The influence of contralateral disease on the natural history of nonoperated significant carotid stenosis.

The influence of contralateral disease on the natural history of ipsilateral nonoperated carotid stenosis greater than 50% was analyzed in 90 carotid arteries imaged by contrast arteriography or duplex scanning with a mean follow-up of 23.6 months. Ipsilateral stenosis was greater than 80% in 24 arteries and 50-79% in 66 arteries. Contralateral disease was present in 30 (Group I) and absent in 60 (Group II) patients. In Group I, the contralateral disease consisted of total occlusion in nine (30%), greater than 80% stenosis in five (17%), 50-79% stenosis in 12 (40%) with a mean of 78.6%. No significant difference existed in the incidence of initially asymptomatic vessels (57% versus 67%), stroke (13% versus 2%), or transient ischemic attack (17% each) between Groups I and II on the ipsilateral side (p greater than .05). New ipsilateral neurologic events occurred significantly more often in arteries with greater than 80% ipsilateral stenosis than those with 50-79% stenosis (p less than .02). The incidence of subsequent ipsilateral neurologic events (37% versus 22%), strokes, or transient ischemic attacks (20% versus 13%) was no different in Groups I and II, respectively (p greater than .05). Combined ipsilateral and contralateral neurologic events occurred significantly more often in patients with contralateral disease (p less than .05). Whereas in Group I, new ipsilateral symptoms were significantly more common in initially symptomatic vessels compared to asymptomatic ones (61.5% versus 17.6%, p less than .04), no such difference existed in Group II.