Cardiac implantable electronic devices (Implantable Cardioverter Defibrillators (ICD),cardiac resynchronization therapy (CRT)) with sensors have been used to develop Heart Failure diagnostics which indicate early changes leading up to hospitalizations. The study is testing a feature that can help predict when your heart failure is getting worse. The feature is called HeartLogic™ Heart Failure Diagnostic Service, or simply HeartLogic.

The purpose of this study is to determine which treatment is best for preventing stroke or systemic embolism in patients who have experienced at least one episode of SCAF (sub-clinical atrial fibrillation) detected by their pacemaker or ICD (intracardiac defibrillator) or ICM (insertable cardiac monitor) and also have other risk factors for stroke. Subjects will be randomly assigned to one of the two treatment strategies: apixaban or aspirin. Neither the subject nor the researcher will know which treatment the subject is assigned. Follow-up visits will occur every six months until the end of the study.