This observational study will based on the Register of Information and Knowledge About Swedish Heart Intensive Care Admissions (RIKS-HIA) and the Swedish Coronary Angiography and Angioplasty Registry (SCAAR) which since 2009 are merged into The Swedish Web-system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies (SWEDEHEART).

The aim of this study is to investigate the impact of different antithrombotic treatment options (treatment duration, type of treatment and combination of treatments) in Acute Coronary Syndrome (ACS) patients on outcomes such as recurrent ischemic events and mortality.

Inclusion Criteria:

• Patient with an event of ACS under the study period
• Patient found in the National Registry of Drug Prescriptions and treated or not treated with antithrombotic drug/s (acetylsalicylic acid and/or either clopidogrel/ticlopidine/prasugrel and/or warfarin)

Exclusion Criteria:

• Patients will not be excluded from the database if they fulfill inclusion criteria.

Patients previously enrolled into the SWEDEHEART (RIKS-HIA/SCAAR/SEPHIA) registry from 1 Jan 2006 to 1 July 2010 with an event of ACS and observed during the index hospitalization following enrollment.