500 Patients (minimum) will be enrolled following commercial implant. Will be treated by their physicians using the standard of care.

Standard of care for the Guardian includes an in-office initial programming visit 7-14 days following implant and every 6 months.

The purpose of this prospective, non-randomized, single arm, event-based, multicenter trial is to assess: (1) the diagnostic accuracy of the device, (2) the compliance of the prescribing physician, (3) the experience of the implanting physician, (4) the experience of the emergency department physician and (5) the patient compliance for "Emergency" and "See Doctor" alerts. The adequacy of the training program for the prescribing physician, implanting physician, emergency department physician, and patients will be assessed.

A minimum of 500 patients who have had prior ACS events and who remain at high risk for recurrent ACS events will be enrolled in the PAS, for the purpose of accruing 314 adjudicated True Positive (TP) or False Positive (FP) ACS events. These ACS events will contribute to the Positive Predictive Value (PPV) and false positive rate (FPR) endpoints of the study. The PAS will be completed once the 314 ACS events have been collected and adjudicated.

Inclusion Criteria:

• 1. Subject has at least one of the following conditions:

  1. Diabetes (Type I or Type II)

  2. Compromised renal function (Cr > 1.2 mg/dl or creatinine clearance less than 50)

  3. TIMI Risk Score of at least 3

     2. Previously diagnosed with a high-risk acute coronary syndrome (e.g., Unstable Angina, STEMI or NSTEMI) or has undergone or is scheduled for CABG within 6 months of implantation.

     3. Has already undergone coronary angiography and revascularization, unless the physician determines it is appropriate to implant before or during the planned procedure.

     4. Lives in a geographic area in close proximity (within approximately 60 minutes by EMS) to any hospital that can treat AMI.

     5. Subjects (men or women) at least 21 years of age. Women of childbearing age must have a negative pregnancy test or confirmation of one of the following:

  1. Post-menopause or amenorrhoeic during the past year
  2. Surgical sterilization
  3. Use of effective contraceptive method

Exclusion Criteria:

• 1. In the investigator's opinion, subject lacks ability to respond appropriately to alarms, e.g., illiteracy, poor memory or cognitive function, dementia or other condition affecting memory function, etc.

  2. There is known compromised tissue at the site of lead implantation in the apex of the right ventricle, e.g., prior infarct affecting the RV apex location.

  3. A permanent pacemaker or ICD is already in place or the subject is indicated for ICD or pacemaker implantation based on the guidelines published by the American College of Cardiology as Class I and IIa recommendations. Class IIb recommendations are at the investigator's discretion.

  4. Subject cannot feel the IMD vibration when placed on top of the skin on the left pectoral side of the chest.

  5. Subject has recurrent or persistent atrial fibrillation. 6. Subject has recurrent or persistent non-sinus cardiac rhythm, second or third degree atrioventricular blocks, QRS duration greater than 120 ms, Benign Early Repolarization (BER), Brugada Syndrome (LLB, BBB, RBB) or Rate Induced BBB.

  7. Subject has left ventricular hypertrophy evidenced by EKG criteria. 8. Subject has any condition preventing the subcutaneous implantation of the Guardian® System in a left pectoral pouch, such as: superior vena cava thrombosis, subcutaneous tissue deemed inappropriate for the procedure or prior central venous access via portacath, Hickman, Groshong, or similar placed in a left pectoral location or left side PICC line.

  9. Subject has extremely heavy alcohol consumption (participates in binge drinking that leads to alcohol intoxication) or has history of alcohol or illicit drug abuse within past 5 years.

  10. There is evidence of unresolved infection (fever > 38o C and/or leukocytosis > 15,000).

  11. Subject has history of bleeding disorders or severe coagulopathy (platelets < 100,000 plts/ml; APTT or PT > 1.3 x reference range).

  12. Subject has had a hemorrhagic stroke or transient ischemic attack (TIA) in the past 6 months.

  13. Subject has a potentially fatal disease, such as cancer or refractory congestive heart failure, associated with limitation of life expectancy, which may lead to inadequate compliance to the protocol or confusing data interpretation.

  14. Subject has clinical conditions such as heart diseases, difficult-to-control blood pressure, difficult-to-control insulin-dependent diabetes or serious prior infections attributed to the diabetes, or others that, at the investigator's discretion, could seriously affect the subject's current clinical condition during study procedures.

  15. Subject has previously been implanted with an AngelMed Guardian® System, current participation or previous participation in another drug or device study in the past 30 days that conflicts with this study as determined by the study sponsor.

  16. Subject has experienced gastro-intestinal hemorrhage in the past 6 months. 17. Subject has any situation in which the use of aspirin is contraindicated for at least 6 months.

  18. Subject has epilepsy. 19. Subject has known severe allergies, e.g., peanut, bee sting, etc. 20. Subject has a known coronary occlusion that cannot be reperfused e.g. known multiple small vessel disease, saphenous vein graft, prior angiography where doctor could not intervene, or jailed occlusion.

The study population includes patients who have had prior ACS events and who remain at high risk for recurrent ACS events. Patients will be identified by implanting physicians using standard of care requirements for elective commercial implants based on the appropriate labeling and indications for use of the AngelMed Guardian System.

The study doctor will collect your personal and medical information. For example:

• Past and present medical records
• Research records
• Records about phone calls made as part of this research
• Records about your study visits

Your information may be given to:

• The U.S. Food and Drug Administration (FDA),
• Department of Health and Human Services (DHHS) agencies,
• Governmental agencies in other countries,
• Governmental agencies to whom certain diseases (reportable diseases) must be reported
• Central IRB

Why will this information be used and/or given to others?

• to do the research,
• to study the results, and
• to see if the research was done right.

The investigator is responsible for the preparation (review and signature) and/or retention of the records below. The following records are subject to inspection and must be retained for a period of two years after the date on which the study is terminated or completed.