In a prospective randomised study design to investigate, if a systematic risk factor screening for bleeding ulcer in patients, who following percutaneous coronary intervention (PCI) commence a one year combination treatment with low dose aspirin and clopidogrel, followed by prophylactic treatment with a proton pump inhibitor (PPI) in case of increased risk, can reduce the risk of bleeding ulcer. Based on the recently raised suspicion that PPI's, possibly except pantoprazole, reduce the effect of ADP-receptor inhibitors, pantoprazole has been chosen as prophylaxis in the screening group, and analyses will be done to ascertain whether PPI treatment increases the risk of coronary events. Further analyses will be made to see whether PPI prophylaxis in high risk patients can increase compliance with the antithrombotic treatment through a reduction of side effects, thereby reducing the risk of myocardial infarction in particular stent thrombosis. The study population will be analyzed further to identify the patients, who will benefit the most from PPI prophylaxis Hypothesis: screening heart patients for risk factors for bleeding ulcer and subsequently treating high risk patients with PPI can reduce the incidence of bleeding ulcer and increase compliance with the antithrombotic treatment; thereby possibly reducing the risk of coronary events and improving survival. Initial a description of the prevalence of risk factors will be done.

Inclusion Criteria:

• Patients who has had a PCI with stenting or balloon dilatation in the cardiology department at Odense University Hospital, Århus University Hospital and Ålborg Sygehus, where subsequent treatment with low-dose aspiring and clopidogrel or another thienopyridine is planned for one year.

Exclusion Criteria:

• previous PCI with stenting or balloon dilatation
• treatment with clopidogrel prior to PCI
• lack of informed consent