The aim of the study is the evaluation of the effect of metformin among the patients without diabetes, on the incidence of reintervention, unplanned revascularization, after full percutaneous coronary revascularization as a result of the first episode of the acute coronary syndrome (ACS).

Inclusion Criteria:

• Age >18 years
• ACS, according to the current definition of the European Society of Cardiology, treated with percutaneous coronary intervention with drug eluting stent implantation
• Occupation and place of residence not causing difficulties in participating in control visits
• Uncomplicated course of the disease (ACS) as assessed by the treating physician
• Negative history of diabetes
• Not taking any hypoglycaemic drugs prior to hospitalization immediately or within the last 6 months
• HbA1c< 6,5% (assessment during hospitalization)
• Written consent to participate in the study

Exclusion Criteria:

• Significant valve disease confirmed by ECHO
• Previous CABG
• NYHA IV during hospitalization
• Chronic kidney disease with GFR <60 ml / min / 1.73 m2 according to MDRD
• ALT three times above normal according to laboratory criteria
• Serious co-morbidities and estimated survival less than 2.5 years, as assessed by the treating physician
• Known gastrointestinal disease that may potentially be responsible for the intolerance to metformin (e.g. inflammatory bowel disease, gastro-oesophageal reflux disease)
• Known potential difficulties in cooperation with patients (dementia, mental disorders, distance from the place of residence, if considered potentially problematic, alcoholism)
• Hypersensitivity to metformin
• Pregnancy and breastfeeding
• Patient participation in another clinical trial