John Messenger, MD, is the medical director of the Cardiac Care Unit (CCU) at MemorialCare Heart and Vascular Institute. In this interview he describes his use of the AngelMed Guardian® system at Long Beach Memorial Medical Center, as well as his involvement in the ALERTS clinical study. The AngelMed Guardian system, which is currently available for investigational use only in the U.S., is an implantable cardiac monitoring and alerting system designed to warn cardiac patients of potentially life-threatening heart conditions.

Explain how the AngelMed Guardian System works. What are the components of the system?
The AngelMed system uses a device, similar in size to a pacemaker, which is implanted in the left pectoral region of the chest and has a lead with an electrode to the right ventricle. If there are ischemic changes of significance, an algorithm in the AngelMed Guardian system will identify these electrocardiographic ST changes and alert the patient. It is the same as a positive treadmill test or abnormal EKG, but can be identified much earlier in many patients. To notify the patient, the device will give either a “911” signal, which directs the patient to immediately go to the ER or call the paramedics, or a “Call your doctor” signal, which is a different signal pattern that originates with the implanted device and is sent via telemetry to a hand-held telemetry device carried by the patient. In addition, the signal provides an audible as well as vibratory ring under the skin, so if the patient has difficulty hearing, they can still sense the vibration and know when to call a physician. So that is a basic explanation of what happens if a patient has ischemia but no demonstrable sensation of chest pain.

In what patients is this system most beneficial for?
In diabetics, there is a problem associated with not having proper sensing of pain, so when they experience a heart attack, they often present without severe discomfort. Since the population is made up of at least 25 percent of patients with diabetes, they are the more identifiable patients who would benefit from this type of device. For patients with clotting disorders or other problems that tend not to be typical or predictable, this system gives these patients early warning so they can get to their physician before damage to their heart occurs.

Tell us about the ALERTS study at Long Beach Memorial Hospital. In how many cases have you implanted the AngelMed Guardian System?
We’ve been involved in the study for a little over a year. It is a randomized control study, which means that half of the patients receive the full-featured device. The other half, referred to as the control group, receives a fully-functional device as well; however, the patient alerting feature is turned off for the first six months, and after 6 months, the alarm is turned on. In the meantime, we continue monitoring, and if for some reason there are concerns regarding an event that occurs, we monitor the patients very carefully and perform nuclear studies during the time to be certain that we’re not missing something during the control period.