Introduction

Aortic stenosis (AS) is the most common valvular pathology in the elderly and prevalence is estimated at 4.6% in patients greater than 75 years of age.1 As the ageing population expands this is projected to increase rapidly in forthcoming decades.2 The majority of patients remain asymptomatic for many years and AS is associated with a low mortality risk in this setting.3 However, patients with severe AS who develop symptoms have very poor prognosis with significant reduction in survival and a 50% mortality within 2 years without treatment.4

Surgical aortic valve replacement (SAVR) has been the gold standard treatment for AS over the past 50 years. Careful patient selection, improved operative techniques and advances in valve design have resulted in excellent outcomes in contemporary series.5 ,6 However, in spite of these advances, SAVR is associated with a 5–10% risk of major adverse perioperative events and a mortality of up to 20% at 1 year7 ,8 in elderly patients. Consequently, a significant proportion of individuals are not offered or do not undergo SAVR and are managed conservatively with very poor outlook.

The emergence of transcatheter aortic valve implantation (TAVI) has revolutionised the treatment of symptomatic severe AS. Following ex vivo and in vivo testing,9 the first human procedure was undertaken by Cribier and colleagues in 200210 via an antegrade trans-septal approach. Subsequently, a number of registries,11 ,12 and randomised controlled trials,13–18 have demonstrated significant benefits of TAVI in inoperable and high-risk surgical candidates. To date, over 100 000 TAVI procedures have …