AbstractINTRODUCTION: Coronary artery disease (CAD) is the main cause of mortality inindustrial and developing countries. New risk factors including infections are underinvestigation as potential factors. One of these infectious agents is Helicobacter pylori,which has been investigated in numerous studies. This study was designed in view of thecontroversies surrounding the impact of Helicobacter pylori on the prognosis of patients withacute coronary syndrome (ACS).METHODS: All patients with ACS including unstable angina and myocardial infarction whowere referred to Fatemieh Hospital between 20 February 2003 and 19 February 2004 andwere admitted to the CCU ward were enrolled in this cohort study. A total of 411 patientswith ACS were evaluated for Helicobacter pylori serologically, and the occurrence of cardiacevents needing angioplasty or coronary surgery was assessed.RESULTS: Mean age of patients was 59.97±38.12 years and 56% of them were male. Theserology test for Helicobacter pylori infection was positive in 45.6±12.38%, negative in43.8%, and borderline in 10.6% of patients. 191 patients had unstable angina and 220patients had myocardial infarction. In a one-month follow-up, 10% of the patients developedcardiac events and PCI or CABG was performed in 6.1% (16.1% totally). One-monthoccurrence of cardiac events in the group with Helicobacter pylori infection was 11.9% vs.19.3% in the group without infection (χ2 =3.078, P=0.079).DISCUSSION: This prospective study showed that Helicobacter pylori infection has noeffect on short term prognosis of patients with ACS.ARYA Journal, 2005, 1(3): 164-169Keywords • Helicobacter pylori • Acute coronary syndrome • Prognosis