Reflex alterations of cardiac autonomic modulation have been described after acute myocardial infarction (AMI). The non-homogeneous autonomic innervation of the heart gives reason of different patterns of autonomic modulation depending upon the site of AMI. Conflicting data are available on cardiac autonomic modifications after primary percutaneous coronary intervention (pPCI). We evaluated cardiac autonomic changes in patients with ST-elevation myocardial infarction (STEMI) after pPCI, either within 24h after revascularization (T0) and at clinical stability (T1, 6±2days), taking into account the site of infarction.