Helicobacter pylori Infection and the Risk for Heart Attacks in Men

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The summary below is from the full report titled "A Prospective Study of Helicobacter pylori Seropositivity and the Risk for Future Myocardial Infarction among Socioeconomically Similar U.S. Men." It is in the 7 August 2001 issue of Annals of Internal Medicine (volume 135, pages 184-188). The authors are PM Ridker, J Danesh, L Youngman, R Collins, MJ Stampfer, R Peto, and CH Hennekens.

What is the problem and what is known about it so far?

Heart attacks result when blockages form in the arteries that supply blood to the heart (the coronary arteries). Chronic infection with certain bacteria may be among the many factors that contribute to these blockages, possibly by causing inflammation of the blood vessel walls, which damages the walls and allows blockages to form. Chronic infections like this do not cause people to feel sick but can be detected using blood tests that tell whether the person has been exposed to the infection in the past. Helicobacter pylori (H. pylori) is a type of bacteria that appeared to be associated with coronary artery disease in some (but not all) previous studies; however, those studies could not prove whether the H. pylori infection came before or after the heart disease. Moreover, although H. pylori infection is very common in general, it is most common in people who are poor. In past studies, it was unclear whether heart disease was associated with H. pylori infection itself or other risk factors for heart disease that are more common among people who are poor.

Why did the researchers do this particular study?

To find out whether previous exposure to H. pylori infection is associated with future development of heart attacks among a group of U.S. men with similar social and economic status.

Who was studied?

890 male doctors selected from the 22,071 doctors who participated in the Physicians' Health Study, a large study designed to see whether aspirin and beta-carotene (a vitamin) can prevent heart disease. Of the 890 selected doctors, 445 had had heart attacks during the course of the Physicians' Health Study and 445 had remained free of cardiovascular disease.

How was the study done?

At the time they entered the Physicians' Health Study, the doctors who participated gave blood samples that were stored for future testing. The researchers tested these stored blood samples for evidence of previous H. pylori infection.

What did the researchers find?

Of the men who had heart attacks, 43.4% had evidence of previous H. pylori infection compared with 44.3% of the men who did not have heart attacks. The similar frequency of infection in both groups does not suggest a strong association between H. pylori infection and heart attacks.

What were the limitations of the study?

The study cannot rule out a weak association between previous H. pylori infection and heart attacks. Since the study included only male physicians, the results may not apply to other groups of people.

What are the implications of the study?

The association between H. pylori infection and future heart attack is not strong among men with similar socioeconomic status.