AVAI: Atrial Ventricular Arrythmia Incidence

Inclusion Criteria: * Patient has been implanted with a St Jude Medical ICD, mono,bicameral or cardiac resynchronization therapy - Defibrillator (CRT-D) according the American College of Cardiology (ACC), American Heart Association (AHA), National Standards for Physical Education (NASPE) guidelines. (min. 24 hours - max. 2 months) * Patient has signed the study specific Informed consent document. * Patient is older than 18 years of age Exclusion Criteria: * Patient has a permanent Atrial Fibrillation * Patient has a documented slow ventricular Tachycardia Episodes previous to the ICD implant. * Patient not programed with a ventricular Tachycardia (VT) zone upper than 120 bpm. * Patient requires cardiac resynchronization * Patient has Brugada Syndrome * Patient has long QT Syndrome * Patient has a device replacement; * Patient is pregnant or nursing * Patient is unable to attend the follow-up visits