The implantation of a defibrillator can significantly improve survival after a heart attack.
The study, published in JAMA, investigated Medicare patients who experienced heart attacks between 2007 and 2010 and had low ejection fraction, an indicator of how well the heart's left ventricle pumps blood with each beat.
Previous research has associated the use of implantable cardioverter defibrillators (ICDs) with a lower risk of death in the 2 years following implantation.
"Defibrillators are life-saving therapies that have a lot of evidence supporting their use," says senior author Dr. Tracy Wang, an associate professor of cardiology at the Duke University School of Medicine. "But not every older patient wants one. There is a trade-off between the risks and benefits of the device. But current data suggests that we are grossly underutilizing this therapy."
ICDs shock the hearts of patients back to pumping if they experience a sudden cardiac arrest. These arrests can be fatal; according to the study authors, more than 350,000 people experience sudden cardiac death in the US every year. Research suggests that as many as 80% of these patients were eligible for ICDs but did not have one implanted.
Although the benefits of using these devices have been demonstrated in previous studies, most clinical trials have focused on patients in their 60s. As a result, the benefits to defibrillator use in older adults has yet to be established.
For the study, the researchers examined ICD implantation rates and associated mortality rates among 10,318 patients with a median age of 78 who had experienced heart attacks and had ejection fractions of 35% or less. Data were obtained from 441 hospitals across the US, each participating in the National Cardiovascular Data Registry.
They found the cumulative 1-year ICD implantation rate among these patients was 8.1%. Those that received ICDs within a year of their heart attack were more likely to be male, younger than average for the sample group, have larger areas of heart damage and have had previous coronary artery bypass graft surgery than patients that did not receive ICDs.
Patients that received ICDs also had a one third lower risk of death for the 2 years following their heart attacks.
Recommended wait before implanting could influence rates of use
The researchers suggest that the low rates of use could likely be due to the advanced age of some of the participants, transitions between hospital and outpatient care and a mandatory waiting period to get an ICD implanted.
"The optimal timing for implanting a defibrillator is still in question, but current guidelines recommend that patients wait at least 40 days after their heart attack," states lead author Dr. Sean Pokorney, a cardiology fellow at Duke University School of Medicine in Durham, NC.
"If the patient's heart is still having trouble pumping blood after 40 days, they would be eligible. But a lot can happen in that 40 days."
During this 40 day period, patients are typically discharged from hospital and care is transitioned to an outpatient care team. Those that remain in contact with their cardiologist and keep their follow-up appointments are more likely to receive ICDs than patients that do not.
"We believe that age alone should not prevent eligible people from getting devices," Dr. Pokorney says. "We should be trying to understand how to refine patient selection toward those who are most likely to benefit from the device, and close any system-level gaps that present a barrier to optimal defibrillator use."
As the study is a retrospective observational study, further research will be required to inform approaches to ICD use in eligible patients and to reveal how clinicians can improve patient follow-up and communication after heart attacks.
"Even if the ICD implantation rate were twice what Pokorney et al found, it is concerning that so few potentially ICD-eligible elderly patients are undergoing implantation, especially considering that ICDs significantly improve survival," states Dr. Robert G. Hauser, of the Minneapolis Heart Institute, writing in an accompanying editorial.
Recently, Medical News Today reported on new research warning that electromagnetic interference from smartphones can affect the functioning of ICDs.