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November 30, 2008 -- 6:30pm EST

Popular Press Continues to Breed Confusion Over CT Heart Scans
I scanned (pun intended) the current health news today and came up with the following assortment of reports about a study that was published, along with an accompanying commentary, in this week's New England Journal of Medicine:

• Scientists doubt utility of CT scan as heart test (Reuters)
• Hopkins study supports use of CT scan of heart (Baltimore Sun)
• Heart Scans Sometimes Fail to Identify Blockages, Study Finds (Wall Street Journal)
• CT scans seen as accurate, safe alternative to cardiac angiography (Los Angeles Times)

Confused? Of course you are. And the correct headline depends on your point-of-view...and your agenda: a perfect example of the Rashôman effect.

The study in question reports the results of an international multicenter trial (CorE 64) conducted by the team of imaging specialists at Johns Hopkins, and is titled "Diagnostic Performance of Coronary Angiography by 64-Row CT". The data originally were presented a year ago at the American Heart Association annual meeting (Angioplasty.Org covered that presentation in our article, "64-Slice CT Heart Scan Gets High Marks As Test for Blocked Arteries") and the data showed that CT angiography had very high predictive value for diagnosing coronary artery disease. The CorE 64 study was partly funded by Toshiba Medical Systems, a manufacturer of CT scanners.

The accompanying and critical commentary, published by the NEJM as a "Perspective" piece, is titled, "Pay Now, Benefits May Follow — The Case of Cardiac Computed Tomographic Angiography" and is co-authored by Dr. Rita Redberg of UCSF. In this op-ed piece, Dr. Redberg continues her critique of CT angiography as being an unproven and unnecessary test -- a view that she last voiced via a June New York Times article. Dr. Redberg's disclosures show that her work is supported by the insurer, Blue Shield of California Foundation.

So, on the surface, it seems to be a conflict between the imaging industry and the medical insurers. But I find that, in the case of CT angiography, this adversarial relationship is a straw man. For example, the accuracy of CT angiography could potentially eliminate many invasive angiograms, one third of which are negative, thus significantly reducing costs and complications for patients.

Also, the Reuters article states categorically that "the amount of radiation received with a CT heart scan is double, triple or quadruple the exposure in conventional angiography." Perhaps that was true years ago. But today the typical CT scan is the same as or less than conventional angiography. Not so for the very often used nuclear stress test -- which in fact does expose the patient to double or triple the radiation.

This is a complex subject and I will be dealing with it in more detail on Angioplasty.Org. Check the news page later this week.

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