The purpose of this study is to look at the heart rate and rhythm information collected daily in Medtronic implantable pulse generators (IPG), implantable cardioverter defibrillators (ICD) and cardiac resynchronization therapy (CRT) devices. The study will gather this information from many patients to see if heart rate or rhythm data can predict the risk of a patient having a medical condition such as stroke.

Inclusion Criteria:

• Subject provides written informed consent and privacy/protection authorization.
• Subjects 65 years of age or older.

OR

• Subjects with age >18 and < 65 years and one of the following stroke risk factors:
• Prior stroke or TIA
• Diagnosis of hypertension (HTN)
• Diagnosis of Diabetes Mellitus (DM)
• Diagnosis of Congestive Heart Failure (CHF)
• Subjects who meet the Class I/Class II indications for a dual chamber implantable pulse generator or dual chamber implanted cardioverter defibrillator device

OR

• Subjects who meet the criteria for indication of a dual chamber resynchronization device with bi-ventricular pacing (moderate to severe CHF symptoms [NYHA Class III-IV] despite optimal medical therapy, left ventricular ejection fraction ≤ 35%, and a QRS duration ≥130 ms)13.

Exclusion Criteria:

• Subjects who are to receive a replacement IPG, ICD or CRT device.
• Subjects with chronic (permanent) AT/AF.
• Subjects with a history of AV nodal dependent arrhythmias.
• Subjects with a terminal illness who are not expected to survive more than 6 months.
• Subjects who are unwilling or unable to cooperate or give written informed consent and privacy/protection authorization, or subjects whose legal representatives or legal guardians refuse to give informed consent or privacy/protection authorization.
• Subjects currently receiving treatment in another drug and/or device study which could affect the outcome of the trial.
• Subjects who are or will be inaccessible for follow-up at a qualified study center.