Aortic stenosis - pathogenesis, prediction of progression, and percutaneous intervention.

Aortic stenosis is common and an important cause of morbidity and mortality. Prevalence will increase significantly in forthcoming decades as a function of the ageing population; treatment by means of surgery or percutaneous intervention is expensive. Epidemiological, mechanistic and interventional studies are therefore vital to determine optimal and innovative treatments and their funding. Recent studies suggest that aortic stenosis is not a passive degenerative disease, but an active process involving several pathways, including lipid infiltration, chronic inflammation, fibrosis formation, osteoblast activation, and active valve mineralisation. Despite similarities with atherosclerosis, randomised statin trials proved negative in aortic stenosis, underlining the need to explore alternative pathophysiological pathways. Left ventricular hypertrophy in response to pressure overload in aortic stenosis is initially adaptive but ultimately decompensates, leading to progressive left ventricular impairment, symptoms and adverse cardiovascular events. This transition is driven primarily by myocyte death and myocardial fibrosis. Cardiac magnetic resonance imaging can visualise and quantify myocardial fibrosis and may provide additional and independent prognostic information in aortic stenosis. Moreover, new markers of fibrosis utilising novel imaging techniques are rapidly emerging. Transcatheter aortic valve implantation is a disruptive technology that has transformed the management of aortic stenosis, and encouraged a wider multidisciplinary approach to the management of valvular heart disease. While originally applied in older, high-risk patients, recent trends for its use in intermediate risk patients have been supported by the findings of key clinical trials in 2016.