Does non-invasive carotid testing influence the selection of patients for carotid surgery?

To help define the role of non-invasive carotid testing, all patients undergoing carotid endarterectomy between January 1/1978 and December 31/1983 were reviewed. In late 1979, non-invasive carotid tests became available. No significant changes in the indications for carotid endarterectomy occurred in this interval, and all carotid patients were investigated with arteriography prior to operation. In this setting, we investigated the role, if any, of the carotid laboratory. Within two years of introduction, 1200 carotid tests were performed annually, a level which remained stable. It was found that the percentage of patients with significant lesions at arteriography increased, and the proportion of patients progressing to surgery after arteriography went up by 50%. Remarkably, the number of arteriograms did not increase in this interval. The present ratio of non-invasive studies to angiograms is 12:1, but when this ratio was only 4.6:1 in 1980, the increased yield of surgery following angiography was already noted. These results indicate that the non-invasive tests increase the accuracy of clinical diagnosis, place relatively fewer patients at risk from angiography, and are readily accepted and used by clinical staff even when angiography is used to evaluate all possible operative candidates. The results suggest that these benefits can be realized when non-invasive tests are ordered when necessary after careful clinical evaluation, and that their use as a screening measure in all patients with possible cerebrovascular disease may not be necessary.