The purpose of this study was to determine if Irbesartan compared to Placebo would reduce the risk of vascular events such as heart attack, stroke, non-cerebral thromboembolic event and death in patients with Atrial Fibrillation (AF) and with at least one major risk of vascular events.

ACTIVE I was one of the 3 separate but related trials of the ACTIVE program conducted in AF patients at risk of vascular events.

Patients were enrolled first into one of the 2 parallel trials of the ACTIVE program evaluating Clopidogrel:

• ACTIVE A comparing clopidogrel + acetylsalicylic acid (ASA) and ASA alone
• ACTIVE W comparing clopidogrel + ASA and oral anticoagulant (OAC).

Then those satisfying additional criteria related to blood pressure and angiotensin receptor blocking agents were re-randomized in the two ACTIVE I arms according to a separate randomization list.

Inclusion Criteria:

Should fulfill the eligibility criteria for ACTIVE A or ACTIVE W trial and:

• have a systolic blood pressure of at least 110 mmHg
• not already receiving an angiotensin receptor blocking agent, unless they are willing and able to be changed to another antihypertensive agent
• no previous intolerance to angiotensin receptor blocking agents
• no proven indication for angiotensin receptor blocking agents, unless an Angiotensin Converting Enzyme (ACE) inhibitor can be substituted

Exclusion Criteria:

Patients will be excluded from ACTIVE study if any of the following are present:

• requirement for clopidogrel (such as recent coronary stent procedure)
• requirement for oral anticoagulant (such as prosthetic mechanical heart valve)
• prior intolerance to acetylsalicyclic acid (ASA) or clopidogrel
• documented peptic ulcer disease within the previous 6 months
• prior intracerebral hemorrhage
• significant thrombocytopenia (platelet count <50 x 10(9)/L)
• psychosocial reason making study participation impractical
• geographic reason making study participation impractical
• ongoing alcohol abuse
• mitral stenosis
• pregnant or nursing woman or woman of child bearing potential and not on effective birth control for at least one month prior to start of study or not willing to continue on birth control for duration of study
• severe comorbid condition such that the patient is not expected to survive 6 months
• patient currently receiving an investigational pharmacologic agent
• requirement for chronic (> 3 months) non-cyclooxygenase-2 (non-COX-2) inhibitor nonsteroidal anti-inflammatory drug (NSAID) therapy unless willing enrolled in ACTIVE A