The purpose of this study is to determine if an AF detection intervention in men and women at least 70 years of age with undiagnosed atrial fibrillation (AF) or atrial flutter (AFL) reduces the person-years incidence rate of stroke compared to usual care (no AF detection intervention).

This a prospective, randomized study in primary care practices.

Inclusion Criteria:

• Men and women at least 70 years of age who are new or established participants in the primary care practice
• Willing to provide consent to participate in the study and to use personal health information to ascertain endpoints from the Center for Medicare & Medicaid Services (CMS) Medicare Claims Database and to access data from health records
• Health insurance by Medicare Parts A & B (Medicare Fee-for-service)

Exclusion Criteria:

• Oral anticoagulation (OAC) for any indication at the time of enrollment
• History of Atrial Fibrillation (AF) or Atrial Flutter (AFL) as documented in the participant's current medical problem list
• Any condition the investigator considers a contraindication to OAC, e.g., bleeding that required medical attention or severe renal impairment
• Any condition the investigator considers will prevent compliance with study instructions
• Implanted cardiac devices (pacemakers, implantable cardiac defibrillators, or cardiac resynchronization therapy, and implantable loop recorders)
• History of allergy to adhesive
• Not able to wear the Zio®XT monitor or not able to apply the monitor by herself/himself or with the help of a caregiver

Other protocol-defined inclusion/exclusion criteria could apply