"Swing" Test May Identify Those At Highest Risk Of Death From Congestive Heart Failure

October 12, 1998

DALLAS, Oct. 13 -- A new test that measures swings in heart rate during the day may help identify individuals with congestive heart failure who are at the highest risk of dying from the condition within a year, according to a study in today's Circulation: Journal of the American Heart Association. Congestive heart failure (CHF) occurs when the heart muscle becomes unable to pump enough blood to meet the needs of the body's other organs. The test measures heart rate variability (HRV), the amount by which the heart rate changes from slow rates to fast rates in one 24-hour period. "The less the heart rate varies over 24 hours, the more likely a person will die of congestive heart failure," says the study's lead author James Nolan, M.D., consultant cardiologist at the Cardiology Center, North Staffordshire Hospital in Staffordshire, England.

In the study, people with the lowest HRV whose fastest heart rate was not much different from their slowest heart rate were three times more likely to die than individuals with the highest HRV. The annual death rate of people with the lowest HRV was 51.4 percent compared to 5.5 percent for those with the highest HRV. People whose HRV was between the two extremes had an annual death rate of 12.7 percent. The test can offer physicians a warning when people are at risk for early death and need intense treatment to save their lives, he says. "The take-home message to doctors is to measure the HRV in their patients with congestive heart failure. If it's high, the person is going to do well. If it's low, he or she is quite likely to die soon and the doctor should adjust treatment to try to prevent that," says Nolan.

"The HRV test will allow physicians to target extra treatment to the 40 percent of patients most likely to benefit. The money saved by not treating low-risk patients can then be allocated to other areas of health care," he says. The report is a follow-up investigation to previous studies indicating that a low HRV soon after a heart attack reduces a person's chance of survival. "There were reasons to think that if HRV is predictive following a heart attack, it might be even more valuable for heart failure patients," Nolan says.

For the study, the scientists selected 433 people in the United Kingdom Heart Failure Evaluation and Assessment of Risk Trial (UK-HEART) with symptoms of severe heart disease. The participants' average age was 62. Heart electrical activity was recorded by a small portable electrocardiograph (ECG) worn by each participant for a full day. Participants were able to continue with their normal daily activities throughout the recording period. The taped ECGs were run through an automatic analyzer that excluded abnormal beats and determined the variability in the 24-hour recording period. Participants were followed for an average of 482 days after their monitoring. Fifty-four deaths occurred during this time, with a total death rate of 9.5 percent.

The HRV is a good way to identify patients who are more likely to die of congestive heart failure. It can be used in conjunction with other measurements such as chest x-ray, blood tests or heart ultrasound examinations, says Nolan. Low HRV may be due to a defect in the autonomic nervous system -- the part of the nervous system that regulates "involuntary" body functions such as breathing and the beating of the heart, says Nolan. "The autonomic nervous system is constantly adjusting the rate at which the heart beats. Those people with the sickest hearts can't do that, so they have very little variability in their heart rate," says Nolan.

"If part of your heart is damaged and functioning inadequately, quality of life is maintained at the expense of overworking the surviving parts of your heart. There are no 'down' times where the heartbeat can slow down, allowing the heart to rest," he says. "And that may lead to a downward spiral of declining heart function and death from congestive heart failure. "Drugs like beta blockers, digoxin, and scopolamine -- a drug used to treat travel sickness that affects the autonomic nervous system -- and simple things like exercise training improve heart rate variability," Nolan says. "These beneficial effects may prevent heart function from deteriorating and keep individuals alive for longer."

Nolan and his colleagues have planned more studies to test the effectiveness of various treatments in prolonging the lives of people with congestive heart failure with low HRV. CHF, which is increasing dramatically in the U.S. population, can be caused by conditions including, but not limited to, high blood pressure, scar tissue from prior heart attacks and coronary heart disease that narrows the vessels that supply blood to the heart muscle. About 4.9 million Americans have CHF. Co-authors are Phillip Batin, M.D.; Steven Lindsay, M.R.C.P.; Richard Andrews, M.R.C.P.; Paul Brooksby, M.D.; Michael Mullen, M.R.C.P.; Wazir Baig, M.D.; Andrew Flapan, M.D.; Alan Cowley, F.R.C.P.; Robin Prescott, Ph.D.; James Neilson, Ph.D.; and Keith Fox, F.R.C.P.

Media Advisory: Dr. Nolan can be reached by phone at 011-44-178-271-5444; or by fax at 011-44-178-271-3071. (Please do not publish numbers.)
-end-


American Heart Association

Related Heart Attack Articles from Brightsurf:

Top Science Tip Sheet on heart failure, heart muscle cells, heart attack and atrial fibrillation results
Newly discovered pathway may have potential for treating heart failure - New research model helps predict heart muscle cells' impact on heart function after injury - New mass spectrometry approach generates libraries of glycans in human heart tissue - Understanding heart damage after heart attack and treatment may provide clues for prevention - Understanding atrial fibrillation's effects on heart cells may help find treatments - New research may lead to therapy for heart failure caused by ICI cancer medication

Molecular imaging identifies link between heart and kidney inflammation after heart attack
Whole body positron emission tomography (PET) has, for the first time, illustrated the existence of inter-organ communication between the heart and kidneys via the immune system following acute myocardial infarction.

Muscle protein abundant in the heart plays key role in blood clotting during heart attack
A prevalent heart protein known as cardiac myosin, which is released into the body when a person suffers a heart attack, can cause blood to thicken or clot--worsening damage to heart tissue, a new study shows.

New target identified for repairing the heart after heart attack
An immune cell is shown for the first time to be involved in creating the scar that repairs the heart after damage.

Heart cells respond to heart attack and increase the chance of survival
The heart of humans and mice does not completely recover after a heart attack.

A simple method to improve heart-attack repair using stem cell-derived heart muscle cells
The heart cannot regenerate muscle after a heart attack, and this can lead to lethal heart failure.

Mount Sinai discovers placental stem cells that can regenerate heart after heart attack
Study identifies new stem cell type that can significantly improve cardiac function.

Fixing a broken heart: Exploring new ways to heal damage after a heart attack
The days immediately following a heart attack are critical for survivors' longevity and long-term healing of tissue.

Heart patch could limit muscle damage in heart attack aftermath
Guided by computer simulations, an international team of researchers has developed an adhesive patch that can provide support for damaged heart tissue, potentially reducing the stretching of heart muscle that's common after a heart attack.

How the heart sends an SOS signal to bone marrow cells after a heart attack
Exosomes are key to the SOS signal that the heart muscle sends out after a heart attack.

Read More: Heart Attack News and Heart Attack Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.