Medicare payment is often cited as a major driver of medical technology diffusion. Stakeholders claimed that beneficiaries would be denied access to stents because Medicare payment did not initially cover the cost of stents. Nevertheless, stents diffused rapidly, including to untested indications. Outcomes with stents improved over time, primarily because of a fundamental property of technology diffusion termed "reinvention," in which new technology is modified by users. The traditional system of regulatory approval and reimbursement does not account for this dynamic process. There has been no incentive for systematic collection of data to determine which modifications are most beneficial.