Published May 24, 2011
When symptom-free people have heart scans to look for clogged arteries, they can end up with overtreatment and side effects, researchers said Monday.
In a study published in the Archives of Internal Medicine, they found people who had the scans were much more likely to be put on medications and undergo surgery than those who chose standard health screening.
The scans, called coronary computed tomography angiography or CCTA, produce a detailed image of the heart that reveals cholesterol buildups in the coronary arteries.
If they get big enough, such buildups may cut the blood flow and cause a heart attack. So in theory, treating them early on might help stave off some the more than 1.2 million heart attacks -- a third of them fatal -- that occur every year in the U.S.
Yet there's no evidence that treating people based on heart scan results does any good, said Dr. John McEvoy, of Johns Hopkins Ciccarone Center for the Prevention of Heart Disease in Baltimore, who led the new study.
By contrast, it's well known that the scans expose patients to a high dose of X-rays, which can increase their likelihood of developing cancer. And the dyes used to enhance the images cause kidney damage in a significant portion of people.
"Testing might lead to more harm than good," McEvoy told Reuters Health, adding that heart scans may cost $600 or more.
His team looked at 1,000 Korean patients who chose to get a heart scan as part of a health screening program at Seoul National University Bundang Hospital.
The researchers compared those patients to closely matched individuals who opted to forgo the scans—not currently recommended by guidelines—and just get the standard health checkup.
More than a fifth of the patients who got scanned had cholesterol buildups in their arteries, also called atherosclerosis.
Three months later, these individuals were using cholesterol-lowering statins 34 percent of the time and blood-thinning aspirin 40 percent of the time. In those who tested negative for atherosclerosis or didn't get scanned, less than 10 percent used the medications.
People who got scans also had more additional tests and major heart procedures.
The researchers expected that if the extra drugs and procedures were actually helpful, the treated people would have a lower rate of serious heart problems in the future.
But after another 18 months, there was no such difference. There was just one event in the 1,000 people who had CCTA (one case of hospitalization for chest pain) and one in the 1,000 people who didn't (a heart-related death).
Currently, whether a patient gets statin or aspirin is based on risk factors such as their age, and how much cholesterol is in their blood. Both drugs have side effects, notably joint problems and bleeding ulcers.
Although the study can't prove that getting a scan caused the extra medication use, the gap could not be explained by differences in risk factors for heart disease, such as cholesterol levels or smoking.
In an editorial, Dr. Michael S. Lauer of National Heart, Lung, and Blood Institute in Bethesda, Maryland, said the new study serves as a reminder of the downsides of screening.
"Physicians cannot easily ignore diagnoses made with screening tests because it is impossible for them to determine whether their patients have real disease or pseudodisease," Lauer notes. "Therefore, physicians prescribe tests, medications, procedures, or even surgical procedures, all of which carry inherent risks."
McEvoy agrees. "With these new imaging techniques, we are left with the dilemma of what to do with the results," he said.
Even when screening helps predict health problems down the road, Lauer adds, that doesn't mean treatments are necessarily beneficial.
"Overdiagnosis is threatening to become an increasingly important public health problem because of the enthusiasm for and proliferation of unproven screening tests," Lauer writes.
McEvoy said there have been several reports of doctors doing CCTA heart scans in healthy patients, although the practice is currently discouraged by the American Heart Association.
According to McEvoy, doctors should focus on patients' lifestyle and traditional risk factors such as smoking and obesity.