AIMS: Previous studies suggested an association between infection by cytotoxic CagA-positive Helicobacter pylori strains and atherosclerotic stroke. It has been hypothesized that CagA strains could increase the risk for stroke by affecting carotid plaque irregularity. Our aims were: (1) to confirm the association between CagA strains and atherosclerotic stroke, and (2) to assess the association between CagA strains and carotid plaque irregularity. METHODS AND RESULTS: We enrolled 105 consecutive patients affected by atherosclerotic stroke and 130 sex, age, social background-matched controls without relevant vascular diseases. Risk factors for atherosclerotic stroke, H. pylori infection and CagA status were evaluated in all subjects. The ...