Multiple interrelated factors (patient-, physician-, and prosthesis-related) affect patient survival after aortic valve replacement. Every aortic valve replacement is associated with a risk of death due to the surgical procedure. This risk may vary with the type of prosthesis that is implanted, and obviously increases with patient age and with each reoperation. In addition, the etiology of the valve lesion, concomitant procedures, and other wellknown risk factors may also affect operative mortality. Late survival of patients after aortic valve replacement differs considerably from survival of age-matched individuals in the general population. Fig. 1 shows that life expectancy of male patients after aortic valve replacement is significantly reduced compared to the age-matched population life expectancy. This difference in life expectancy is particularly evident in young adult patients. Operative mortality and the occurrence of valve-related events [1] (valverelated mortality) can only in part explain this difference, as is illustrated in Fig. 1 by the life expectancy of a patient who receives the - thus far hypothetical - perfect valve substitute, i.e., a valve substitute that has no associated valve-related complications. The remaining loss in life expectancy compared to the general population is depicted by the term excess mortality. Fig. 1. Absolute life expectancy (years) after aortic valve replacement with stented bioprostheses, mechanical prostheses and allografts compared to the age-matched Dutch population. Hypothetical immunity from valve-related events is depicted by the uninterrupted solid line just above the life expectancy estimates of the different prosthetic valve types