Inclusion Criteria:  Willing to and able to consent Participant in an RCT randomising patients with asymptomatic severe AS to early AVR vs standard care Severe aortic stenosis, as defined by original trial's inclusion criteria Asymptomatic at the time of randomisation in the RCT Willingness to have 1-2 cardiac MRI scan(s)  Exclusion Criteria:  Contra-indication to MRI. eGFR <30. Severe claustrophobia (precluding MRI).