Using magnetic resonance imaging (MRI) scans of the heart wall, researchers at Johns Hopkins have found that people whose muscle wall thickness contained more than 25 percent scar tissue were approximately nine times more likely to test positive for a fast and dangerous heart rhythm known as ventricular arrhythmia.
Patients at risk of such arrhythmias often have a heart defibrillator implanted, a small device that delivers an electrical shock to restore their cardiac rhythm in case the heart beats too rapidly to pump enough blood to the rest of their body. Statistics from the United States Centers for Disease Control and Prevention estimate that each year more than 400,000 Americans suffer a sudden cardiac death, at least 30 percent of which are due to arrhythmia.
"If further tests confirm that MRI measurements of scar tissue accurately predict the risk of arrhythmia-related sudden death, these could become the gold standard for screening who really needs or does not need a defibrillator," says the study's senior author, electrophysiologist Henry Halperin, M.D., a professor of medicine, radiology and biomedical engineering at The Johns Hopkins University School of Medicine and its Heart Institute. "While tests are widely available to screen patients with coronary artery disease for risk of sudden cardiac death, tests are not so effective for identifying the many who will die suddenly from arrhythmias."
Indeed, while the U.S. National Center for Health Statistics estimates that more than 1 million Americans currently have a defibrillator, national studies published early this year have shown that only 5 percent of these devices ever fire to correct a heartbeat.
The latest Hopkins findings, which appear in today's edition of the journal Circulation, are believed to be the first to search in the heart's architecture - rather than its pumping function and electrical signaling - and so far the only study to analyze this a
Contact: David March
Johns Hopkins Medical Institutions