The ELECTRA-SIRIO 2 study is a randomized, multicenter, double-blind, investigator-initiated clinical trial aimed to evaluate safety and efficacy of two ticagrelor-based de-escalation antiplatelet strategies in patients with acute coronary syndrome (ACS). During the hospitalization due to ACS, participants will be randomized in a 1:1:1 ratio into one of three arms: low-dose ticagrelor with aspirin (LDTA), low-dose ticagrelor with placebo (LDTP), and standard-dose ticagrelor with aspirin (SDTA), the latter being the control arm. Up to day 30, all enrolled patients will receive standard-dose ticagrelor (2x90mg) + aspirin (1x100mg). Starting from day 31 LDTA and LDTP patients will receive low-dose ticagrelor (2x60mg) + aspirin (1x100mg), SDTA - continuation of previous treatment. Starting from day 91 LDTP patients will receive low-dose ticagrelor (2x60mg) + placebo, SDTA and LDTA - continuation of previous treatment. The aim of the study is to evaluate the influence of ticagrelor maintenance dose reduction from 2x90mg to 2x60mg with or without continuation of aspirin versus dual antiplatelet therapy with standard dose ticagrelor in reducing clinically relevant bleeding and maintaining anti-ischemic efficacy in ACS patients.

Inclusion Criteria:

• diagnosis of STEMI or NSTEMI or unstable angina

• for patients with STEMI, the following three inclusion criteria will have to be met: 1) new ST-elevation at the J-point in two contiguous leads with the cut-point ≥1 mm in all leads other than leads V2-V3, where the following cut-points apply: ≥2mm in men ≥40 years; ≥2.5 mm in men <40 years, or ≥1.5 mm in women regardless of age; or a new left bundle-branch block 2) the intention to perform primary PCI 3) detection of a rise and/or fall of cardiac troponin values with at least one value above the 99th percentile upper reference limit

• for patients with NSTEMI or unstable angina, at least two of the following three criteria will have to be met:

  1. symptoms indicating myocardial ischaemia
  2. ST-segment changes on electrocardiography indicating myocardial ischaemia
  3. detection of a rise and/or fall of cardiac troponin values with at least one value above the 99th percentile upper reference limit in addition to at least one of the following:
  1. ≥60 years of age;
  2. previous MI or coronary artery by-pass grafting;
  3. ≥50% stenosis in ≥2 coronary arteries;
  4. previous ischaemic stroke or transient ischaemic attack;
  5. ≥50% carotid stenosis or cerebral revascularisation;
  6. diabetes mellitus;
  7. peripheral artery disease;
  8. chronic kidney disease with glomerular filtration rate <60 mL/min.

Exclusion Criteria:

• contraindications to ticagrelor or/and aspirin
• indications for oral anticoagulation therapy
• second or third grade atrio-ventricular block
• previous stent thrombosis on treatment with ticagrelor
• end stage kidney disease with glomerular filtration rate <15 mL/min or on haemodialysis
• administration of prasugrel during the index event
• pregnancy