The way the heart responds to an early beat is predictive of cardiac death, especially for people with no conventional markers of cardiovascular disease, according to new research from Washington University School of Medicine in St. Louis.
The conventional risk factors, such as high cholesterol, smoking, diabetes and high blood pressure, account for many but not all deaths from cardiovascular causes. As a result, doctors are always searching for better ways to identify patients at risk of cardiac death.
The new research indicates that an abnormal response to an early beat in the left ventricle, the heart's main pumping chamber, can identify high-risk patients even when they have no other evidence of cardiovascular disease.
"These are people we do not expect to die of cardiac causes," says Phyllis K. Stein, PhD, research associate professor of medicine and director of the Heart Rate Variability Laboratory at the School of Medicine. "They appear healthy, but they're not. We have shown a way they're not healthy that isn't showing up using standard tests."
The work appears Feb. 15 in the Journal of Cardiovascular Electrophysiology.
A ventricular premature beat (VPB) occurs when the ventricle gets an inappropriate signal causing it to beat before it should. VPBs are common, even in healthy people. The question is not whether VPBs occur, but how the body responds to them. The heart's response to a VPB is called heart rate turbulence. It can be measured with a Holter monitor, a device worn for 24 hours that records a person's electrocardiogram, the electrical signals produced by the heart.
When the ventricle beats early, the heart has not finished filling and it pumps less blood to the body than it should. To compensate, the heart rate speeds up to increase blood flow.
But an early beat also empties the heart early, leaving extra filling time afterward. So on the second beat after the VPB, the heart
|Contact: Julia Evangelou Strait|
Washington University School of Medicine