Implanted devices detect high-risk heart failure patients

March 07, 2005

DURHAM, N.C. - Implanted devices intended to optimize the cardiac function of patients with heart failure have provided new insights into which patients might be at higher risk of dying suddenly from their disease, according to researchers at Duke University Medical Center.

Besides maintaining optimal electrical stimulation to the heart, these CRT-D (cardiac resynchronization therapy with defibrillation) devices are giving cardiologists a new view of subtle changes in a key measurement of heart health -- heart rate variability. Patients with little variability -- whose hearts are unable to appropriately react to external stimuli by regulating their beating action -- are known to be at higher risk of suffering a heart attack. The new insight from CRT-D devices is possible because they record detailed data on heart function 24 hours a day.

These new findings are important for two reasons, the researchers said. First, the collected information appears to more accurately identify high risk patients who would benefit from early and aggressive therapy. Secondly, the devices provide cardiologists with objective information about the health status of their patients, information that can be frustratingly difficult to obtain in a typical clinical setting in this medically diverse group of patients, the researchers said.

The results of the study were presented by Duke cardiologist Roosevelt Gilliam, M.D., March 7, 2005, at the annual scientific session of the American College of Cardiology in Orlando. "When you talk to heart failure patients, many times their perceptions of how they feel do not match with their actual clinical status, which can make it difficult for cardiologists to get a true idea of how the disease is progressing," said Gilliam, chief of electrophsysiology at Duke. "This study shows that changes in heart rate variability just might be better in picking out those people at highest risk."

In their analysis of 1,411 heart failure patients who received the CRT-D device, the researchers found a strong correlation between the heart rate variability changes within two weeks of implantation and mortality one year later.

"This approach may play a significant role in targeting a subset of heart failure patients for whom we need to be more aggressive if we don't see early improvement in heart rate variability," Gilliam said. "We would expect that as their heart function improves after implantation, their heart rate variability would improve as well."

Heart failure is a condition marked by the inability of the heart muscles to pump enough oxygen and nutrients in the blood to the body's tissues. Also known as congestive heart failure, its many causes include infections of the heart, coronary artery disease, high blood pressure, previous heart attacks and valve problems. An estimated 4.7 million Americans suffer from the condition, with 400,000 new cases reported each year. Roughly one-half of patients die within five years of diagnosis.

Although there is no cure, drugs can improve the strength of the heartbeat (digoxin), relax blood vessels (ACE inhibitors)or remove the excess buildup of fluid in the lungs (diuretics). Implantable devices are the latest options in preventing arrhythmias that can lead to sudden death, with CRT-Ds being the latest technology.

CRT-Ds perform two main functions. First, the devices electrically stimulate both sides of the heart in coordinated fashion, which optimizes the contractability of already weakened heart muscle. Second, the defibrillator "shocks" the heart back into normal rhythm whenever the heart beats irregularly.

In addition to maintaining the heart, the devices also collect heartbeat-by-heartbeat data that can be downloaded from the device and entered into a computer. One use of the data in this trial was to create a "footprint," or visual representation, of a patient's heart rate variability over time. Patients with a footprint of 30 percent or less in heart rate variability were almost two-and-half times more likely to die after one year.

"A person with normal heart rate variable would have a very wide footprint, while those with sick hearts would have a narrow footprint that represents the reduced variance in heart rate response," Gilliam explained. "These footprints provide us with an unbiased - distinct from the patient's perception - look at how the patient is truly doing. It is an objective finding that you can look at and easily understand."

Gilliam pointed out that the cardiologists are "in uncharted waters" when it comes to the new devices, their role in the treatment of heart failure, and how to make best use of the new data which they can provide. Additional trials will be needed to tease out the relationships between different patient characteristics, the use of the new technology, and patient outcomes, Gilliam said.
-end-
The CRT-D devices were developed by Guidant Corp., Indianapolis, which funds the Heart Failure-Heart Rate Variability Registry, an ongoing national study. Gilliam has no financial ties to Guidant.

Duke University Medical Center

Related Heart Failure 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

Machining the heart: New predictor for helping to beat chronic heart failure
Researchers from Kanazawa University have used machine learning to predict which classes of chronic heart failure patients are most likely to experience heart failure death, and which are most likely to develop an arrhythmic death or sudden cardiac death.

Heart attacks, heart failure, stroke: COVID-19's dangerous cardiovascular complications
A new guide from emergency medicine doctors details the potentially deadly cardiovascular complications COVID-19 can cause.

Autoimmunity-associated heart dilation tied to heart-failure risk in type 1 diabetes
In people with type 1 diabetes without known cardiovascular disease, the presence of autoantibodies against heart muscle proteins was associated with cardiac magnetic resonance (CMR) imaging evidence of increased volume of the left ventricle (the heart's main pumping chamber), increased muscle mass, and reduced pumping function (ejection fraction), features that are associated with higher risk of failure in the general population

Transcendental Meditation prevents abnormal enlargement of the heart, reduces chronic heart failure
A randomized controlled study recently published in the Hypertension issue of Ethnicity & Disease found the Transcendental Meditation (TM) technique helps prevent abnormal enlargement of the heart compared to health education (HE) controls.

Beta blocker use identified as hospitalization risk factor in 'stiff heart' heart failure
A new study links the use of beta-blockers to heart failure hospitalizations among those with the common 'stiff heart' heart failure subtype.

Type 2 diabetes may affect heart structure and increase complications and death among heart failure patients of Asian ethnicity
The combination of heart failure and Type 2 diabetes can lead to structural changes in the heart, poorer quality of life and increased risk of death, according to a multi-country study in Asia.

Preventive drug therapy may increase right-sided heart failure risk in patients who receive heart devices
Patients treated preemptively with drugs to reduce the risk of right-sided heart failure after heart device implantation may experience the opposite effect and develop heart failure and post-operative bleeding more often than patients not receiving the drugs.

How the enzyme lipoxygenase drives heart failure after heart attacks
Heart failure after a heart attack is a global epidemic leading to heart failure pathology.

Novel heart pump shows superior outcomes in advanced heart failure
Severely ill patients with advanced heart failure who received a novel heart pump -- the HeartMate 3 left ventricular assist device (LVAD) -- suffered significantly fewer strokes, pump-related blood clots and bleeding episodes after two years, compared with similar patients who received an older, more established pump, according to research presented at the American College of Cardiology's 68th Annual Scientific Session.

Read More: Heart Failure News and Heart Failure 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.