DURHAM -- Thousands of patients may undergo heart catheterizations without having any blockages that would warrant the invasive diagnostic test, researchers at Duke University Medical Center report today.
The study, published in the New England Journal of Medicine, found that up to 60 percent of patients without a history of heart disease are essentially free of clogs when they undergo cardiac catheterizations. Expensive and potentially risky, the procedures could often be avoided if less invasive diagnostic tools were more effective.
"The question is: Is there a better way to do this?" said Dr. Manesh Patel, a cardiologist at Duke University Medical Center and lead author of the study.
It's a multimillion-dollar question. As the health care debate rages in Washington, concerns about the proper use of technology and medical procedures have emerged, particularly as they drive up the nation's $2.3 trillion tab for health expenditures.
"Whenever you have expensive procedures, there's the concern that some of them will be unnecessary," said Thomas Hoerger, a health economist at RTI International in Research Triangle Park. "The problem is knowing which are unnecessary. Better screening or pre-surgery differentiation of patients can help, but it's hard just to say cut the number of catheterizations by 60 percent."
Each year in the United States, an estimated 1.5 million patients have heart catheterizations, which are the gold standard in detecting blood vessel blockages that can cause heart attacks.
Costing between $10,000 and $30,000, depending on complications, the procedure is a model of sophisticated medical technology.
Often conducted in special labs, catheterization involves opening a blood vessel in the arm or leg to route a thin tube into the heart. Dye is injected through the tube, highlighting blockages on imaging machines in what's called an angiograph.
For people such as William Brimley, 58, of Roxboro, the procedure is a life-saver. Brimley has severe heart disease, and the catheterization confirmed doctors' suspicions that new clogs had built up in vessels cleared two years ago during a triple-bypass surgery.
Brimley had his workup at Duke, where he was attended by a team of four - Patel, a nurse and a technician in the procedure room, plus a computer operator sitting a room away. A swiveling X-ray machine automatically zoomed in over Brimley's chest to capture the best angle for pictures. Monitors blinked in the control room.
But that level of sophistication may be overblown for many others.
Early tests misleading
Patel's study involved nearly 400,000 U.S. patients who had no known heart disease but had elected to get heart catheterizations, often after experiencing chest pain or an unusual heart rhythm.
Nearly all those patients - 84 percent - were given a noninvasive screening such as an electrocardiogram, a CT scan or a stress test. Most of those exams came back positive, suggesting a cardiac catheterization was warranted.
When the procedure was done, however, only 38 percent of the patients actually had blockage, about 40 percent had no blockages, and the remainder had minor clogs.
Patel said the problem is not with cardiac catheterizations but with the noninvasive exams that precede it. Ideally, those tests should keep healthy people from undergoing an expensive procedure that puts them at risk for serious complications, including stroke and heart attack.
"The interim steps need to be improved," Patel said. In addition, he said, more needs to be done to establish a consistent threshold from stress tests and other diagnostic procedures before triggering a catheterization.
"That's a national discussion," he said. "It's hard to tell a patient they have an abnormal [stress] test, and some risk, but they don't need to go to the cath lab."
He said many patients opt to have a catheterization so they can get definitive answers. If minor blockage turns up, Patel said, it often motivates patients to modify their diets and exercise, so there are some benefits to the trend.
Still, he said, the better alternative would be to have more sensitive noninvasive diagnostic tools.
To that end, he said, the Duke team next month will begin enrolling patients in a four-year study comparing two noninvasive diagnostic testing strategies - stress tests and coronary computed tomographic angiography, a newer imaging technology that is gaining popularity.
The study, which will include 10,000 patients nationwide, will assess how effective the diagnostic tools are, and whether they improve patient outcomes.
"In this time of health care reform, we have to ask what's the best way to see who has blockage," Patel said. "There's a new wave of ideas to figure out new ways of getting people a diagnosis. We have a lot of work still to do."
