Association between angiographic evidence of coronary artery disease and seropositivity for Helicobacter pylori and Chlamydia pneumoniae infection.

n 1970, experimental infection of gram-free chickens with an avian herpes virus was found to produce arterial disease that resembled human atherosclerosis. From that time several studies were done on Helicobacter pylori (H. pylori) , Chlamydia pneumoniae (Ch. Pnemoniae), cytomegalovirus1 and periodontal infections, which had different results. In 1994, Mendall et al2 reported for the first time an association between H. pylori infection and coronary artery disease (CAD). After that, several studies were performed which confirmed Mendall's theory3 while some rejected the theory.4 Several studies have provided evidence for a causal relationship between H. pylori and CAD. It has been hypothesized that H. pylori-associated chronic inflammation of the gastric mucosa leads to elevated plasma levels of fibrinogen, C-reactive protein and leukocytes. Other hypotheses include gastritis induced vitamin B-12 deficiency, leading to hyperhomocysteinanemia. The suggested mechanism for Ch. pneumoniae is the direct effect of this microorganism on the intima of vessels.5 Despite many studies, which have been performed to prove the association between the causative role of H. pylori and Ch. pneumoniae in atherosclerosis, there are still many controversies which remain. Two problems are observed in many of the studies, which has been carried out up to now. Firstly, only half of the studies, CAD was proved by angiography while in the other half, CAD was diagnosed by other means such as history, electrocardiogram or other non-reliable diagnostic tests. The other problem was the lack of homogeneity in the population selected for the studies. Socioeconomic level is one of the important factors that is related to both CAD risk factors and the incidence of H. pylori and Ch. pneumoniae infection and this factor was not foreseen in many of the studies. In this study, we investigated the seroprevalence of H. pylori and Ch. pneumoniae infection in patients with proved CAD and in normal population. The population selected for the study I were 207 males and females between 20-80 years old (mean age of 56 years old) who were referred to the angiography division of Namazi Hospital and Saadi Hospital (2 major hospitals) in Shiraz, Southern Iran. These patients were divided into 66 normal patients and 141 patients with CAD according to angiography results. Patients with CAD were defined as having one, 2 or 3 vessels disease, according to the number of arteries affected. Letter of consent was filled by the patients for blood sampling and all were interviewed by means of a structured questionnaire including age, educational status, family history of myocardial infarction, history of cigarette smoking, history of alcohol consumption, history of hypertension, history of hyperlipidemia, history of diabetes, history of gastrointestinal symptoms and history of drugs. From the patients, 10 cc of non-fasting blood sample were drawn from each patient and centrifuged. Sera were stored in -70OC. After collection of the samples, the frozen sera of the patients and controls were simultaneously investigated for H. pylori specific immunoglobulin G (IgG) by an enzyme linked immunosorbent assay (ELISA) (Genesis HpG screen ELISA kit). Manufacturer’s recommended cut-off point is 6.25 μg/ml, which in a Caucasian population provides a sensitivity of 91% and a specificity of 100%. Chlamydia pneumoniae IgG titer was measured by ELISA (IBL). Manufacturer’s recommended cut-off point is 10 U, which in Caucasian population provides a sensitivity of 96% and a specificity of 97.1%. Two hundred and seven patients participated in the study including 130 males (62.8%) and 77 females (37.2%). The mean age of the participants was 56 years old (maximum age was 80 years old and minimum age was 20 years old). Out of the 207 patients who participated in this study, 66 patients (31.9%) had normal angiography without evidence of CAD and 141 patients (68.1%) had CAD. Of the 141 patients with CAD, 45 patients (31.9%) had one vessel disease, 37 patients (26.2%) had 2 vessels disease, 53 patients (37.6%) had 3 vessels disease and 6 patients (4.3%) had 4 vessels disease. Out of the 207 patients who participated in this study, 25 patients (12.1%) were H. pylori seronegative and 182 patients (87.9%) were H. pylori seropositive. Fifty-eight out of 66 patients (87.9%) with normal angiogram and 124 of 141 patients (87.9%) with abnormal angiogram were H. pylori seropositive [odds ratio (OR) of 1.006, 95% confidence interval (CI) of 0.411 2.465, p value with fisher‘s exact test = 1]. Comparing the extent of CAD with H. pylori seropositivity showed that, 42 of 45 patients (93.3%) with one vessel disease, 33 of 37 patients (89.2%) with 2 vessels disease, 44 of 53 patients (83.0%) with 3 vessels disease and 5 of 6 patients Association between angiographic evidence of CAD and seropositivity for H. pylori and C. pneumoniae infection