OBJECTIVES: Aortic Stenosis (AS) is a severe cardiovascular condition the treatment of which often involves a major operation.  For a subgroup of patients medical management (MM) is the only treatment option due to procedural risk. A transcatheter aortic valve implantation device ‘CoreValve’, is a novel procedure, is less invasive and allows for the implantation of a replacement valve in this patient group. Since information is not yet available on key clinical parameters, we modified an existing early stage economic model to perform a value of information (VoI) analysis to informing the prioritisation of future research. METHODS: The underlying model used in the analysis is a 10-year Markov model was developed in Microsoft Excel. Treatment options were CoreValve and MM with parameters derived from published literature. All costs were taken from the most recent published sources. Decrements were applied to age-specific EQ-5D population norms to generate QALYs.  A probabilistic sensitivity was used to inform the global Expected Value of Perfect Information (EVPI) calculation. Deterministic one way analyses were used to select the variable groups and individual parameters on which partial EVPI (EVPPI) calculations were performed. Annual incident population estimates were derived from information in a large national database. RESULTS: Assuming a decision horizon of 10 years, an annual incident population of 4052 and a willingness to pay threshold of £30,000 per QALY gained the EVPI is £11.3 million. EVPPI estimates were generated for costs, utilities, overall survival (MM patients) and treatment effects. Of these, the VoI for baseline mortality and long term mortality reduction were greatest (£21,364,000 and £8,151,000 respectively). The VoI for all others was negligible CONCLUSIONS: Further information on long term survival would have the greatest impact on decision uncertainty. Thus, a new clinical trial may not be required and a registry may be more appropriate.