Specialized Signals Inside ICDs Provide Ongoing Monitoring for High-Risk Patients
May 6, 2011 – New data presented at the Society for Cardiovascular Angiography and Interventions (SCAI) Scientific Sessions are the first to look at the use of highly specialized signals within implantable cardioverter defibrillators (ICDs) to detect restricted blood flow to the heart in high-risk cardiovascular disease patients outside the hospital setting. Preliminary results from the ST-DETECT trial using high-fidelity intracardiac electrogram (EGM) signals in ICDs show a low spontaneous coronary event rate (such as heart attack) among these patients.
Using EGM signals to monitor and detect changes in the function of the heart has been studied in recent years, but these data are the first to examine the system specifically in patients with ICDs. ICDs are used in patients at risk for recurrent, sustained ventricular tachycardia or fibrillation, when the heart beats too quickly at a rate of more than 100 beats per minute. When an ICD detects ventricular tachycardia or fibrillation, it provides a painless shock to the heart to restore the normal rhythm and can potentially save the patient's life. The addition of the EGM signaling system has the potential to alert healthcare providers and the patients themselves if the patient is undergoing, or is about to undergo, a heart attack, allowing the patient optimal time to seek prompt treatment.
In the study, patients from 27 participating centers were monitored for 24 months following implantation of ICDs containing software for EGM. Patients qualified as high-risk for a spontaneous coronary event (such as heart attack) by having one or more of the following risk factors:
• A recent heart attack (six months or less)
• A recent PCI (angioplasty) or stent
• Multi-vessel disease, with one vessel more than 60 percent blocked, and/or
• A recent positive stress test indicating heart disease
Additionally, the majority of patients were taking multiple medications, including antiplatelets (93 percent), cholesterol-lowering drugs (88 percent), blood pressure-lowering drugs (84 percent) and beta-blockers (93 percent).
Study results show a total of 182 adverse cardiovascular events in 89 of a total of 173 patients. A blinded, external endpoint committee reviewed the ischemia-related events, with the correlation between ischemia-related (blood flow to the heart) events and episodes of ST-segment deviations to be presented. The study was stopped early due to the low rate of heart attack among study participants.
"What's interesting about these data is there were virtually no heart events in this group of very sick patients, suggesting their disease was well managed by a combination of medical therapy and revascularization," said Timothy D. Henry, M.D., FSCAI, director of research and an interventional cardiologist at the Minneapolis Heart Institute at Abbott Northwestern Hospital. "Further research is needed to analyze the use of this signaling system within ICDs, as this innovation could open a new window to detecting heart attacks and preventing heart damage and death."
The ST-DETECT Trial was sponsored by Medtronic.
For more information: www.scai.org