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Sensitivity of CT Scans for the Coronary Arteries May Lead to Unnecessary Surgery

Posted Nov 28 2011 12:00am

The ordering of CT scans is now being closely scrutinized as to whether the procedure is being overutilized (see: Medicare Claims Show Overuse for CT Scanning ; Treat the Patient, Not the CT Scan ; Major Increase in CT Scans in Hospital Emergency Departments ). Now comes news of a  study suggesting that the use of coronary computed tomography angiography (coronary CT scans) may lead to unnecessary surgery due to the excessive sensitivity of the procedure (see: New Heart Disease Test Brings Higher Costs and More Procedures ). Here is an excerpt from the article:

[C]oronary computed tomography angiography...uses CT scans to visualize patients’ coronary arteries and has become increasingly popular in the past five years. Previous methods for testing for heart disease involve an exercise-based stress test using ECG (electrocardiography), cardiac perfusion scans or other readings. The sensitivity of the newer approach, however, might also prove to be its weakness. “If you pull a 75-year-old off the street and give him the test, it’s unlikely that the coronary arteries will be completely normal,” ...said [the co-author of a study] in a prepared statement. But whether a slightly abnormal reading indicates a level of sickness that should necessitate surgery, such as catheterization or revascularization, is one of the big questions at hand for this and many other diagnostic advances. In a study of more than 282,800 Medicare beneficiaries who received non-invasive testing for heart disease between 2006 and 2008, only about 3 percent received the newer CT-based screening. Those who did receive this form of screening, however, were more than twice as likely to later receive coronary catheterization and two and a half times more likely to undergo cardiac revascularization when compared with those who were tested with profusion scans. These CT patients were similarly more likely to undergo these procedures as those who had gotten ECG-based tests....The findings don’t suggest scrapping the higher-tech test, but the take-away message is that this, and many other new tests should be evaluated to see if they are really improving life for patients in the long run.

New types of CT and MRI imaging keep coming to the forefront. What may not be keeping pace are studies that focus on whether the changes detected by these new imaging studies result in the overdiagnosis of disease (see: Sports Medicine Said to Overuse M.R.I.’s ). Perhaps better stated, the question needs to be asked when and if the detection of minimal disease by imaging studies warrants medical or surgical intervention. Here is a quote from a previous note on overdiagnosis (see: The "Overdiagnosis" Problem in Our Health Delivery System ):

[O]ne physician-author has studied [the] problem [of overdiagnosis] (see: Health Blog Q&A: H. Gilbert Welch, Author of ‘Overdiagnosed’ ). [Here] is an excerpt from a blog note about him and his ideas:

...Welch and co-authors...write about the hazards of looking too hard for conditions or illnesses in healthy people, including additional procedures that carry no benefit but may cause harm, higher health-care costs and the psychological impact of being told you’re sick. ....But the reality now is that we can find abnormalities in just about everyone and that can start a whole train of harmful events. So we all need to adopt a more balanced approach. Overdiagnosis doesn’t necessarily lead to overtreatment, but it often does.

At least in my mind, the increased use of CT and MRI is becoming inextricably linked to overdiagnosis and overtreatment. I am not sure how to counteract this phenomenon other than to promote more research such as the study cited above, Unfortunately, such research takes time and, meanwhile, the use of a new imaging procedures may become entrenched in clinical practice.

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