Chlamydia pneumoniae and atherosclerosis following carotid endarterectomy

Background: Seroepidemiological studies have shown an association between raised antibody titres against Chlamydia pneumoniae, and carotid atherosclerosis or stroke. However, direct evidence for a causal link between arterial infection with C. pneumoniae and carotid disease remains weak. We hypothesized that long-term follow-up of patients with pathologically-proven arterial C. pneumoniae infection might provide further insight into the role of C. pneumoniae in carotid atherosclerosis. Methods: We followed a cohort of 70 carotid endarterectomy patients for ipsilateral restenosis, contralateral progression, and all-cause mortality (four year median follow-up period). All patients had presence or absence of C. pneumoniae in their carotid plaques documented by immunohistochemistry after endarterectomy. A survival function was generated and the log-rank test was used to assess the difference in survival between subjects with and without documented chlamydial infection in their plaque. Results: Baseline demographic and cardiovascular risk factors were similar between the two groups, and survival analysis demonstrated no difference (p>0.05) in all-cause mortality, or all-cause mortality combined with restenosis and progression. Conclusions: Our data finds no causal role for C. pneumoniae in restenosis or progression of carotid disease or mortality in this patient population with advanced carotid atherosclerosis.