According to current guidelines, patients with coronary lesions with stenosis <70% should receive optimal secondary prevention drug treatment without angioplasty, even after an acute coronary syndrome (ACS). Nevertheless, coronary angioplasty is rather frequently performed in such situations, presumably because, changes in the atherosclerotic plaque under drug treatment, have remained poorly described so far. Intravascular ultrasound (IVUS) enables a precise description of coronary atheroma, better than the one provided by coronary angiography.