Medtronic Genetic Arrhythmia Markers for Early Detection (GAME Study)

Inclusion Criteria: The following criteria apply to all subjects: * Subject has an ICD or CRT ICD implanted * Subject must be on optimal medical therapy * Subject is a Caucasian with all 4 grandparents believed to be Caucasian * Subject has had a myocardial infarction (MI) prior to ICD implantation * Subject is willing and able to comply with the study protocol * Subject is willing and able to sign and date the study Informed Consent and HIPAA Authorization (US) Case Inclusion Criteria: The following criteria apply to case subjects only: * Subject is at least 40 years of age at time of ICD implantation * Subject has at least one documented life-threatening arrhythmia (LTA) on their ICD that can transferred as a save-to-disk or has had an LTA documented in their medical history. LTA is defined as a true VT/VF episode with cycle length less than or equal to 400ms that was terminated by the device. Control Inclusion Criteria: The following criteria apply to control subjects only: * Subject is currently at least 70 years of age * Subject has haad currently implanted Medronic ICD for a minimum of three years Exclusion Criteria: The following criteria apply to all subjects: * Subject has received a bone marrow or heart transplant at any time * Subject has a previously identified cause for arrhythmias (Brugada, LQT, HCM) Control Exclusion Criteria: The following criteria apply to control subjects only: * Subject has had a potentially LTA documented on their ICD * Subject was previously identified as having a LTD at any time in life * Subject has had the memory on their ICD cleared at any time in the past three years.