Preprocedural CT evaluation of transcatheter aortic valve replacement: What the radiologist needs to know

Aortic valve stenosis is the most common valvular heart disease in the Western world. When symptomatic, aortic valve stenosis is a debilitating disease with a dismal short-term prognosis, invariably leading to heart failure and death. Elective surgical valve replacement has traditionally been considered the standard of care for symptomatic aortic valve stenosis. However, several studies have identified various subgroups of patients with a significantly elevated risk for surgery-related complications and death. Thus, not every patient is a suitable candidate for surgery. Recent developments in transcatheter-based therapies have provided an alternative therapeutic strategy for the nonsurgical patient population known as transcatheter aortic valve replacement (TAVR) (also called transcatheter aortic valve implantation or percutaneous aortic valve replacement). In TAVR, the native aortic valve is replaced with a bioprosthetic valve via a nonsurgical endovascular, transaortic, or transapical pathway. Nevertheless, several anatomic and technical criteria must be met to safeguard patient eligibility and procedural success. Therefore, noninvasive imaging plays a crucial role in both patient selection and subsequent matching to a specific transcatheter valve size in an effort to ensure accurate prosthesis deployment and minimize peri- and postprocedural complications. The authors review the relevant anatomy of the aortic root, emphasizing the implications of anatomic pitfalls for correct reporting of imaging-derived measurements and important differences between findings obtained with different imaging modalities. They also discuss the evolving role of computed tomography and the role of the radiologist in patient triage in light of current viewpoints regarding patient selection, device size selection, and the preprocedural evaluation of possible access routes.