Of the 1,254 patients undergoing CABG operations during the study period, 1,079 patients (86%) had at least one postoperative cardiac catheterization. This included 1,074 patients with one or more SVG and 457 patients with an IMA graft. Two hundred twenty-five patients had a single postoperative catheterization (18%), 328 patients had two catheterizations (26%), 384 had three catheterizations (31%), 119 had four catheterizations (9%), and 23 had five catheterizations (2%). Patient status during each of the five angiographic periods is given in (Table 1). A total of 919, 799, 367, 170, and 369 patients had cardiac catheterizations nominally at the 1-week, 1-year, 3-year, 6-year, and 10-year periods, respectively. The median times to the catheterizations were 8 days and 1.0, 3.0, 6.2, and 9.7 years, respectively. Ninety-six and sixty-seven percent of the 6- and 10-year catheterizations, respectively, were performed for clinical, not study-related, reasons. The 10-year catheterizations occurred between May 1991 and January 1999. There were 523 deaths before the 10-year catheterization. Of these 523 patients, serial catheterizations or autopsy data were obtained on 396 patients (76%). One hundred thirty patients had a single catheterization before death (25%), 168 had two catheterizations (32%), 87 had three catheterizations (17%), and 11 had four catheterizations (2%). There were autopsy data with graft patency defined on 71 patients. The details of the patient data, including clinical outcomes and complications of the previous catheterizations, have been reported (8- 12). The clinical characteristics of patients with SVGs and IMA grafts (Table 2) are presented. The patients who did not undergo the 10-year catheterization had a higher incidence of diabetes (p = 0.022) and a trend toward more hypertension (p = 0.057) and a higher incidence of left main disease (p = 0.084) (Table 3).