Although patients had full treatment of acute coronary syndrome with STEMI--revascularization by primary PCI (PCI was succesful in 97.5% of patients), ACE inhibitors, beta-blockers and statins were usually administered immediately after PCI, we found a border interaction between I/D ACE polymorphism and signs of LV systolic dysfunction up to 5 days after MI. This evidence concerns the gene ACE and acute coronary syndrome.