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Boston, MA— An article, published in Circulation by Laurel K. Leslie, MD, MPH from the Tufts Clinical and Translational Science Institute (CTSI) and colleagues from Tufts Medical Center and Floating Hospital for Children at Tufts Medical Center, has evaluated the lifesaving benefits and costs of screening programs for the prevention of sudden cardiac death (SCD) in children and adolescents. The authors found that screening can save lives, but that because it targets rare conditions and available tests have limited accuracy, screening for SCD is costly, compared to other life-saving measures.

Although rare, SCD often receives widespread attention because it is unexpected and can occur during childhood. Those factors have prompted many parents and policy makers to support screening programs. To help decision makers and the public understand whether more SCD screening is warranted, the authors, including collaborating clinical researchers from Children’s Hospital Boston, compared the potential life saving benefits (measured in terms of life years saved) to program costs. They considered two groups thought to be at elevated risk: school-aged children taking stimulants, which are often used to treat Attention Deficit Hyperactivity Disorder (ADHD), and adolescents playing organized sports. The research team determined that each year of life saved would cost from $90,000 (to screen adolescents before they participate in sports) to $200,000 (to screen children before they take ADHD medications).

Although there is no hard and fast line separating worthwhile and expensive public health interventions, programs can be compared to get an idea of their value. For example, interventions that cost $90,000 to $200,000 per life year saved are considered expensive, compared to other interventions, which often save life years at $50,000 to $100,000, or even less. The results of this study suggest that finite public health resources might be better spent elsewhere.

The “human cost” of screening suggests its true price may be even higher. Because conditions causing SCD are so rare, even an occasional “false positive” means that for every previously undiagnosed child accurately identified, many children who would never have died from SCD may be labeled as being at-risk.

The research team stressed that the cardiac conditions causing SCD in children are incredibly rare. Many are cardiac conditions are genetic and there may be a family history of early (< 50 years of age) or unexplained SCD in a family member. Dr. Leslie advises that “the most concerning family history in a child is when a parent or sibling is diagnosed with a likely familial cardiac disease; those children should certainly be evaluated.” Since some disorders that cause SCD may not be identifiable on an ECG until late adolescence or early adulthood, an ECG in a parent with a positive family history may provide more information than an ECG in a child. Another indication to consult with a doctor is if a child reports any experiences of fainting or shortness of breath with strong emotions or during exertion (not related to a medical condition like asthma).

Newswise  April 11 2012— Can a simple diagnostic test used to measure a heart’s electrical activity help predict heart attacks? And can that knowledge help doctors reroute their patients away from coronary heart disease?

These are the questions researchers at UCSF asked in a comprehensive eight-year study focused on senior citizens in the United States. Researchers found a higher risk of heart attack when abnormalities showed up on electrocardiogram (EKG) results of healthy elderly people.

“We did not include them if they reported a previous heart attack,” said lead author Reto Auer, MD, a research fellow at UCSF’s Department of Epidemiology and Biostatistics. “So we looked at people who lived independently – not in assisted living facilities – with no history of heart attacks or coronary heart disease.”

The findings, scheduled to be published tomorrow in theJournal of the American Medical Association (JAMA), help answer the question of whether or not EKGs can be used to detect heart disease earlier in patients who don’t have chest pain or other symptoms.

“This research is taking the information from an EKG and adding it to other traditional risk factors to better predict who is going to have a heart attack,” said second author Douglas Bauer, MD, director of the UCSF Division of General Internal Medicine Research Program.

FOCUS ON HEALTHY SENIOR CITIZENS

Researchers studied 2,192 healthy adults aged 70 and older for eight years in Memphis, Tenn., and Pittsburgh. Those with EKG abnormalities had more heart attacks. The results were consistent even when researchers took into account known risk factors for heart attacks, such as smoking, high cholesterol, high blood pressure and diabetes.

At baseline, 276 (13%) participants had minor and 506 (23%) major EKG abnormalities. During follow-up, 351 participants (16%) had coronary heart disease (CHD) events (96 heart-related deaths, 101 heart attacks, 154 hospitalizations for chest pain or a procedure to restore blood flow to the heart). Both baseline minor and major EKG abnormalities were associated with an increased risk of heart disease after adjusting for traditional risk factors.

Each abnormality was categorized in terms of the level of experienced risk. High risk markers included left bundle branch block, a cardiac condition in which the left ventricle contracts later than the right ventricle, as well as major ST-T wave changes in an EKG, among others. Low risk markers included subtle ST-T wave changes and T-wave abnormalities.

“There was a trend towards increased coronary heart disease (CHD) risk from no abnormality to minor, and from minor up to major abnormality,” Auer said. “But both minor and major EKG changes were significantly associated with an increased risk of CHD.”

GENDER AND RACIAL VARIATIONS?

Researchers were also interested in whether or not gender or self-reported racial differences played a role in determining a healthy person’s likelihood of a future heart attack among the 2,192 participants who identified themselves as either Caucasian or African American. Researchers found no correlation between elevated risk factors and gender or race.

“It was a good surprise,” Auer said. “It shows that it’s really the EKG changes that predict risk.”

Researchers say it is premature to advocate for the widespread use of their findings in a clinical setting, but that their initial evidence suggests there may be a role for EKG in adding to traditional risk factors, to better predict who is at risk for a heart attack.

“Anytime someone goes into the emergency room, especially elderly people, they typically get an EKG,” Auer said. “So in the patient’s electronic record system, you could include these EKG abnormalities as part of the patient’s overall risk – but we’re not there yet.”

For now, though, researchers recommend patients become familiar with well-established risk factors that health care providers use to counsel individuals for their risk of future heart attacks and other heart problems.

CONTROVERSY SURROUNDING EKGS

Organizations such as the American Academy of Family Physicians recommends against ordering annual EKGs or any other cardiac screening for low-risk patients without symptoms. They say “there is little evidence that detection of coronary artery stenosis in asymptomatic patients at low risk for coronary heart disease improves health outcomes.”

The American Heart Association (AHA), however, recommends that EKG is reasonable for assessing the risk of coronary heart disease events of adults with hypertension or diabetes even though the U.S. Preventive Services Task Force (USPSTF) found that there is insufficient evidence to recommend for or against routine screening in adults at increased risk of heart disease. For adults at low risk, the AHA recommends that it may be considered while the USPSTF recommends against screening. However, prediction of heart attack by major cardiovascular risk factors is not as reliable in elderly adults as in younger individuals.

“Our view is that novel screening interventions should be tested on clinical outcomes,” Auer said. “Just because you know you might be at increased risk does not mean that you will be better off if your treatment is modified as a consequence of the test.”

This finding, still, could help an estimated 785,000 Americans who will have a first heart attack this year, and 470,000 who will have a recurrent attack. Heart disease remains the number one killer in the United States, accounting for one out of every three deaths, according to the American Heart Association.

Auer is the lead author of the paper; Bauer is the second author; co-authors are Pedro Marques-Vidal, MD, PhD, and Jacques Cornuz, MD, MPH, of the University of Lausanne, Switzerland; Javed Butler, MD, MPH, of Emory University School of Medicine; Lauren J. Min, PhD; Suzanne Satterfield, MD, of the University of Tennessee Health Science Center; Anne B. Newman, MD, MPH, of the University of Pittsburgh’s Department of Epidemiology; Eric Vittinghoff, PhD, of the UCSF Department of Epidemiology and Biostatistics; and Nicolas Rodondi, MD, MAS of the University of Lausanne, Switzerland.

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.

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 is extra full and pumps more blood to the body than it should. To compensate properly, the heart rate slows down.

A healthy heart will alternately speed up and slow down to compensate for the over- and under-filling that follows a VPB until the amount of blood filling the heart returns to normal.

Abnormal heart rate turbulence occurs when the heart can’t compensate in this way.

“It’s a clear test of whether the autonomic nervous system, which regulates your heart rate, can adapt to a challenge,” Stein says.

Stein and colleagues analyzed Holter monitor recordings for almost 1,300 patients over age 65 recorded between 1989 and 1993.

The patients were divided into three groups based on an assessment of their cardiovascular health. Those in the “clinical” group had a history of cardiovascular disease such as heart attack or surgery to open narrow blood vessels. Those in the “subclinical” group had traditional risk factors for cardiovascular disease such as high blood pressure or diabetes but had never been treated for cardiovascular disease. And those in the “healthy” group had no evidence of clinical or subclinical disease.

In all three groups, abnormal heart rate turbulence was predictive of cardiac death. But the association was especially strong in the healthy group. Of the 357 patients classified as healthy, 21 had abnormal heart rate turbulence. These 21 people were almost eight times more likely to die of cardiac causes than the rest of the healthy group.

“Even though it’s a small group of people, they’re actually at very high risk,” Stein says.

In fact, over the next 12 years, the people in the healthy group with abnormal heart rate turbulence had worse survival than the people with subclinical disease but good heart rate turbulence.

“They’re actually not healthy,” Stein says. “Something is wrong. But the conventional risk factors don’t pick it up.”

Stein and her colleagues also looked at levels of C-reactive protein, a measure of inflammation associated with cardiovascular disease. While C-reactive protein predicted cardiac death in the healthy group, it had no impact in the subclinical and clinical groups. Since heart rate turbulence was predictive in all three groups, it may prove better than C-reactive protein in predicting risk of cardiovascular death.

Though the Holter monitor is a common, noninvasive device, Stein says the software needed to measure heart rate turbulence is only available for clinical use on one commercial Holter monitor. She speculates that this work and other studies showing the value of measuring heart rate turbulence may make the software more widely available.

This work was supported by the National Heart, Lung, and Blood Institute and the National Institute of Neurological Disorders and Stroke.

The authors of:

Is there evidence for mandating electrocardiogram as part of the pre-participation examination?

discuss whether and EKG should be performed as part of all sports physicals.

They state:

“Pre-participation examination is by consensus understood to include personal history and physical examination; controversy exists regarding the usefulness and appropriateness of screening using resting 12-lead electrocardiogram (ECG), with an apparent transatlantic difference.”

Read some of the pros and cons of mandating a pre-sports participation electrocardiograms in the abstract on Angina.com

Reference:
Is there evidence for mandating electrocardiogram as part of the pre-participation examination?
Clin J Sport Med. 2011 Jan;21(1):13-7.
Borjesson M, Dellborg M.
From the Department of Acute and Emergency Medicine, Sahlgrenska University Hospital, Ostra, Sahgrenska Academy, Goteborg, Sweden.