The significance of Chlamydia pneumoniae in symptomatic carotid stenosis.

An association between symptomatic carotid stenosis and recent infection with Chlamydia pneumoniae is reported. Thirty-five patients (20 symptomatic and 15 asymptomatic) with carotid stenosis of 70% to 90% underwent carotid endarterectomy. Endarterectomy was performed without patch and shunt; the average occlusion time of the internal carotid artery was 14 +/- 3 min. The atheromatic plaque and a portion of the thyroid artery were examined with polymerase chain reaction and peripheral vein blood was obtained for serologic detection of systematic infection, and IgG and IgM antibodies to C. pneumoniae by enzyme-linked immunosorbent assay. Twenty of 35 patients (57.1%) had increased titers of IgG antibodies to C. pneumoniae. Eight patients revealed IgG plus IgM antibodies; two of the eight had IgG, IgM, and positive findings on polymerase chain reaction. No C. pneumoniae was detected on the thyroid arteries. Sixty-five percent (13/20) of the patients with increased IgG antibodies to C. pneumoniae, 87.5% (7/8) with IgG + IgM, and 100% with IgG + IgM + positive polymerase chain reaction were symptomatic. Plaque morphology in association with symptoms did not reveal a significant correlation between soft plaques and symptoms, whereas the majority of the symptomatic patients had plaques of type III-V. Patients having recent contamination and positive polymerase chain reaction had a significant relationship between C. pneumoniae infection and symptomatic carotid disease. This supports the hypothesis that C. pneumoniae infection can produce a kind of instability of the carotid plaque. The results of this study demonstrate that patients with advanced atherosclerotic carotid disease have an increased incidence of C. pneumoniae infection. Recent infection could be responsible for instability of the carotid plaque, causing cerebral ischemic episodes.