Angioplasty: No Effect on Future Heart Attack
Posted by medconsumers on April 1, 2006
Dramatic Rise in Cardiac Procedures, But Heart Attack Rate Stays Constant
Over the last 10 to 15 years there has been a dramatic increase in cardiac procedures in the U.S. and Canada. Coronary artery bypass surgery and artery-opening procedures are intended to restore blood flow to the heart in order to prevent heart attacks. One might reasonably expect each country’s rate of heart attack to show an equally dramatic decline. But the heart attack rate stayed relatively constant in both countries. The findings came from two studies, one in the U.S. and one in Canada, published in the January 24 issue of the journal Circulation. They appear to validate the longstanding, but widely ignored, research indicating that today’s cardiac surgeons are still operating on an outmoded understanding of heart disease.
Each country’s study drew on claims data from its publicly funded Medicare program to determine the cardiac procedure rate. Medicare in the U.S. primarily covers people age 65 and over, while Medicare in Canada covers everyone, though the study looked solely at adults in Ontario. At the start of the study period, Canada’s rate of cardiac procedures was lower than that of the U.S., but both countries showed similar massive increases. The researchers determined the heart attack rate by looking at the claims submitted by people hospitalized for a heart attack during a 15-year period in the U.S. study and a 10-year period in the Canadian study.
“There are a couple of different messages for consumers in our study,” said F. Lee Lucas, PhD, Center for Outcomes Research and Evaluation, Maine Medical Center, the lead author of the American study. “The increased rates [of bypass surgery and artery-opening procedures] over time likely mean that doctors are quicker to intervene for milder and milder symptoms, particularly in white men,” she noted in a telephone interview. Dr. Lucas explained that the data collected in her study did not allow conclusions to be drawn regarding the percentage that might have been unnecessary.
David Waters, MD, who was not involved in either study, was less reticent about their implications. “We can assume that that these procedures are not influencing the heart attack rate, and some may be unnecessary,” he said in a telephone interview. Dr. Waters is chief of cardiology at San Francisco General Hospital and professor of medicine at University of California, San Francisco.
The two studies also indicate that an outmoded understanding of heart disease still dominates the way it is treated. According to the so-called new view of heart disease, a major constriction in the coronary artery is not where a future heart attack will occur. “There’s lots of data to show that opening a narrowed artery will not reduce your chances of having a heart attack,” said Dr. Waters, citing the one exception. “If, however, a person is having a heart attack, and that person has an artery-opening procedure while having the heart attack, there is good evidence that this will reduce the risk of dying of that heart attack.” In other words, the procedure will have no effect on future heart attacks.
The old model for the development of a heart attack is based on heart disease as a plumbing problem. The metaphor, which is still served up to the public to explain heart attacks, goes like this: A coronary artery slowly becomes narrowed with plaque in much the same way a pipe becomes corroded with rust and other gunk. In time, the artery becomes so constricted that blood flow to the heart is eventually shut off with a blood clot.
New Mechanism for a Heart Attack
The new understanding of heart disease is far more complex and is based on the observation that the vast majority of heart attacks do not occur in the portion of the artery that is most obstructed. Instead, most heart attacks occur where plaque breaks off and a clot forms over the area that can abruptly stop blood flow to the heart. In this scenario, the plaque is soft, symptomless, and would not be seen as an obstruction to blood flow. Heart disease is an inflammatory process by which the coronary arteries are subjected to a constant cycle of irritation, injury, healing and reinjury that makes the plaque likely to rupture. The solutions are the standard prevention advice: stop smoking, and take drugs to reduce clotting, inflammation, blood pressure and cholesterol.
If the new view of heart disease has been around for more than a dozen years, why hasn’t this changed the way it is treated? Do heart surgeons know about it? “The interventional cardiologists know about it, but they ignore it,” answered cardiologist Thomas Graboys, MD, in a telephone interview. “A new breed of over-trained cardiologists has now flooded into the community,” said Dr. Graboys, professor of medicine at Harvard Medical School and president of the Lown Foundation. It is no longer the large urban-based academic medical centers that come overstocked with interventional cardiologists. They have now come to the community hospital near you. And there is a strong financial incentive for them to look for constricted arteries and open them. “Economics drive the train,” said Dr. Graboys. “The starting salary of an interventional cardiologist is $300,000-400,000 a year, and for one that has been in practice three years, it is $500,000 to $600,000.”
Dr. Waters also sees money as the driving force. “If you have chest pain and the cardiologist you see does coronary angiography (see sidebar below) and that pays for his kids to go to college; well, are you are more likely to wind up with that procedure?” He advises, “Get a second opinion from a cardiologist who is not in the same building, the same group, or the same hospital as the first opinion cardiologist.” Dr. Waters also suggests that people give careful thought to the type of cardiologist chosen for a second opinion. There are, he explained, regular cardiologists who prescribe drugs; interventional cardiologists who do cardiac catheterizations, artery-opening procedures and stenting; and cardiovascular surgeons who perform coronary bypass surgery. The received opinion will likely mirror the doctor’s area of expertise.
The number of people undergoing artery-opening procedures continues to rise not only because they are huge money-makers but they are also very effective at relieving the severe chest pain of angina, which is a common symptom of heart disease. They are virtually useless, however, in stopping the progress of the disease itself. “The public is looking for a magic bullet,” observed Dr. Graboys, who offered this advice to people who are not in an acute situation. “Go to a non-hospital-based doctor in the community. A well-trained internist can take care of the lion’s share of people with coronary heart disease. The vast majority of people do well on medication—cholesterol-lowering drugs, antihypertensives, low-dose aspirin.”
Still, clogged arteries cannot be good. Won’t they eventually close off? “The body performs its own bypass,” explained Dr. Graboys, describing what is often seen during cardiac catheterizations. “The body forms new blood vessels around the constricted area, thus restoring blood flow.”
Dr. Graboys knows whereof he speaks; he is a cardiologist at the Lown Cardiovascular Center in Brookline, Massachusetts, a second opinion consultation center affiliated with Brigham and Women’s Hospital. For over two decades, the Center has helped many people avoid unnecessary surgery. Long before others made this connection, Dr. Graboys began to see the stress test and cardiac catheterization—two diagnostic procedures—as somewhat akin to a conveyer belt that funnels people to an artery-opening procedure or bypass surgery. A constricted artery is discovered, often several (not at all unusual in anyone over age 55), and the person goes on to what doctors call “a cascade of interventions”. In fact, the odds are so high that a cardiac catheterization will set people on to this course of events that Dr. Graboys advises a second opinion before agreeing to it.
A second opinion is all the more important given that Dr. Lucas, the lead author of the American study, said her data suggest that the threshold for deciding who is a candidate for an artery-opening procedure has been lowered over time. “Rates of bypass surgery have leveled off. This is due to the fact that bypass surgery is clearly the more invasive procedure requiring prolonged anesthesia and use of a heart/lung machine, etc., but with artery-opening procedures you’ve got the person in the cath lab, and you’ve got that catheter in there already; it’s tempting to go ahead and do the procedure, so the threshold for performing the procedure might be lower than it would be for bypass surgery,” Dr. Lucas explained. “Many people who have had it done firmly believe that it saved their lives, but the benefit of most procedures is [solely] control of symptoms.”
What does all this mean to the average older person who suspects that one day he or she might wind up in an emergency room with chest pains? To Dr. Waters, the people who show up in the emergency room with severe chest pain are the ones most likely to require an artery-opening procedure. “The person I worry about is the person who goes to the doctor with a vague symptom and finds himself with a doctor who is not skilled at distinguishing the important symptoms of a heart disease from other symptoms.”
Asked for an example of a vague symptom that an unskilled physician might mistakenly identify as heart-related: “I was recently playing catch with my dog and now have shoulder pain,” he responded, suggesting that this could be enough to start the cascade of interventions. It is, in fact, common for symptom-free people to be told to have a stress test and this alone can start the cascade.
The cascade may be worth it, if all these cardiac procedures were lifesaving, but so far proof is lacking. “There is no evidence to show that artery-opening procedures will prolong life,” said Dr. Graboys, citing the exception of a person in the midst of a heart attack. “Although these procedures are good at alleviating the heart-related chest pain called angina, so too are drugs and lifestyle changes.” Dr. Graboys continued, “Data show that people with angina can be treated successfully with medicines and lifestyle changes like stress reduction, regular exercise, smoking cessation, and treatment of risk factors like high cholesterol and high blood pressure.”
For more information on different types of angioplasty, see below.
The U.S. study led by F.L. Lucas, PhD, was supported in part by a grant from the National Institute of Aging. The Canadian study led by David A. Alter, MD, PhD, was supported in part by a grant by the Heart and Stroke Foundation of Canada.
Maryann Napoli, Center for Medical Consumers ©
Cardiac Procedures Explained
Cardiac catheterization is a general term for a group of procedures involving a thin tube (catheter) inserted into a blood vessel in the groin or arm. The catheter is threaded up to the coronary arteries andpositioned either in the chambers of the heart or at the arteries supplying the heart. Once the catheter is in place, the doctor can inject a special dye or fluid that is visible by x-ray. This produces motion x-ray pictures called an angiogram, which are used to diagnosed the health of the coronary arteries. Other names for cardiac catheterization are coronary angiography and coronary arteriography.
This diagnostic technique becomes therapeutic once the doctor decides to widen a constricted artery in another procedure called angioplasty. This can be done in several ways. The plaque can be pressed against the walls of a constricted artery with an inflated balloon at the tip of the catheter. In the currently most popular version of angioplasty, tiny wire cages called stents are used to destroy the obstruction and keep the constricted artery open. In the new study by Dr. Lucas and colleagues, artery-opening procedures were grouped under the name of percutaneous coronary interventions.
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