Study finds new possible risk factor of heart disease

Feb 15, 2011

Abnormal heart rate turbulence is associated with an increased risk of heart disease death in otherwise low-risk older individuals, according to a study funded by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health.

This study appears in the Feb. 15 edition of the Journal of Cardiovascular Electrophysiology.

Among the nearly 1,300 study participants, heart rate turbulence, which reflects how well the heart reacts to occasional premature contractions, was an even stronger heart disease risk factor than elevated levels of C-reactive protein. CRP is a potential heart disease biomarker that has emerged in recent years.

Study participants considered at low risk of heart disease based on traditional risk factors were on average 8 to 9 times more likely to die of heart disease during the roughly 14-year follow-up period if they had abnormal heart rate turbulence values. Traditional risk factors include age, gender, , , obesity, diabetes, and smoking. Low-risk individuals with elevated CRP in their blood were about 2.5 times more likely to die than those with normal or low CRP.

"These findings suggest that apparently healthy people might be at increased risk of death from cardiovascular disease, and heart rate turbulence may help us identify them," said Susan B. Shurin, M.D., acting director of the NHLBI. "It will be important to see if we can replicate this finding in other populations."

This study followed 1,272 adults aged 65 and older as part of the NHLBI's Cardiovascular Health Study. Participants were categorized as healthy (no sign of heart disease risk except possibly diabetes), subclinical (some signs of heart disease) or clinical (had a , such as a heart attack). At the onset, participants underwent 24-hour monitoring of their hearts' electrical activity through a small electrocardiographic, or ECG, device called a Holter monitor attached to their skin.

Abnormal heart rate turbulence and CRP levels both appeared to independently correlate with an increased likelihood of dying of heart disease in the group that was categorized as healthy, even after controlling for other risk factors. Abnormal heart rate turbulence–present in about 7 percent of the study participants–also predicted an increased likelihood of heart disease death in the subclinical and clinical groups, though these results were not as pronounced.

Heart rate turbulence refers to how smoothly the heart rate returns to normal after a premature ventricular contraction, a fairly common event in which the second portion of a heart beat is triggered too soon. Due to the improper timing between the atrial and ventricular contractions, the ventricles haven't fully filled with blood and therefore do not push out enough blood to the body. The brain detects this sub-optimal release of blood and instantly increases the heart rate to pump more blood. However, this overcompensation raises blood pressure, causing the brain to react again and lower the heart rate until blood pressure returns to normal.

By analyzing the heart's electrical signals, physicians can measure the magnitude of the initial heart rate jump (turbulence onset) and the speed at which heart rate returns to normal (turbulence slope), and then determine if the heart rate turbulence response is normal or abnormal.

"A heart rate turbulence measurement is insightful because it offers a sign of how well the autonomic, or subconscious, nervous system is functioning," said study author Phyllis K. Stein, Ph.D., a research associate professor of medicine and director of the Heart Rate Variability Laboratory at Washington University School of Medicine in St. Louis. "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 arrhythmias."

Researchers don't yet know if abnormal heart rate turbulence can be treated or prevented. In the meantime, said Stein, interest might grow within the medical community in measuring heart rate turbulence in clinical practice. Currently, this type of measurement is not widely available.

"This study shows a great potential value for heart rate turbulence in diagnostic settings," said Robin Boineau, M.D., a medical officer in the NHLBI's Division of Cardiovascular Sciences. "It appears that signs of heart rate turbulence are also generally present a year or more before clinical manifestations of , indicating that this may be an opportunity for disease prevention in addition to disease prediction."

Explore further: Oil-swishing craze: Snake oil or all-purpose remedy?

add to favorites email to friend print save as pdf

Related Stories

'Healthy' patients at high risk of cardiac death identified

Feb 14, 2011

(PhysOrg.com) -- 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 ...

Resting heart rate can predict heart attacks in women

Feb 04, 2009

A simple measurement of resting pulse predicts coronary events in women independently of physical activity and common risk factors, such as smoking and alcohol consumption, finds a study published on bmj.com today.

Heart beat may provide clues to kidney health

Jul 08, 2010

Individuals with a high resting heart rate and a low beat-to-beat heart rate variability have an increased risk of developing kidney disease, according to a study appearing in an upcoming issue of the Journal of the American So ...

Recommended for you

Suddenly health insurance is not for sale

Apr 18, 2014

(HealthDay)— Darlene Tucker, an independent insurance broker in Scotts Hill, Tenn., says health insurers in her area aren't selling policies year-round anymore.

Study: Half of jailed NYC youths have brain injury (Update)

Apr 18, 2014

About half of all 16- to 18-year-olds coming into New York City's jails say they had a traumatic brain injury before being incarcerated, most caused by assaults, according to a new study that's the latest in a growing body ...

Autonomy and relationships among 'good life' goals

Apr 18, 2014

Young adults with Down syndrome have a strong desire to be self-sufficient by living independently and having a job, according to a study into the meaning of wellbeing among young people affected by the disorder.

User comments : 0

More news stories

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Study says we're over the hill at 24

(Medical Xpress)—It's a hard pill to swallow, but if you're over 24 years of age you've already reached your peak in terms of your cognitive motor performance, according to a new Simon Fraser University study.

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.