The incidence of ADRs was 8.6%, and the incidence of serious ADRs was 3.4%. The highest incidence of ADRs was for gastrointestinal disorders (3.3%). Most of the ADRs and serious ADRs were bleeding AEs. A total of 12 patients experienced major bleeding AEs. Approximately 60% (seven patients) of all major bleeding AEs were gastrointestinal disorders. This finding was consistent with the observation in a survey of clopidogrel (J-PLACE) in NSTEMI/unstable angina pectoris patients scheduled to undergo PCI , which suggests that gastrointestinal disorders are the main bleeding AEs in ACS patients. Therefore, preventive measures for gastrointestinal disorders might be required. Aspirin is highly likely to be a contributor to the development of these gastrointestinal disorders  and the prevention of low-dose aspirin-associated upper gastrointestinal injuries by proton pump inhibitors (PPIs) has been reported . However, in this study, the proportion of patients receiving PPIs was less than half (47.4%) of the total population assessed. Although no significant difference was noted in the incidence of bleeding AEs between patients treated with or without concomitant PPIs in this study, concomitant use of PPIs from the start of dual anti-platelet therapy seems essential for preventing gastrointestinal disorders, especially in high-risk patients.