Widespread application of surgical treatment for valvular heart disease has made the diagnosis of prosthetic valve dysfunction of great clinical importance. Recent advances in cardiac imaging techniques, including color Doppler and transesophageal echocafdiography, provide such a detailed picture of valve anatomy and function that often cardiac catheterization adds little to the assessment. 1,2 Despite adequate noninvasive assessment of prosthetic valve function, adult patients continue to undergo cardiac catheterization before reoperation to rule out the development of new significant coronary artery disease. This is usually performed even if the patient has been shown to be free of coronary artery disease at the time of initial valve surgery. The frequency with which significant coronary artery disease develops or progresses in patients with valvular heart disease and the diagnostic yield of repeat coronary arteriography have not been adequately defined. This study examines a consecutive series of patients with prosthetic heart valves who underwent cardiac catheterization for recurrent symptoms to determine (1) the frequency with which new significant coronary disease develops in patients without previous disease, (2) the frequency with which new significant lesions appear in patients with known disease, and (3) clinical parameters that may identify patients with new significant coronary artery disease.