Background: Although excellent short- and long-term results have been achieved with surgery in extracranial internal carotid artery stenosis, recurrent stenosis continues to play an important role in post-endarterectomy. Therefore, a close follow-up of patients is warranted. The value of postoperative duplex sonographic evaluations in postoperative follow-up is highly disputed. The study evaluates duplex sonographic parameters as predictors of carotid restenosis, general vascular events and ipsilateral neurological symptoms, in order to assess the role of duplex sonography in follow-up after carotid endarterectomy.
Methods: A retrospective cohort study with a follow-up period ranging from 7 months to 7.5 years was performed in 150 patients who underwent carotid endarterectomy. Pre- and postoperative duplex sonographic and clinical data were analyzed by life-table analysis and multivariate Cox regression with respect to carotid restenosis, vascular and ipsilateral neurological events.
Main findings: Duplex sonographic predictors of carotid restenosis include the postoperative degree of stenosis (residual stenosis > or = 30% or more: relative risk (RR) = 1.56; 1.05-2.32), pre- to postoperative reduction of stenosis (higher than 50%: RR = 0.61; 0.45-0.83), and residual plaques in the operated carotid artery (RR = 1.96; 1.31-2.93). Some of these morphological parameters such as reduction of stenosis are also predictive of vascular events (RR = 1.25; 1.01-1.56) and ipsilateral neurological events (RR = 1.52; 1.05-2.19). In 12 cases restenosis was discovered by duplex sonography and in 3 cases by evaluation of clinical symptoms. In 5 cases restenosis was treated by repeat surgery. Contralaterally, progressive or newly developed carotid stenoses were observed in 17 cases, and only 5 were discovered on the basis of clinical symptoms. Fourteen contralateral stenoses required surgery. Overall, 12 patients underwent treatment for stroke prevention on the basis of duplex follow-up findings (8% of the study population).
Conclusions: Postoperative duplex sonography allows for the identification of patients at risk for carotid restenosis as well as those at risk for other vascular events. As expected, regular examinations permit early detection of restenosis requiring surgical treatment. However, a large number of contralateral stenoses requiring surgical treatment were detected by routine duplex sonographic examinations. The timing of follow-up intervals may be oriented towards the perioperative outcome of duplex sonography.