Thursday, July 31, 2008
Monday, July 7, 2008
The Controvery Over Cardiac CTAs
Image via WikipediaA few minutes later, Dr. Hecht studied the results. As he had expected, the angiogram revealed that Mr. Franks’s arteries were healthy. In some places, plaque had blocked 25 percent of their blood flow, but in general, cardiologists do not consider blockages clinically relevant until they reduce blood flow at least 70 percent.The article attempts to reconcile two sharply opposing points of view. In my opinion — and I hasten to add that I'm not a cardiologist or radiologist — cardiac CTAs are at the same level of clinical usefulness and acceptance now that CTAs of the pulmonary arteries were several years ago. It took years for a CTA of the pulmonary arteries to a widely accepted test for diagnosing or excluding pulmonary emboli. Within the next several years, I would expect that CTAs of the coronary arteries will become a well-accepted test for diagnosing or excluding coronary disease.
After Mr. Franks finished dressing, he joined Dr. Hecht, who went over the results, explaining that his heart appeared healthy and that he would not need a stent. Still, Dr. Hecht recommended that Mr. Franks have another CT angiogram next year to check that the plaque was not thickening. Mr. Franks agreed, pronounced himself satisfied and left.
For Mr. Franks, the test was quick and painless. But it subjected him to a significant dose of radiation.
Based on a reporter’s notes about the duration of the scan and the power output reported by the scanner, Dr. Brenner of the Center for Radiological Research estimated that Mr. Franks had received 21 millisieverts of radiation — even more than a typical test, equal to about 1,050 conventional chest X-rays.
Given the radiation risks, Dr. Ralph Brindis, another cardiologist, said Dr. Hecht had erred. Because Mr. Franks had already taken a nuclear stress test with normal results, he did not need a CT angiogram, said Dr. Brindis, vice president of the American College of Cardiology. And particularly because the scan’s results were benign, he said, Dr. Hecht should not have recommended a follow-up test.
“The biggest problem we have with radiation is that the doses are cumulative and additive,” Dr. Brindis said. “So the concept of doing serial CT testing on asymptomatic patients, I think, is abhorrent. I cannot justify that.”
Dr. Hecht said he sharply disagreed with Dr. Brindis. The scan was appropriate for Mr. Franks, despite his normal results from the nuclear stress test, because of Mr. Franks’s other risk factors for heart disease, including his higher-than-average calcium score, Dr. Hecht said. And he said he recommended a follow-up scan next year so he could see how quickly the plaque in Mr. Franks’s arteries was thickening.
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