Carotid surgery versus medical therapy in asymptomatic carotid stenosis. The CASANOVA Study Group.

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Abstract
The CASANOVA study (Carotid Artery Stenosis with Asymptomatic Narrowing: Operation Versus Aspirin) is a multicenter trial in 410 patients with asymptomatic stenosis (50-90%) of the internal carotid artery who were randomized after angiography. In group A, 206 patients with unilateral and bilateral stenosis had surgery unilaterally or bilaterally, respectively. In group B, 160 patients with unilateral stenosis had no initial surgery, whereas those with bilateral stenosis had surgery on the more affected side. Patients were operated on during the 3-year follow-up period if one of the following events occurred: development of a stenosis exceeding 90%; development of a bilateral internal carotid artery stenosis greater than 50% (operation on the more affected side); transient ischemic attack in the region supplied by the internal carotid artery, together with a stenosis of this artery greater than 50%; development of an internal carotid stenosis greater than 50% contralateral to the operated side or restenosis greater than 50% in group A. All patients were treated with 330 mg acetylsalicylic acid and 75 mg dipyridamole three times daily. The minimal follow-up was 3 years. End points were ischemic neurologic deficit exceeding 24 hours or death due to surgery or stroke. Altogether, 334 carotid endarterectomies were performed. Complications of angiography and operation (6.9%) were included. Statistical analysis found no significant difference in the number of neurologic deficits and deaths between the two groups. Carotid endarterectomy for asymptomatic patients with a stenosis of the internal carotid artery of less than 90% is not recommended at this time except as part of a controlled clinical trial. However, cases of higher grade stenosis (greater than 90%) were excluded from this study and were referred for operation. No conclusion can be rendered regarding the potential benefit of endarterectomy in these higher risk categories.