We discuss the clinical assessment of heart valve substitutes, primari
ly with regard to pre-market evaluation. We concentrate on the current
FDA heart valve guidance document. This guidance is self-acknowledged
to be an evolving document, scheduled to be revised between three and
five years after its initial release on December 1993. We outline the
history and some of the strengths of the present system, and discuss
areas for possible improvement. We selected one important statistical
issue to address thoroughly how to compute the confidence limit of a l
inearized rate.