Role of conventional angiography in evaluation of patients with carotid artery stenosis demonstrated by Doppler ultrasound in general practice

Background and Purpose-Previous studies have suggested that patients with c arotid stenosis who are candidates for endarterectomy can be effectively id entified on the basis of carotid Doppler ultrasound alone. Before widesprea d acceptance of this policy, the accuracy of carotid Doppler ultrasound out side selected centers and clinical trials needs to be evaluated. We perform ed a 12-month prospective study to evaluate the accuracy of Doppler ultraso und in identifying patients for carotid intervention in general practice se ttings. Methods-Each patient referred to our endovascular service for diagnostic an giography to evaluate for carotid stenosis was interviewed and examined by a neurologist. Subjects consisted of symptomatic patients with greater than or equal to 50% stenosis and asymptomatic patients with greater than or eq ual to 60% stenosis by Doppler ultrasound. Information pertaining to demogr aphic and cerebrovascular risk factors and the results of the carotid Doppl er ultrasound were recorded. The severity of stenosis on angiograms was mea sured with North American Symptomatic Carotid Endarterectomy Trial criteria by a blinded observer. The results of both studies were compared to determ ine the relative accuracy of ultrasound results. Results-Of 130 patients (mean age, 69 +/-8.8 years) who met Doppler ultraso und criteria, 22 (17%) and 8 patients (6%) were found to have 30% to 49% or < 30% stenosis by angiography, respectively. The positive predictive value of carotid Doppler ultrasound for identifying appropriate symptomatic cand idates for carotid intervention (angiographic stenosis greater than or equa l to 50%) was 80%, with a false-positive value of 20%. The positive predict ive value of carotid Doppler ultrasound for identifying appropriate asympto matic candidates for carotid intervention (angiographic stenosis greater th an or equal to 60%) was 59%, with a false-positive value of 41%. Carotid en darterectomy or angioplasty and stent placement were undertaken subsequentl y in 60 (46%) of the patients. In 94 patients who underwent cerebral angiog raphy alone, no complications were observed. Conclusions-The present accuracy of carotid Doppler ultrasound in general p ractice does not justify its use as the sole basis of selecting appropriate patients for carotid intervention. Given the relatively low rate of associ ated morbidity with present day techniques, additional confirmatory studies such as angiography should be performed in every patient before a decision regarding intervention is made.