There are over 1 × 101 acute myocardial infarctions (AMI) each year in the U.S. with more than 400,000 of these resulting in death. Early identification of AMI and prompt treatment has been shown to significantly improve clinical outcomes. Experimental and clinical studies have shown that most of the irreversible damage to the myocardium occurs during the first 2 hr after coronary occlusion. Therefore, the early arrival at the hospital for a reliable diagnosis and initiation of treatment is paramount to improve the outcomes of myocardial infarction. However, despite efforts at educating the public over the past decade, the mean time from AMI symptom onset to arrival at a hospital for treatment has remained, disappointingly, at 2.5 to 3.0 hr. The largest proportion of the total prehospital delay is the interval between the onset of symptoms and the decision to seek medical treatment. If patients would take action during the first hour following symptom onset, many lives and significant cost could be saved.A potentially ideal solution is therefore to implant a device that monitors the electrical activity of the patient's heart and is capable of accurately detecting ST changes that result from occlusions in any of the three coronary arteries and also heart rate abnormalities. Such a device could then autonomously alert the patient to seek the appropriate level of medical attention. For coronary occlusions, a high priority “Emergency” alarm would induce the patient to immediately call 911 for a potential heart attack. For other, nonlife threatening events, a lower priority “See Doctor” alert would be appropriate, resulting in scheduling an appointment to have a clinician review of the event recordings.Angel Medical Systems has developed the QGUARD system. The purpose of the QGUARD system is to provide a means of detecting rapidly progressive ST shifts and other cardiac irregularities, capture the related electrogram data, and alert the subject to seek medical attention (as programmed by the subject's physician) when an alarm threshold has been exceeded. The QGUARD is designed to detect acute changes in the ST segment that are statistically abnormal relative to the patient's self-normative ST segment. Patient alerting should help decrease the time to presentation by warning the patient to seek medical attention immediately. Recording of heart rate anomalies (e.g., high, low, or irregular heart rates) with or without patient alerting can collect important cardiac data allowing the patient's doctor to identify and diagnose various cardiac arrhythmias such as bradycardia, tachycardia, and atrial fibrillation.The QGUARD system is currently under development. It is aimed at a patient population consisting of people who have survived a first heart attack as well as those at a high risk of having a heart attack (i.e., because of family history, high cholesterol, etc.).The individual components of the QGUARD system include:The QGUARD system has two levels of patient alerting signals:The EMERGENCY alarm and SEE DOCTOR alert signals have very different vibration and beeping patterns to make it easy for the patient to differentiate one type of alerting signal from the other and act accordingly. The QGUARD programmer provides the physician with the ability to map each detectible event to an Emergency alarm, a See Doctor event, or to instruct the IMD to save data associated with an event detection for later review (without alerting the patient) or to ignore the detected event altogether.The QGUARD IMD and QGUARD lead both use proven biocompatible materials currently used in many approved pacemakers, implantable cardiac defibrillator and intracardiac leads.An early human study involving testing the response of the algorithm to total coronary occlusions during coronary percutaneous coronary intervention (PCI) procedures showed the potential for excellent sensitivity. A sample is shown in Fig. 4.Figure 4 shows a sample recording of cardiac signals from the two QGUARD vectors (the “up” vector (upper trace) and the “down” vector (lower trace), taken during balloon inflation during the PCI procedure.The orange horizontal bars are algorithm determined threshold limits for each beat for what is considered a large ST change for this patient. The blue dots are algorithm determined PQ and ST values for each beat. For this particular patient, the algorithm detected an ST shift large enough to exceed the threshold in the up vector (and not in the down vector.The overall results for this early human study are summarized in Table 1.The significant design achievement of the QGUARD is the development of a reliable ST shift detection algorithm that can function in the presence of axial shifts of the heart and muscle and other body electrical noise that had previously made such monitoring difficult. This algorithm uses a patented exponential averaging technique with the ability to ignore periods of noise.