Clinical and Industry News

Permanent Intracardiac ST Segment Monitoring Undergoing Evaluation of Safety and Effectiveness in Two Trials

C. Michael Gibson, MS, MD, Beth Israel Deaconess Medical Center, is serving as lead investigator on two large-scale studies of ST segment monitoring. The St. Jude Medical Analyze ST Study is designed to investigate the safety and effectiveness of ST segment monitoring as an additional feature of the company’s implantable cardioverter defibrillators (ICDs). Similarly, the Angel Medical Systems ALERTS Study is designed to investigate the potential benefits of continuous ST segment monitoring and alerting in advanced coronary artery disease (CAD) patients who are not indicated for an ICD. The AngelMed study uses the Guardian^™ implantable heart monitor. Angel Medical Systems and St. Jude Medical collaborated on the unique monitoring algorithms used in both devices. 

“These two clinical studies assess both the safety and effectiveness of ST segment monitoring using implantable device technology and may prove it to be effective in early detection and warning of potentially life-threatening ischemia,” said Dr. Gibson. “This would allow us to shift the paradigm for treatment closer to the onset of the cause of the heart attack and could improve clinical outcomes.”

Dr. Gibson also presented a poster entitled “Size and duration of ischemic events detected using permanent intracardiac ST segment monitoring: First five years of human experience” at the March 2012 American College of Cardiology Scientific Sessions.

“We know that ST segment changes can help us to identify CAD events, and that patients with ICDs often also have CAD, so the continuous, internal ST segment monitoring that is possible with this technology could provide physicians of those patients with an early warning signal when a patient is experiencing an ischemic event,” said Dr. Mark Carlson, Chief Medical Officer and Senior Vice President of Research and Clinical Affairs for the St. Jude Medical Cardiac Rhythm Management Division. The studies are occurring at multiple centers throughout the country, with some centers participating in both studies simultaneously.

Half of patients experiencing a heart attack have no symptoms (silent MI) or atypical symptoms that cause confusion or delay about seeking care. Even including patients with symptoms, average pre-hospital delay is over 3 hours because patients wait to call 911. This delay helps result in more than half of MI deaths occurring before reaching a hospital. The AMA indicates that 18% of men and 35% of women experience a second MI within six years of having a recognized first attack. CAD needs to be managed on an ongoing basis to avoid reoccurring, life-threatening acute coronary events. Furthermore, approximately two-thirds of ICD patients have cardiac ischemia, with many more having risk factors for developing cardiovascular disease.

The AngelMed Guardian System heart monitor is designed to track significant changes in the heart’s electrical signal from a standard pacemaker lead, identify the signature of acute thrombotic occlusions when they occur, and then alert the patient directly to seek medical attention. The device is being studied in high-risk heart patients who do not qualify for an ICD, but who have had a STEMI, NSTEMI or unstable angina in their recent past. “Annually, more than 1.3 million people have a heart attack, yet over 90% do not qualify for an ICD or pacemaker,” says AngelMed’s Chief Medical Officer, Dr. Tim Fischell. “The Guardian has the potential to benefit the very large number of patients with this need.”

The Analyze ST Study is a pivotal IDE investigation of up to 5,228 patients at approximately 200 medical centers. The ALERTS Study is a pivotal IDE investigation of up to 1020 patients in 75 medical centers. To participate in the either study, patients must meet various inclusion criteria. For more information on the AngelMed Guardian System or the ALERTS study protocol, contact David Keenan, Vice President of Clinical and Regulatory Affairs at (732) 542-3350, or visit www.angel-med.com. For information on the St. Jude Medical Analyze ST Study, contact Tamara Shipman, Director of Clinical Affairs at (408) 552-6410.

Biodegradable Stent Safe for Long-Term Treatment of CAD

The first fully biodegradable coronary artery stent implanted in humans proved safe in a 10-year study published in Circulation, an American Heart Association journal.

The biodegradable Igaki-Tamai stent is used in nine European Union countries and Turkey — but not in the United States — to treat peripheral artery disease. However, no countries have approved the Igaki-Tamai stent for treating clogged heart arteries.

“We have needed this long-term clinical data to clarify the coronary safety of the stent,” said Kunihiko Kosuga, MD, PhD, co-author of the study and director of cardiology at Shiga Medical Center for Adults in Moriyama City, Japan. “Our findings will pave the way for the entry of coronary stents made of biodegradable polymers into the real world of interventional cardiology.”

This biodegradable stent is made of poly-l-lactic acid, a cornstarch-based material, which dissolves into the artery wall. 

In the study, researchers tracked 50 Japanese patients (44 men, average age 61 years old) who received 84 Igaki-Tamai stents between September 1998 and April 2000. The stents weren’t coated with drugs. After an average 10 years, researchers found:

• The survival rate was 98 percent free from cardiac death and 87 percent free from death from all causes.
• Fifty percent of patients experienced no major cardiac complication.
• Acceptable major event complication rates were similar to those for bare metal stents.

Although researchers expected stent degradation to take six months, the study indicated the stent was totally absorbed in three years.

“Fully biodegradable stents may hold an important position as the next generation of coronary devices,” Kosuga said.

Older Adults With ECG Abnormalities May Be At Increased Risk of Coronary Heart Disease Events

In a study that included elderly men and women without preexisting cardiovascular disease, major and minor electrocardiographic abnormalities were associated with an increased risk of coronary heart disease events and improved the prediction of coronary heart disease events such as heart attack, beyond traditional cardiovascular risk factors, according to a study in the April 11 issue of JAMA.

“In populations of older adults, prediction of coronary heart disease through traditional risk factors is less accurate than among middle-aged adults,” according to background information in the article. Electrocardiographic (ECG) abnormalities are common in older adults. “However, performing routine ECG among asymptomatic adults is not supported by current evidence. Considering the higher prevalence of both cardiovascular disease and ECG abnormalities in older adults, risk prediction incorporating ECG might be more useful in this group. To date, few studies have examined the improvement of cardiovascular disease risk prediction using ECG abnormalities in a population of older adults and none could adequately adjust the analyses for presence of previous cardiovascular disease and traditional cardiovascular risk factors.”

Reto Auer, MD, of the University of Lausanne, Switzerland, and University of California, San Francisco, and colleagues conducted a study to determine whether baseline major and minor ECG abnormalities, development of new ECG abnormalities, and persistent ECG abnormalities during follow-up were associated with new coronary heart disease events, independent of traditional cardiovascular risk factors. The population-based study included 2,192 white and black older adults ages 70 to 79 years without known cardiovascular disease. Adjudicated coronary heart disease events were collected over 8 years, between 1997-1998 and 2006-2007. Baseline and 4-year ECG abnormalities were classified as either major or minor. The addition of ECG abnormalities to traditional risk factors were examined to predict coronary heart disease events.

Of the 2,192 participants in the study, 506 (23%) had major and 276 (13%) had minor ECG abnormalities. During a median follow-up of 8.2 years, 351 participants had coronary heart disease events and 602 died (96 deaths from coronary heart disease). Analysis of data indicated that major and minor ECG abnormalities at baseline were both associated with an increased risk of coronary heart disease. After adjustment for various cardiovascular risk factors, compared to participants without ECG abnormalities, participants with minor ECG abnormalities at baseline had a 35% increased risk for coronary heart disease events, and participants with major ECG abnormalities had a 51% increased risk. Stratification of analyses by race showed similar findings between white and black participants.

“The addition of ECG abnormalities to the model adjusted for traditional cardiovascular risk factors resulted in reclassification of 13.6% of intermediate-risk participants and 7.1% in the overall sample. When ECG abnormality was added to the model adjusted for traditional cardiovascular risk factors, 176 intermediate-risk participants (8%) were reclassified as high risk, of whom 27 (15.2%) experienced events. Conversely, 136 participants (6.2%) were reclassified as low risk, of whom 7 (5.2%) experienced events,” the authors write. Including ECG abnormality in the model adjusted for cardiovascular risk factors placed 65% of the overall population into either the highest-risk or lowest-risk categories vs. 49% with traditional risk factors alone.

After 4 years, 208 participants had new and 416 had persistent abnormalities. After adjustment for cardiovascular risk factors, both new and persistent ECG abnormalities at 4 years were associated with an increased risk of subsequent coronary heart disease events.

“In conclusion, we found that major and minor ECG abnormalities are associated with future coronary heart disease events and provide modestly improved risk reclassification beyond traditional risk factors. Risk prediction with traditional risk factors is less accurate in older persons compared with middle-aged adults. Given the safety, the low cost, and the wide availability of ECG, ECG data might be useful to improve coronary heart disease risk prediction in older adults. Whether ECG should be incorporated in routine screening of older adults should be evaluated in randomized, controlled trials,” the researchers write.

In an accompanying editorial, Philip Greenland, MD, of the Northwestern University Feinberg School of Medicine, Chicago, writes that several groups currently advise against the practice of routine screening with resting ECG in asymptomatic patients.

“These include the U.S. Preventive Services Task Force and the American College of Cardiology Foundation/American Heart Association (although some specific higher-risk groups were considered as possible targets of such testing). Even Consumer Reports has recommended against routine ECG testing. For the time being, in the absence of clear evidence of benefit and no clear implications for costs, the best advice is not to perform ECGs in asymptomatic patients, regardless of age. However, a careful and detailed cost-effectiveness analysis would be a useful next step in the translation of the cumulative risk information into an evidence-based practice recommendation.”

Source: JAMA 2012;307[14]: 1497-1505, 1530-1531.