Major advantages and critical challenge for the proposed United States heart allocation system.

The proposed new United States allocation system incorporates extensive research into an elegant plan designed to reduce wait list mortality while preserving post-transplant outcomes. All architects are to be congratulated. However, the future cannot be reliably modeled from the past as listing practices will evolve in response to new criteria. The new system should provide a major advance if and only if it is combined with a commitment to limit the number of listed patients overall and within each high priority status to the number that could reasonably undergo timely transplantation.