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American Heart Association journal report: Ulcer-causing bacteria also may be associated with heart disease
DALLAS, May 5 -- Infection by a particularly strong strain of bacteria normally associated with stomach ulcers could be a contributing factor to heart disease, according to a report in today's Circulation: Journal of the American Heart Association.
Italian researchers report they have found that the association between the bacteria -- known as Helicobacter pylori (h. pylori) -- and heart disease appeared to depend on the strength, or virulent nature, of the bacteria strain.
In their study, the researchers found evidence of the bacteria in 62 percent of people with heart disease and only 40 percent of those without the disease.
"The prevalence of infection by Helicobacter pylori was similar in patients with heart attack, unstable chest pain, or chronic chest pain," says the study's lead author, Vincenzo Pasceri, M.D., of the department of internal medicine and cardiology at the Catholic University of the Sacred Heart in Rome.
"The findings strongly suggest that the association between Helicobacter pylori and heart disease is related to the strength of this bacteria," he says.
Though there was a relationship between the bacteria and heart disease, the researchers stated that h. pylori -- which can be controlled with antibiotics -- did not exacerbate the severity of heart disease.
The researchers studied 88 patients who had ischemic heart disease, which causes heart attacks and is the result of poor blood flow to the heart. The control group consisted of 88 patients who did not have heart disease. Researchers say every effort was made to match the groups by body mass index -- a measure of fatness -- and socioeconomic class. The latter was important, Pasceri says, because poorer people tend to get more infections than those with more financial resources.
Even with this finding, Pasceri says that an individual with an ulcer because of an h. pylori infection shouldn't necessarily be examined for heart disease.
"Screening for heart disease in patients with an ulcer is not a cost-effective strategy, although, of course, patients should be treated for h. pylori infection to heal their ulcer," says Pasceri. "Our results, which show that the risk of heart disease is due only to virulent strains, allow us to treat patients really at risk, enhancing the cost-benefit ratio of the treatment."
The key factor seemed to be whether the bacteria contained a gene called CagA. Heart disease affected 43 percent of people with the bacteria with the CagA gene, compared to only 17 percent of those infected with bacteria lacking this gene. There was no difference between patients and controls who were infected by the bacteria without the gene.
Pasceri says that further research needs to be done to determine the association between h. pylori and heart disease, but he adds that there is increasing evidence that several chronic infections are associated with the development of atherosclerosis in otherwise healthy people.
"It is worth noting that such infections have a high prevalence both in Europe and the United States," Pasceri says. "Even a small increase in the risk of ischemic heart disease due to these infections would mean a huge number of heart attacks and cardiac deaths. Prevention and treatment of these infections may be a new strategy for the prevention of ischemic heart disease."
H. pylori is one of four organisms often investigated for an association with heart disease. The other three -- including Chlamydia pneumoniae, cytomegalovirus and herpes -- cause low-grade, life-long infections that can produce a smoldering inflammation, the kind that leads to heart disease, according to Paul M. Ridker, M.D., M.P.H, of Brigham and Women's Hospital in Boston. Ridker wrote an editorial accompanying publication of the research.
Several earlier studies suggest an association, but others suggest none. Ridker points out that people with poor access to medical care are more likely to develop infections that are not treated promptly and also more likely to suffer from heart disease. The two may not be related, Ridker says.
Ridker adds that while the data are "provocative and interesting," additional research is needed before any definite link can be shown.
Helicobacter pylori were discovered in 1983 by two Australian researchers. The tiny, spiral-shaped organisms live in the stomachs of most people but occasionally are the cause of gastritis, the underlying condition for stomach ulcers and some forms of cancer.
Co-authors are: Giovanni Cammarota, M.D.; Giuseppe Patti, M.D.; Lucio Cuoco, M.D.; Antonio Gasbarrini, M.D.; Rita L. Grillo, M.D., Giuseppe Fedeli, M.D.; Giovanni Gasbarrini, M.D.; and Attilio Maseri, M.D.
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Media advisory: Dr. Pasceri can be reached by phone at 39 6 301 54187 or by fax at 39 6 305 5535. Dr. Ridker can be reached by phone at (617) 278-0869. (Please do not publish telephone numbers.)
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