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American Heart Association journal report: All types of chronic infections increase risk of clogged arteries
DALLAS, Feb. 27 - Recurrent ailments as common as sinusitis, bronchitis and even urinary tract infections may increase a person's risk for developing atherosclerosis, the artery-clogging process that causes most heart attacks and strokes, according to a study in today's Circulation: Journal of the American Heart Association.
"Ours is the first study to assess a strong relationship between various types of common chronic infections and atherosclerosis," says Stefan Kiechl, M.D., professor of neurology at Austria's Innsbruck University Clinic, one of several institutions participating in the study.
"A few previous studies have focused on the association between periodontal (gum) disease and the risk of heart attack, but not atherosclerosis," Kiechl says. "Our study provides further strong evidence that chronic infection increases the overall risk of blood vessel disease."
Researchers suspect that one mechanism by which infections promote atherosclerosis is the systemic, or all over, inflammation they are capable of producing. "Among subjects with chronic infections, the risk seemed to be higher in those with a prominent inflammatory response," Kiechl says. "This may indicate that the risk is associated with the toxic effect of the inflammation itself or the body's immune reaction to it."
Austrian and Italian researchers examined changes in the carotid arteries (the main vessels supplying blood to the brain) of 826 men and women, aged 40-79, over five years. The participants were part of the Bruneck Study, a prospective, population-based survey in Bruneck, Italy, that is working to identify factors contributing to the development of atherosclerosis. Researchers gathered information on smoking status, alcohol consumption, socioeconomic status and whether a person had high blood pressure or diabetes.
The team then took blood samples from the individuals and measured levels of inflammatory/inflammation markers such as C-reactive protein (CRP) and other markers.
Of the 826 individuals, 268 had chronic infections. Kiechl says susceptibility to infections increased with advancing age, low social status, and risk behaviors such as cigarette smoking and heavy drinking. He reports that among individuals with chronic infections there was a clear tendency for atherosclerosis risk to increase when CRP levels were higher. CRP levels in people with chronic infections were about three times higher than in those without infection. Other inflammatory markers were also higher in the group with chronic infections.
By the end of the study, 332 (or 41 percent) of the subjects had new plaques in their carotid arteries. Individuals with any chronic infection were nearly three times more likely than those with none to have developed new plaques during the study. Kiechl says the tendency to develop new plaques was strongly associated with the presence of chronic bacteria-caused ailments including respiratory and urinary tract infections. However, infections with herpes zoster virus (responsible for shingles), and chronic active hepatitis B or C (also a virus) appeared to be unrelated to early stage atherosclerosis.
Although the study concentrated on changes in the carotid artery, the researchers also note similar changes in other major blood vessels, including the coronary arteries, where narrowing can trigger heart attacks.
"We believe the principles and main risk factors for atherosclerosis are the same for carotid, coronary and femoral (leg) arteries," he says. "Preliminary results indicate an association between chronic infections and general atherosclerosis, but these analyses are not yet finished and should be interpreted cautiously."
The study produced no evidence that certain types of infections are more risk-related than others. "There was no statistical difference in the level of atherosclerosis risk in subjects with chronic respiratory, urinary, periodontal or other chronic or recurrent infections," Kiechl says.
Data from the Bruneck study may offer new clues for future disease prevention, such as anti-microbial, anti-inflammatory and immune-modulating strategies, Kiechl says. "But at present," he adds, "we don't recommend the non-critical use of antibiotics. All preventive strategies should be tested for efficacy and side effects in controlled intervention trials, some of which are already under way."
Meanwhile, Kiechl advises that people prone to chronic infections should take steps to reduce their other modifiable risk factors for heart disease and stroke. "We would recommend lifestyle modifications for these patients, including smoking cessation, a diet rich in fruits and vegetables, and weight control."
Main investigator in the Bruneck Study was Johann Willeit, M.D. Other researchers include Georg Egger, M.D.; Manuel Mayr, M.D.; Christian J. Wiedermann, M.D.; Enzo Bonora, M.D.; Friedrich Oberhollenzer, M.D.; Michele Muggeo, M.D.; Quingho Xu, M.D., Ph.D.; Georg Wick, M.D.; and Werner Poewe, M.D.
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NR01 - 1260 (Circ/Kiechl)
Media Advisory: Dr. Kiechl can be reached by phone at 43-512-504-3886; or by e-mail at [email protected]. His fax is 43-512-504-4260. (Please do not publish contact information.)
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