The 1979 registry collected cases prospectively beginning in 1979 as well as retrospectively back to the introduction of the procedure in 1977. To participate in the registry, centers were required to submit data on all patients who had a guide catheter introduced as the first step in the angioplasty procedure. From 1979 to 1982 3,248 patients were entered from 105 clinical sites and in 1982, the registry stopped entering new cases and shifted its effort to follow-up. Sixteen of the largest centers participated in the five year follow-up. During the follow-up period, the range of patients expanded greatly with technologic advances and clinical experience. The registry was reopened in 1985 to confirm and document changes in angioplasty techniques and results. Methods of data collection in the new registry were the same as in the old. Within ten months, 2,094 new patients were enrolled.