Cardiac magnetic resonance imaging for the assessment of aortic stenosis

### Learning objectives Aortic stenosis (AS) is the most common valve lesion requiring surgery in the developed world1 and is common in the elderly, with up to 3% of those over the age of 75 thought to have severe disease.2 With an ageing population, the prevalence of AS is expected to double in the next 20 years.3 AS progresses slowly over many years and is associated with compensatory left ventricular (LV) remodelling (hypertrophy and fibrosis) that is important in the development of symptoms and risk of heart failure.4 Thus, the response of the myocardium to pressure overload may be as important as the severity of the AS. Despite many medical advances, either surgical aortic valve replacement (SAVR) or transcutaneous aortic valve replacement (TAVR) remains the only available effective treatment for this common condition. Currently, intervention is recommended once symptoms or systolic dysfunction develop, but there remains a small risk of sudden cardiac death in the patient with asymptomatic severe AS. Research has therefore been focused on identifying risk-stratification tools for earlier intervention in a select high-risk population, with the ultimate aim of improving outcome. Cardiac magnetic resonance (CMR) imaging is one such tool that offers accurate and non-invasive assessment of the valve and the myocardium, allowing comprehensive assessment of the effects of AS. The latest European Society of Cardiology (ESC) guidelines identify four categories of AS based on mean gradient, flow and ejection fraction (table 1), and multimodality imaging plays a key role in …