The influence of noninvasive tests on the selection of patients for carotid angiography.

Abstract

To assess the impact of noninvasive testing of the carotid vessels upon patient management, we analyzed the angiographic findings in 494 patients studied between 1978 and 1983 for suspected extracranial cerebrovascular disease. This longitudinal study revealed two changes in the pattern of angiographic results after introduction of noninvasive testing in the final months of 1979. The proportion of examinations that revealed less than 49% stenosis decreased significantly from 49% in 1978 to 19% in 1983 (p less than 0.001). During the same time, the proportion of examinations identifying 75-99% stenosis increased from 20% to 62% (p less than 0.001). The referring physicians and their patient population appeared to remain unchanged over these years. We believe the decline in patients with little or no disease is a consequence of better patient selection due to screening with noninvasive tests. We credit the increase in patients with 75-99% disease to additional patients identified by noninvasive tests. This study also points out that the role of noninvasive studies will necessarily be restricted because of inherent limitations in the techniques and that clinical judgment will remain the final arbiter with regard to the management of patients at risk for stroke.