Computed tomography angiography is booming. In 10 painless minutes, this noninvasive test provides a detailed, colorful three-dimensional view of a patient's heart. Many specialists say the CT procedure is more accurate and precise than other heart tests.
Exact figures aren't available, but some experts think Americans undergo several hundred thousand CT angiographies a year, perhaps more than a million.
"It's a very easy test to do," says Dr. Michael Lauer, a heart researcher at the National Heart, Lung and Blood Institute. The test is "proliferating," he says.
That, critics say, is a problem. They call the procedure untested, overused, risky and a prime example of health care ruled by profit and fad rather than hard science.
The debate has intensified since January, when the federal agency that oversees Medicare proposed tight restrictions on insurance reimbursement for CT angiography, a technique that relies on multiple X-rays to create a three-dimensional image of internal organs.
The test typically costs $1,000 to $1,200, more than many patients can pay on their own. So the agency's move would significantly reduce its use. Because many insurance companies follow Medicare's lead, the agency's final decision, due next month, could affect the entireindustry.
"It would have a major effect" on the number of patients who get the test, says Dr. Sean Tunis, director of the Center for Medical Technology Policy.
His San Francisco-based group is an independent nonprofit that studies the ways new medical procedures are tested. Until 2005, Tunis, who lives in Baltimore, was chief medical officer of the Centers for Medicare and Medicaid Services, the agency that oversees Medicare.
Since the CMS proposed the change, cardiologists, radiologists and other doctors who use CT angiography have flooded the agency with appeals.
"This test has huge promise," says Dr. Armin Zadeh, a cardiologist at Johns Hopkins University School of Medicine. "For the first time, we are able to non-invasively see coronary artery disease."
CT angiography arrived a decade ago, and its use has grown steadily. It is one of a growing number of tests that use computed tomography. The Food and Drug Administration oversees CT scanners but does not regulate their day-to-day use.
"CT angiography has revolutionized the way doctors treat heart disease," says Andrew Whitman,vice president of the Medical Imaging & Technology Alliance, a medical-imaging trade group. "The evidence is well established."
Despite the test's appeal and popularity, many researchers say CT angiography has not been adequately studied.
"We have a technology that takes really nice pictures," says Dr. Rita Redberg, a cardiologist at the University of California, San Francisco. "But we have absolutely no data on whether it actually helps patients."
As a result, some argue, many patients get the test unnecessarily. Stephen R. Baker, a professor of radiology at New Jersey Medical School, estimates that at least half of CT angiographies are unnecessary.
Critics also note that CT angiography typically delivers a radiation dose equivalent to hundreds of standard X-rays. They say the dose could significantly increase a patient's risk of some cancers, particularly thyroid cancer.
All CT scans, not just angiography, expose patients to significant radiation. Recent studies have argued that these scans - more than 60 million a year - might cause millions of cases of cancer in coming decades.
Baker worries that many patients and doctors don't understand the radiation risks involved in CT angiography.
"Radiation is a toxin," he says. "It seems obvious that if you give a patient a toxin, then some harm will be done."
He attributes much of the test's popularity to the fee-for-service system, which pays doctors for performing and interpreting tests. "These tests enrich the people who read them," Baker says. "When you get paid for every study, you want to do more."
Zadeh, who orders about 15 CT angiographies a week, says CMS' proposed limits could cost lives. He sees the test as less risky than cardiac catheterization, a longtime standard for diagnosing many heart problems.
In such catheterizations, a doctor inserts a tube into an artery in the groin and threads it up to the heart. Typically, the tube is filled with dye that makes the heart and blood vessels visible to an X-ray. One of every 435 patients who undergoes the procedure has a heart attack, a stroke or dies.
This week, Zadeh performed a CT angiography on Lori Nauman, 50, an office manager and lifetime smoker from Chase. A recent checkup revealed a weak heart. Zadeh wanted to check the arteries around her heart but also wanted to avoid a catheterization because he suspected that the vessels were fine.
Lying on the CT table, Nauman said she was not worried about radiation. That didn't surprise Zadeh, who said, "I haven't met any patients who wouldn't prefer the CT angiography over the cath."
As Zadeh watched, three radiology technicians adjusted the CT machine - a new model that takes 960 pictures a second (most take fewer than 200) and delivers the equivalent of two to three times a person's average yearly radiation dose. Older machines typically deliver at least five times the yearly dose.
Within minutes, the machine produced a sharp color image of Nauman's heart. The verdict: no damage and no need for catheterization.
Concerned about radiation risk and unnecessary costs, CMS wants to limit reimbursement for patients who are at intermediate risk for coronary artery disease, a common heart problem in which blood vessels around the heart are narrowed or blocked. Such patients would be reimbursed only if part of a study to evaluate CT angiography.
Risk categories are determined by a formula based on age, blood pressure, lifestyle and ailments such as diabetes.
The proposal would "significantly restrict coverage if it goes through," says Dr. Marcel Salive, CMS' director of medical and surgical services.
There is no conclusive evidence that intermediate-risk patients get any benefit from CT angiography, he says, hence the need for the studies. Those in high-risk groups don't need a CT angiography because they are clearly sick, Salive says. And low-risk patients don't need the CT angiography because the dangers from radiation outweigh the potential benefits of the test.
Zadeh said he understands CMS' concern and agrees that some patients might be receiving unecessary CT angiographies. But he says the agency is throwing the baby out with the bathwater.
"You have to put this in context. Every test is a weighing of risks and benefits," he says. " The CMS thing has the potential to really damage the field. In years to come, this test will be the cornerstone of heart imaging."
david.kohn@baltsun.com