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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:
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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