MRI in Randomised Cohorts of Asymptomatic AS

Aortic stenosis is narrowing of the aortic valve, and is the commonest type of valve disease requiring surgery. Current guidelines recommend waiting till patients develop symptoms (chest pain, breathlessness and dizzy spells/fainting) before possible open heart surgery to replace the valve is offered. However, studies using detailed 'MRI' scanning of the heart have shown that up to half of the patients already have 'scarring' in the heart by the time symptoms develop. Furthermore, scarring is not fully reversed even after surgery and is associated with worse outcome. This suggests that some patients are being offered treatment too late. Two randomised trials in the UK (EASY AS and EVOLVED) are currently investigating if valve replacement before symptoms will result in better survival. The aim of this study is to compare the effect of early valve replacement versus waiting for symptoms, on the amount of scarring in the heart. The investigators want to know if early treatment leads to less overall scarring at the end, and leads to better quality of life and recovery after surgery. The investigators will invite participants of the EASY AS and EVOLVED trials to have 1-2 MRI heart scans: at recruitment and 3 years after being randomly allocated to early aortic valve replacement vs 'watchful waiting'. The investigators will also assess the impact of the two treatment approaches on quality of life, disability-free survival (using questionnaires) and recovery after surgery. The results from this project will increase understanding of the results of the main trials, and lead to improved selection of patients with aortic stenosis who are likely to benefit from early surgery.

Ongoing randomised control trials (RCT) are testing the strategy of early AVR in asymptomatic severe AS ('The Early surgery in severe ASYmptomatic Aortic Stenosis': EASY-AS and 'Early Valve Replacement guided by Biomarkers of Left Ventricular Decompensation in Asymptomatic Patients with Severe Aortic Stenosis': EVOLVED), and if positive, have the potential to shift the timing of intervention to earlier disease. With TAVR recently being shown to be non-inferior to SAVR in low risk, mostly symptomatic patients, this also has the potential to be extended to asymptomatic patients.

MRI studies have shown that up to 50% of those with asymptomatic AS already have scarring (LGE), which is only partially reversible even after AVE, and remains a marker of mortality. It is not known if earlier valve replacement will lead to less scar burden within the myocardium.

Patient reported outcome measures (PROM) are increasingly recognised as an important outcome measure of surgery, especially in an elderly population, for whom a significant increase in survival may be neither possible, nor sought by the patient. World Health Organisation Disability Assessment Schedule-2 (WHODAS-2) is a standardised cross-cultural measurement of health status assessing functioning and disability in major life domains, that has been shown to be a valid and reliable instrument for assessment of disability. A comprehensive formal review of PROMS instruments in patients receiving medical treatment for heart failure concluded that the Euroqol (EQ5D) and Minnesota Living with Heart Failure Questionnaire (MLHFQ) were the most appropriate to measure quality of life in this group. Euroqol is the most commonly used generic instrument in Europe, and showed improvement at 1 year post-AVR for severe AS. MLHFQ is a cardiovascular disease-specific tool that has been shown to be reliable, valid and responsive to therapeutic intervention in patients undergoing valve surgery. Understanding the effect of intervention on PROMs can aid shared decision-making and help shape future individualised recommendations.

This prospective, observational mechanistic study will maximise the opportunity offered by ongoing RCTs, to try and establish the effect of the two treatment strategies (early vs late AVR) on cardiac reverse remodelling (in particular fibrosis burden), PROMs and peri-operative recovery.

Eligibility Criteria:
Inclusion Criteria:

1. Willing to and able to consent
2. Participant in an RCT randomising patients with asymptomatic severe AS to early AVR vs standard care
3. Severe aortic stenosis, as defined by original trial's inclusion criteria
4. Asymptomatic at the time of randomisation in the RCT
5. Willingness to have 1-2 cardiac MRI scan(s)

Exclusion Criteria:

1. Contra-indication to MRI.
2. eGFR \<30.
3. Severe claustrophobia (precluding MRI).