International guidelines support the use of a full-dose heparin (anticoagulants) during coronary intervention. However, a lower dose of heparin may be adequate, thanks to advances in angioplasty techniques and the widespread use of pretreatment with two antiplatelet agents.

Thus the investigators designed a study comparing safety and efficacy of standard dose heparin (100 UI/Kg) versus low-dose (50 UI/Kg) in patients undergoing coronary angioplasty who are on aspirin and clopidogrel at the time of the procedure.

• Patients undergoing coronary angioplasty will be randomised to standard vs. low-dose heparin. the study will include "all-comers" (patients with either stable angina or acute coronary syndromes); only patients with ST-elevation myocardial infarction will be excluded.
• An ACT (activated clotting time) will be performed after the initial bolus of heparin: for the standard dose group the target ACT will be > 300 sec. (as recommended by guidelines) while for the low-dose the target ACT will be > 180 sec.

Aim of the study is to show equivalence in ischemic events between the two doses of heparin, in order to confirm the safety of lower dose of heparin in contemporary coronary interventions.

Inclusion Criteria:

• Stable angina, unstable angina or Non-ST elevation myocardial infarction undergoing coronary angioplasty.
• Mandatory pretreatment with aspirin and clopidogrel

Exclusion Criteria:

• ST elevation myocardial infarction
• Coronary interventions with rotational atherectomy
• Coronary interventions on chronic total occlusions (CTO)