A renowned cardiologist and researcher at the University of Miami Miller School of Medicine, in collaboration with colleagues at Oulu University in Finland, has found evidence of previously undetected heart attacks in about 40 percent of people whose sudden deaths were associated with coronary artery disease. “We need more effective screening tools to identify individuals with heart disease who have a silent risk of sudden death,” said Robert J. Myerburg, M.D., a cardiac electrophysiologist, professor of medicine and physiology, and the American Heart Association Chair in Cardiovascular Research.
While a silent heart attack (myocardial infarction) may have no symptoms, it typically leaves scar tissue on the heart muscle that can be identified through a magnetic resonance imaging (MRI) scan, said Dr. Myerburg. However, it’s not practical to have every adult at potential risk for sudden cardiac death undergo an MRI scan to detect unrecognized heart disease. “Electrocardiography (ECG) screening may be able to identify abnormalities in these at-risk individuals, but further research is needed to find effective ECG and clinical indicators,” he added.
The report, “Association of Silent Myocardial Infarction and Sudden Cardiac Death,” was published recently in the Journal of the American Medical Association Cardiology (JAMA Cardiology). The collaborative study was done with researchers from the University of Oulu in Finland, and senior author M. Juhani Junttila, M.D., spent a year doing research at the Miller School before returning to the faculty at the University of Oulu. He had previously been a visiting Miller School researcher about eight years ago.
The study was designed to determine the prevalence of silent myocardial infarction (SMI) in individuals who experienced sudden cardiac death without a prior diagnosis of coronary artery disease and to detect ECG abnormalities in these people.
The researchers examined the Finnish Genetic Study of Arrhythmic Events (Fingesture), a unique database consisting of 5,869 individuals who experienced sudden cardiac death in northern Finland between 1998 and 2017. All cases were verified by an autopsy in accordance with Finnish law concerning unexpected deaths.
In this case-control study, 3,122 individuals did not have prior knowledge of coronary artery disease, and 42.4 percent of that group had scarring associated with silent myocardial infarction at autopsy. Of those with electrocardiograms recorded prior to death, 67 percent had abnormal findings.
The study found that individuals with silent myocardial infarction tended to be older, have a higher heart weight, and be more likely to die during physical activity than those without prior myocardial infarctions.
“Coronary artery disease is the most common underlying cause of sudden cardiac death throughout the world,” said Dr. Myerburg. “If we can identify high-risk individuals with prior silent heart attacks, we may be able to do a better job in predicting and preventing those deaths and disabilities among survivors of cardiac arrest.”