ST Monitoring to Detect Acute Coronary Syndrome Events in Implantable Cardioverter Defibrillator Patients

Inclusion Criteria: * Eligible patients will meet all of the following: 1. Have an indication for an ICD implantation or pulse generator change 2. Have documented coronary artery disease. Documented coronary artery disease is defined as having at least one of the following present a) evidence of a prior MI on ECG and/or cardiac enzymes, b) prior revascularization (by coronary artery bypass grafting or percutaneous coronary intervention) c) angina and/or ST-T wave abnormalities indicative of ischemia on exercise stress test, nuclear stress test, or echo stress test, or d) coronary artery disease diagnosed by coronary angiography. 3. Willing and able to comply with protocol requirements, including keeping all required visits 4. Willing to participate in the study and able to sign an IRB approved informed consent form 5. Be at least 18 years of age when enrolled in the study Exclusion Criteria: * Patients will be excluded if they meet any of the following: 1. Are pacemaker dependent (defined as a need for ventricular pacing ≥ 20% of the time) 2. Have NYHA Class IV Heart Failure 3. Have persistent or permanent atrial fibrillation 4. Have a known history of intermittent Bundle Branch Block 5. Pregnant or planning a pregnancy during the study participation 6. Have a life expectancy of \< 1 year due to any condition 7. Are currently participating in a clinical investigation that includes an active treatment arm.