A common test that records the heart's electrical activity could predict potentially serious cardiovascular illness, according to a UC San Francisco-led study.
A cardiac condition called left anterior fascicular block (LAFB), in which scarring occurs in a section of the left ventricle, may not be as benign as currently thought and could increase the likelihood of heart failure, sudden cardiac death or atrial fibrillation.
In a study to be published on April 17 in the Journal of the American Medical Association (JAMA), UCSF researchers and their colleagues at Wake Forest School of Medicine and the University of Washington, Seattle, analyzed data on 1,664 people over the age of 65 who were medically followed for 16 years.
The researchers selected those who had no evidence of cardiovascular disease from the National Institutes of Health-sponsored Cardiovascular Health Study. People with heart failure, high blood pressure or diabetes, or who had heart attacks, were excluded from the study sample.
"We then compared those with LAFB to those with a normal electrocardiogram (EKG)," said senior author Gregory Marcus, MD, an electrophysiologist with the UCSF Division of Cardiology and an associate professor in residence with the UCSF School of Medicine. "We found that those who had LAFB indeed had a higher risk of atrial fibrillation, congestive heart failure and death."
After adjusting for other potential confounding variables, LAFB posed a 57 percent greater risk for sudden cardiac death, an 89 percent greater risk for atrial fibrillation, and a 143 percent greater risk for heart failure.
LAFB is a blockage of one of the electrical branches that delivers electrical signals to a part of the left ventricle, one of two chambers in the heart. Small studies suggest it is associated with fibrosis or scarring of the left ventricle, but the clinical ramifications of this have not been previously studied. It is unknown how many people LAFD affects.