The Investigators will test the hypothesis that nonselective beta-blockers would have a more pronounced effect on platelet aggregation than selective beta-blockers in patients with acute coronary syndrome treated with dual anti platelet therapy.

In patients with acute coronary syndrome (ACS) beta-blockers are recommended for secondary prevention. It is known that catecholamine levels can potentiate platelet reactivity and beta-blocking agents may also affect platelet aggregation. This effect is mainly mediated by adrenergic receptors on platelets. This suggests that nonselective beta-blockers would have a more pronounced effect on platelet aggregation than selective beta-blockers. However, little is known about the effect of beta-blockers on platelet aggregation in patients with cardiovascular disease and, to date, nothing is known in the setting of ACS.

The aim of the present study is to evaluate the effect of selective and nonselective beta-blockers on platelet aggregation in ACS patients treated with dual anti platelet therapy.

Inclusion Criteria:

• Acute Coronary Syndrome
• Current dual anti platelet treatment with acetylsalicylic acid and Ticagrelor

Exclusion Criteria:

• ongoing prasugrel, ticlopidine or clopidogrel therapy
• Creatinine Clearance < 30 ml/min/1.73mm2
• Moderate to severe anemia Hemoglobin < 10 mg/dl
• Platelet count >600000/mm3 or <150000/mm3 or hematocrit >50% or <25%
• concomitant neoplastic or immune-mediated pathologies
• severe pulmonary pathologies
• contraindication to beta blocker therapy.