Effect of Aortic Valve Replacement on Myocardial Perfusion and Exercise Capacity in Patients with Severe Aortic Stenosis od Saadia Aslam, Abhishek Dattani, Aseel Alfuhied, Gaurav Gulsin, Jayanath Arnold, Christopher Steadman, PhD, Michael Jerosch-Herold, PhD, Hui Xue, PhD, Peter Kellman, PhD, Gerry McCann, Anvesha Singh