T
TomS
Interesting article on EF. Before my AVR I was always getting copies of my Echo's (still do), and checking the EF, left ventricle dimensions, etc. playing amateur cardiologist. Here's the article:
Washington Post ? Tuesday, March 7, 2006
Learning Fractions
Experts Debate Wider Testing of Heart Risk Factor
By Elizabeth Agnvall
You already know your cholesterol, blood pressure, body mass index and blood sugar numbers. Now there's another predictor of heart health that some experts say certain people should learn: your ejection fraction, or EF. That's the percentage of blood pumped out to the body by the left ventricle, the heart's main pumping chamber.
The American Society of Echocardiography (ASE) recommended last week that people with a history of heart symptoms or heart attack and those who are at increased risk for heart disease ask their physician to measure their EF. Ensuring that it's at a safe level -- and getting treatment if it's not -- can help reduce the risk of sudden cardiac arrest, they say. Sudden cardiac arrest -- caused when an abnormal heart rhythm abruptly shuts off blood supply to the brain or other organs -- kills about 325,000 Americans every year, according to the American Heart Association. It occurs most frequently in men in their mid-thirties to mid-forties and causes half of all heart disease deaths
A normal EF is 50 percent or higher. That is to say, a healthy left ventricle empties itself of at least half its blood with each heartbeat. Several studies have linked an EF of less than 35 percent to an increased risk of sudden death or sudden cardiac arrest. People with an EF between 35 and 50 are also at risk and should consult with their physician about possible causes and treatments. Many people with a low EF have a weak or damaged heart muscle or a poorly functioning valve.
Ejection fraction is usually checked with an echocardiogram, but it can also be measured with an MRI, nuclear medicine scan or cardiac catheterization. But exactly who should be tested and what treatment they should receive in the event of a low EF score is stirring fierce debate among cardiologists.
Thomas Ryan, vice president of the ASE, said people with a low EF number are at risk for sudden cardiac death if their heart rhythms go out of whack. Evidence has shown, he added, that cardiac defibrillators -- battery-powered devices that are implanted by surgeons -- reduce such deaths by shocking the heart back into a normal pattern of beats.
"There have been several studies that have shown if you take patients with low EF and you give them a defibrillator, you reduce the risk of sudden death and actually improve outcomes in these patients," said Ryan, who is also the director of the heart center at the Duke University Medical Center in Durham, N.C.
One such study cited by the ASE was published in the New England Journal of Medicine last May. The study, involving heart failure patients with an EF of 35 percent or less, found that implantable defibrillators reduced the risk of sudden cardiac death by 23 percent over four years. Heart failure, often caused by weakened heart muscle, is marked by an inadequate flow of blood from the heart.
But lead study author Gust Bardy, professor of medicine at the University of Washington Medical Center, protested in an e-mail that his research was being misused in "an industry-sponsored initiative."
"My research is very specific, and what's happened is that it has been grossly abused by industry," Bardy said in an inteview. Before they received defibrillators, he said, the heart failure patients in his study had all been treated with medication -- such as beta blockers (drugs that slow the heart rate and lower blood pressure) and ACE inhibitors (drugs that help relax blood vessels) -- that can raise EF numbers. Only those for whom the medication did not work became candidates for the implants. Recommending EF tests for healthy people who merely have an elevated risk for heart disease, Bardy said, is "too simplistic."
The recommendation for EF testing comes as implantable defibrillator use has been rising dramatically. Last year, doctors implanted an estimated 162,000 devices, up nearly 20 percent from 2004 and more than triple the number in 2000, according to Harris Nesbitt, an investment firm. Domestic sales rose from $1.3 billion in 2000 to $5.6 billion in 2005.
Medicare's decision in January to expand coverage for the devices could cover more than half a million of the estimated 5 million Americans with heart failure, which suggests that defibrillator sales will continue to rise. Implanting one of the devices costs about $30,000; this surgery is usually covered by insurance. For echocardiograms, average costs range from $750 to $1,500. Medicare allows about $404 for these tests, according to the ASE.
Lynne Warner Stevenson, professor of medicine at Harvard Medical School and co-director of the advanced heart disease program at Brigham and Women's Hospital in Boston, sided with Bardy in calling the ASE advice "a bit of a leap."
She said even in most people at risk for heart disease, EF numbers aren't low before their first heart attack. Since about half of people who die suddenly of heart problems have no previous symptoms, she said, this type of screening wouldn't catch most of them.
"It's difficult to demonstrate that screening of patients who have no symptoms actually improves their outcome, because the studies are done on people who for some reason came to medical attention," she said. "As soon as you talk about going out into the community and screening at the shopping center, you're going to identify a different group of patients than those the therapy has been tested in."
She also expressed concern about moves to expand use of defibrillators, saying they benefit only one in 10 patients that have them.
"It is unseemly for us as a country to maintain that we can afford to put these devices in everyone with a low ejection fraction," she said. "We are the only country in the world that is claiming that we will do so."
Paul Heidenreich, associate professor of medicine at Stanford University, said measuring EF is a cost-effective way of discovering some heart problems. Heidenreich published a study in 2004 that found that screening in people with higher risk but without symptoms is cost-effective compared with other health interventions. But while treating low EF with medication is clearly warranted, he said, giving defibrillators to people without symptoms who don't respond to medication is questionable.
"If we were to identify people with very low EF but no symptoms, a lot of people would be unclear about what to do," he said.
Steven Goldstein, director of the Noninvasive Cardiology Laboratory at the Washington Hospital Center, said people who have heart disease or symptoms linked to heart attacks, arrhythmia or heart failure should get an echocardiogram and go on medication if their ejection fraction is lower than 40 percent. He said the decision about whether a patient needs a defibrillator is highly complex and depends on many factors, including the patient's age, the severity of the disease and whether arrhythmias are present.
He cautioned that there is a danger of overuse if doctors assume that everyone who has a low EF needs a defibrillator. Too much alcohol, cocaine, some viruses and even pregnancy can lead to a low EF that is reversible.
Richard Page, head of cardiology at the University of Washington School of Medicine, said before implanting a defibrillator in a low-EF patient, doctors should rule out reversible causes and consider medication that might improve the function of the heart.
Often, though, a defibrillator may be the best solution, he said.
"If you do the math, there will be a lot more [defibrillators] placed, but there will also be a greater number of lives saved."
Goldstein said he hopes that as more research is done, cardiologists can determine which patients with a low EF need the device and which do not.
"I don't think anyone advocates doing an [echocardiogram] routinely with simple risk factors like smoking, diabetes, high blood pressure," he said. ·
Washington Post ? Tuesday, March 7, 2006
Learning Fractions
Experts Debate Wider Testing of Heart Risk Factor
By Elizabeth Agnvall
You already know your cholesterol, blood pressure, body mass index and blood sugar numbers. Now there's another predictor of heart health that some experts say certain people should learn: your ejection fraction, or EF. That's the percentage of blood pumped out to the body by the left ventricle, the heart's main pumping chamber.
The American Society of Echocardiography (ASE) recommended last week that people with a history of heart symptoms or heart attack and those who are at increased risk for heart disease ask their physician to measure their EF. Ensuring that it's at a safe level -- and getting treatment if it's not -- can help reduce the risk of sudden cardiac arrest, they say. Sudden cardiac arrest -- caused when an abnormal heart rhythm abruptly shuts off blood supply to the brain or other organs -- kills about 325,000 Americans every year, according to the American Heart Association. It occurs most frequently in men in their mid-thirties to mid-forties and causes half of all heart disease deaths
A normal EF is 50 percent or higher. That is to say, a healthy left ventricle empties itself of at least half its blood with each heartbeat. Several studies have linked an EF of less than 35 percent to an increased risk of sudden death or sudden cardiac arrest. People with an EF between 35 and 50 are also at risk and should consult with their physician about possible causes and treatments. Many people with a low EF have a weak or damaged heart muscle or a poorly functioning valve.
Ejection fraction is usually checked with an echocardiogram, but it can also be measured with an MRI, nuclear medicine scan or cardiac catheterization. But exactly who should be tested and what treatment they should receive in the event of a low EF score is stirring fierce debate among cardiologists.
Thomas Ryan, vice president of the ASE, said people with a low EF number are at risk for sudden cardiac death if their heart rhythms go out of whack. Evidence has shown, he added, that cardiac defibrillators -- battery-powered devices that are implanted by surgeons -- reduce such deaths by shocking the heart back into a normal pattern of beats.
"There have been several studies that have shown if you take patients with low EF and you give them a defibrillator, you reduce the risk of sudden death and actually improve outcomes in these patients," said Ryan, who is also the director of the heart center at the Duke University Medical Center in Durham, N.C.
One such study cited by the ASE was published in the New England Journal of Medicine last May. The study, involving heart failure patients with an EF of 35 percent or less, found that implantable defibrillators reduced the risk of sudden cardiac death by 23 percent over four years. Heart failure, often caused by weakened heart muscle, is marked by an inadequate flow of blood from the heart.
But lead study author Gust Bardy, professor of medicine at the University of Washington Medical Center, protested in an e-mail that his research was being misused in "an industry-sponsored initiative."
"My research is very specific, and what's happened is that it has been grossly abused by industry," Bardy said in an inteview. Before they received defibrillators, he said, the heart failure patients in his study had all been treated with medication -- such as beta blockers (drugs that slow the heart rate and lower blood pressure) and ACE inhibitors (drugs that help relax blood vessels) -- that can raise EF numbers. Only those for whom the medication did not work became candidates for the implants. Recommending EF tests for healthy people who merely have an elevated risk for heart disease, Bardy said, is "too simplistic."
The recommendation for EF testing comes as implantable defibrillator use has been rising dramatically. Last year, doctors implanted an estimated 162,000 devices, up nearly 20 percent from 2004 and more than triple the number in 2000, according to Harris Nesbitt, an investment firm. Domestic sales rose from $1.3 billion in 2000 to $5.6 billion in 2005.
Medicare's decision in January to expand coverage for the devices could cover more than half a million of the estimated 5 million Americans with heart failure, which suggests that defibrillator sales will continue to rise. Implanting one of the devices costs about $30,000; this surgery is usually covered by insurance. For echocardiograms, average costs range from $750 to $1,500. Medicare allows about $404 for these tests, according to the ASE.
Lynne Warner Stevenson, professor of medicine at Harvard Medical School and co-director of the advanced heart disease program at Brigham and Women's Hospital in Boston, sided with Bardy in calling the ASE advice "a bit of a leap."
She said even in most people at risk for heart disease, EF numbers aren't low before their first heart attack. Since about half of people who die suddenly of heart problems have no previous symptoms, she said, this type of screening wouldn't catch most of them.
"It's difficult to demonstrate that screening of patients who have no symptoms actually improves their outcome, because the studies are done on people who for some reason came to medical attention," she said. "As soon as you talk about going out into the community and screening at the shopping center, you're going to identify a different group of patients than those the therapy has been tested in."
She also expressed concern about moves to expand use of defibrillators, saying they benefit only one in 10 patients that have them.
"It is unseemly for us as a country to maintain that we can afford to put these devices in everyone with a low ejection fraction," she said. "We are the only country in the world that is claiming that we will do so."
Paul Heidenreich, associate professor of medicine at Stanford University, said measuring EF is a cost-effective way of discovering some heart problems. Heidenreich published a study in 2004 that found that screening in people with higher risk but without symptoms is cost-effective compared with other health interventions. But while treating low EF with medication is clearly warranted, he said, giving defibrillators to people without symptoms who don't respond to medication is questionable.
"If we were to identify people with very low EF but no symptoms, a lot of people would be unclear about what to do," he said.
Steven Goldstein, director of the Noninvasive Cardiology Laboratory at the Washington Hospital Center, said people who have heart disease or symptoms linked to heart attacks, arrhythmia or heart failure should get an echocardiogram and go on medication if their ejection fraction is lower than 40 percent. He said the decision about whether a patient needs a defibrillator is highly complex and depends on many factors, including the patient's age, the severity of the disease and whether arrhythmias are present.
He cautioned that there is a danger of overuse if doctors assume that everyone who has a low EF needs a defibrillator. Too much alcohol, cocaine, some viruses and even pregnancy can lead to a low EF that is reversible.
Richard Page, head of cardiology at the University of Washington School of Medicine, said before implanting a defibrillator in a low-EF patient, doctors should rule out reversible causes and consider medication that might improve the function of the heart.
Often, though, a defibrillator may be the best solution, he said.
"If you do the math, there will be a lot more [defibrillators] placed, but there will also be a greater number of lives saved."
Goldstein said he hopes that as more research is done, cardiologists can determine which patients with a low EF need the device and which do not.
"I don't think anyone advocates doing an [echocardiogram] routinely with simple risk factors like smoking, diabetes, high blood pressure," he said. ·
