Introduction: Patients with atrial fibrillation (AF) have a substantial risk of stroke and systemic embolism. Subclinical AF is often suspected to be the cause of stroke in these patients. The detection of asymptomatic AF episodes is a challenge and the real rate of occurrence of these episodes remains unknown. The rate of stroke is high among patients who have received a pacemaker and this device can detect subclinical episodes of rapid atrial rate, which correlate with electrocardiographically documented AF. The net benefit of anticoagulant treatment is well established in patients with clinical AF but data about anticoagulation in subclinical AF setting is unknown. The aim of this study is to assess the impact of anticoagulant therapy on subclinical AF, directed by cardiac implantable electronic device (CIED) intensive monitoring, on the incidence of stroke and systemic embolism and correlate the AF episodes detected by CIED with thromboembolic events. Methods: This is a prospective, randomized, unicentric, parallel clinical study in patients with atrioventricular pacemaker, defibrillator, or cardiac resynchronization therapy devices in sinus rhythm and CHADS2 score (an index of the risk of stroke in patients with atrial fibrillation, range from 0 to 6) ≥ 2 . Patients will be randomized to the intervention group - intensive monitoring arm (Group I) or control group - routine schedule arm (Group II) in a 1:1 ratio. Time to inclusion will be 24 months and all patients will be followed up for a period of 36 months. Group I, patients will be submitted to device data collection every 2 months, while in Group II, patients will be managed conventionally. Patients from Group I with episodes of subclinical AF will receive anticoagulant therapy, as well as patients with clinical AF of both arms. Device data from Group II patients will not be analyzed until they achieve the primary endpoint. Primary endpoint: stroke or systemic embolism. Secondary endpoints: subclinical AF rate, total mortality, cardiovascular mortality, myocardial infarction, cardiovascular hospitalization, and bleeding rates. Expected outcome: It is expected that anticoagulation therapy of subclinical AF directed by CIED intensive monitoring will reduce the incidence of stroke and systemic embolism comparing to patients with non-diagnosed subclinical AF.

Patients with atrial fibrillation (AF) have a substantial risk of stroke and systemic embolism. Subclinical AF is often suspected to be the cause of stroke in these patients. The detection of asymptomatic AF episodes is a challenge and the real rate of occurrence of these episodes remains unknown. The rate of stroke is high among patients who have received a pacemaker and this device can detect subclinical episodes of rapid atrial rate, which correlate with electrocardiographically documented AF. The net benefit of anticoagulant treatment is well established in patients with clinical AF but data about anticoagulation for subclinical AF settings is unknown. The aim of this study is to assess the impact of anticoagulant therapy on subclinical AF, directed by cardiac implantable electronic device (CIED) intensive monitoring, on the incidence of stroke and systemic embolism and correlate the AF episodes detected by CIED with thromboembolic events. Methods: This is a prospective, randomized, unicentric, parallel clinical study in patients with an atrioventricular pacemaker, defibrillator, or cardiac resynchronization therapy devices in sinus rhythm and CHADS2 score (an index of the risk of stroke in patients with atrial fibrillation, range from 0 to 6) ≥ 2 . Patients will be randomized to the intervention group - intensive monitoring arm (Group I) or control group - routine schedule arm (Group II) in a 1:1 ratio. Time to inclusion will be 24 months and all patients will be followed up for a period of 36 months. Group I, patients will be submitted to device data collection every 2 months, while in Group II, patients will be managed conventionally. Patients from Group I with episodes of subclinical AF will receive anticoagulant therapy, as well as patients with clinical AF of both arms. Device data from Group II patients will not be analyzed until they achieve the primary endpoint. Primary endpoint: stroke or systemic embolism. Secondary endpoints: subclinical AF rate, total mortality, cardiovascular mortality, myocardial infarction, cardiovascular hospitalization, and bleeding rates. Expected outcome: It is expected that anticoagulation therapy of subclinical AF directed by CIED intensive monitoring will reduce the incidence of stroke and systemic embolism comparing to patients with non-diagnosed subclinical AF.

Inclusion Criteria:

• Age >= 18 years
• CHADS2 score >=2
• Sinus rhythm
• Cardiac Implantable Electronic Device

Exclusion Criteria:

• Atrial fibrillation
• Severe heart valve disease
• Anticoagulation therapy
• Pregnancy