Heart Disease Risk Factor Found in Healthy People
Researchers believe they have discovered a new risk factor which explains why seemly healthy people die from undetected heart disease.
The results of the study, funded by the National Institute of Health, showed that the participants who did not have traditional heart disease risk factors but had abnormal heart rate turbulence were 9 times more likely to die from cardiac death.
Known risk factors such as obesity, smoking, high cholesterol, high blood pressure, and diabetes account for most heart disease deaths. However, there are still many people that die who have had normal cardiac exams and do not have any of the expected risk factors.
Study author Phyllis K. Stein, PhD stated, “They're actually not healthy. Something is wrong. But the conventional risk factors don't pick it up.”
Until now, doctors and researchers have searched for answers to why this occurs but have fallen short of finding a reliable predictor.
Researchers at the Washington University School of Medicine in St. Louis reported that the way that the heart responds to a common cardiac event, called a premature ventricular contraction (PVC), is highly predictive of death from heart disease.
A PVC occurs when one chamber of the heart beats too early. The result is less blood being pumped throughout the body. The heart reacts by speeding up and then slowing down to normalize blood flow before resuming its normal beats. This compensation mechanism is called heart rate turbulence.
The study found that of the 1,300 healthy adult participants those who had abnormal heart rate turbulence were 9 times more likely to die from cardiac disease within a 14 year period than those who did not. Furthermore, the researchers found that this predictor was much stronger than C-reactive protein, a common heat disease marker used in clinical settings today.
“A heart rate turbulence measurement is insightful because it offers a sign of how well the [subconscious] nervous system is functioning” said Stein. “If someone's heart doesn't react well to these uncoordinated beats that might mean it's not good at reacting to other issues like sudden stress or severe arrhythmia”.
PVCs occur in up to 1 in 5 people and are generally considered to be harmless. Therefore, the concern is not that a person is having PVCs, but how their body reacts to them.
Heart rate turbulence can be measured by non-invasive test called a Holter. A Holter is a small device which measures a patient's heart activity over the course of 24 hours. However, at this time there is only one type of Holter device which can measure heart rate turbulence and this has not yet been made widely available.
Stein hopes that this research will lead to applying heart rate turbulence monitoring in a clinical setting for more accurate and earlier detection of heart disease.