Functional assessment of coronary artery disease in patients with severe aortic stenosis: a review

A significant proportion of patients with severe aortic stenosis (AS) undergoing transcatheter aortic valve implantation (TAVI) have concomitant coronary artery disease (CAD). The best way to treat these patients is contentious. Conventional assessments of ischaemia such as fractional flow reserve (FFR) and instantaneous wave-free ratio are not validated in the context of severe AS despite having a Class I European Society of Cardiology indication in patients with isolated coronary disease. A better understanding of how we assess and interpret coronary physiology in these patients is required to optimise treatment pathways. Only one prospective, randomised trial has investigated the routine use of FFR to guide revascularisation in patients undergoing TAVI and several observational cohort studies have measured changes in hyperaemic and resting indices in patients with severe AS as well as before and after TAVI. The purpose of this review article is to provide a summary of the current data regarding the functional assessment of CAD in patients with severe AS and highlight the current best practice in this evolving area.