Numerous genetic and environmental factors are thought to be responsible for the development of atherosclerosis, but the role of pathogens in this process remains unclear. In January 1 Circulation, Christine Espinola-Klein and colleagues at the Johannes Gutenberg University Mainz, Germany, demonstrated a strong association between viral and bacterial pathologic burden and the extent of atherosclerosis (Circulation 2002, 105:15-21).
Espinola-Klein et al. analyzed the presence and extent of peripheral artery disease in 572 patients admitted for diagnostic heart catheterization. All participants underwent coronary angiography and were classified into three groups: control (normal coronary, carotid, and leg arteries); limited disease (at least one coronary artery stenosis detected but with normal leg arteries); or, advanced atherosclerosis (patients had coronary artery disease and/or leg artery stenosis). Exposure to IgG or IgA antibodies to herpes simplex virus 1 and 2 (HSV I, II), cytomegalovirus (CMV), Epstein-Barr virus, Haemophilus influenzae, Chlamydia pneumoniae, Mycoplasma pneumoniae, and Helicobacter pylori was also measured.
A significant association was noted between the number of infectious pathogens to which patients had been exposed and the extent of atherosclerosis. The accompanying odds ratio ranged from 1.8 for patients seropositive to four to five pathogens to 2.5 for patients seropositive to six to eight.
A correlation was also found between mortality rate and the number of seropositivities; after a mean 3.2 years follow up, cardiovascular mortality was 7% and 20% in patients with advanced atherosclerosis and seropositivity for zero to three, and six to eight pathogens, respectively. Notably, following adjustments for age, sex, risk factors, and C-reactive protein, only IgA seropositivity for C. pneumoniae, and elevated antibodies to H. pylori, CMV, and HSV-2 were independently associated with advanced atherosclerosis.
Espinola-Klein et al. concluded that while it is unlikely that one specific pathogen increases atherosclerosis risk, increasing numbers are associated with both disease extent and long-term prognosis.