Coronary artery disease (CAD) is common in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI), but its clinical relevance is controversial. At present, the optimal means of defining CAD in patients undergoing TAVI with respect to its prognostic implications and the assessment of myocardial ischaemia is not known. For this reason, the best treatment options are a matter for debate, and current guidelines do not recommend revascularization. As the indications for TAVI expand, the lack of any rigorous means of guiding coronary revascularization might negatively affect the clinical outcomes of future patients. In this Review, we summarize the methods of assessing CAD in TAVI populations, and the data on the safety and efficacy of percutaneous coronary intervention in patients undergoing TAVI. We discuss the putative effects of aortic stenosis on the functional assessment of CAD using pressure or flow wires or by noninvasive stress testing. We propose that a new, well-validated method of assessing CAD as a cause of myocardial ischaemia-which distinguishes it from myocardial infarction, previous revascularization, or non-flow-limiting disease-in patients with severe aortic stenosis is needed to guide revascularization in the current era of TAVI.