Endarterectomy for preventing stroke in symptomatic and asymptomatic carotid stenosis. Review of clinical trials and recommendations for surgical therapy.

BACKGROUND

Multicenter, randomized trials have demonstrated advantages for surgery over medical therapy in both symptomatic and asymptomatic carotid stenosis of greater than 70%. Controversial interpretations of these trials are debated between medical and surgical camps. The goal of this review is to summarize the current state of knowledge in carotid stenosis and the role of surgery and several advances in operative management.

METHODS

Summaries of seven major controlled trials of carotid endarterectomy versus medical therapy are presented along with supportive data from over 90 related publications. Criticisms, deficiencies as well as strengths are offered.

RESULTS

All studies in which trial design, clinical variables, case selection, complication definition, and patient follow-up were well conceived and performed showed statistically significant advantages for surgical therapy within a remarkable short interval of follow-up (less than 3 years). Carotid endarterectomy demonstrated a two to four fold reduction in the late incidence of stroke when compared to optimum medical management (risk factor reduction and initiation of antiplatelet therapy). Reduction in stroke risk over time remains stable in surgically treated patients whereas medically treated patients clearly show progression of stenosis and evolution of new neurologic events with time. Several studies indicate that diabetes is a risk factor for stroke with medical therapy that is eliminated by surgical therapy. Advantages were more clearly demonstrated when symptomatic patients (TIAs, stroke, or amaurosis) were studied, but asymptomatic patients received significant benefit as well. The degree of benefit measured was in direct balance to the perioperative risk. Perioperative stroke and death rates must be low (less than 3% combined for asymptomatic patients) in order for statistically significant differences to be detected. However, most centers now can perform carotid endarterectomy within these outcome parameters.

CONCLUSIONS

Randomized trials support the safety and efficacy of carotid endarterectomy for stenosis greater than 70% (with or without symptoms). Advantages of surgery over medical therapy were found in less than three years and there is ample evidence to suggest that the differences between these groups would have been even more pronounced had longer follow-up been obtained. Thus for patients who face many years of risk after diagnosis of a carotid lesion, early surgery is the most important and effective intervention for preventing stroke. The results of these trials raised initial concern over increasing health care expenditures from rising surgical case volumes. However, studies of cost effectiveness confirmed that surgery saves health care dollars when compared to the long term care of stroke victims.