. The current study will demonstrate the value of SAVI (both non-invasive and invasive) in patients with moderate aortic stenosis. The population will consist of subjects at least 50 years old with moderate aortic stenosis (defined as aortic valve area \>1.0 cm2 plus either maximal velocity 2.5-3.9 m/s or mean gradient 15-39 mmHg). Subjects with severe concomitant valve disease or severe unrevascularized coronary artery disease will be excluded, so that the isolated prognosis of aortic stenosis can be investigated. All subjects will undergo invasive SAVI measurements during catheterization. Furthermore patients will receive non-invasive testing with an exercise echocardiogram and computed tomography (CT) scan for non-invasive SAVI measurements. The short-term objective will compare SAVI with standard resting indexes for symptom burden, functional capacity, and biomarkers. The long-term objective will associate SAVI and standard resting indexes with clinical outcomes related to valvular disease. The investigators hypothesize that low SAVI (more marked AS during stress) will track with more symptoms and a worse prognosis. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The patients will have several study visits. The index visit will be planned to obtain informed consent and baseline parameters. The measurement visit(s) will consist of the invasive SAVI measurement, echocardiogram, stress echo imaging, 6-minute walk test, quality of life questionnaire, and the cardiac CT. During the final visit after 12 months, subjects will undergo a CT valvular calcium scan, quality of life questionnaire, and 6-minute walk test. Every subject will have an echocardiogram yearly as suggested by guideline criteria and could possibly be contacted until five years after enrollment. Blood samples will be drawn at baseline and the 1-year follow-up. Potentially the new SAVI metric could identify patients at higher risk among those with moderate gradient AS. However, since no outcome data currently exists regarding SAVI and prognosis, no conclusions could be derived from these measurements until study completion.