Re: Thallium Stress Test

Posted By CCF CARDIO MD - MTR on June 28, 1998 at 23:20:20:

In Reply to: Thallium Stress Test posted by Ellen on June 24, 1998 at 15:29:03:






I had a thallium stress test.  The interpretation was "mild degree of
anterior wall reversible ischemia consistent with coronary artery disease".
The doctor at that time said it was "of some concern".  In a later
report of his, he said that it was a false positive result.
Another doctor looked at the test and suggested that it was breast artifact.
The first doctor never said anything about breast artifact, just "of some
concern", then, "false positive".  
Are false positives common?  Does it bear re-checking?
Thanks.



   _
Dear Ellen, thank you for your question.  False-positive stress thallium results
are common and can occur at a rate of 10-15%.  Common causes of false-positive
tests include breast attentuation of the images, conduction abnormalities of the
heart, and disorders that reduce the pumping function of the left ventricle
(called cardiomyopathies).  In a stress test, a radioactive tracer is injected
into the blood at rest and during peak exercise to evaluate blood flow to the
heart muscle.  If a significant blockage is present in a coronary artery, an
area of muscle that has normal blood flow at rest may have reduced flow at
peak exercise (termed reversible ischemia).  Breast attentuation occurs when
the breast tissue blocks transmission of particles from the tracer to the camera that
overlies that patient.  In this situation, the anterior wall of the left ventricle
that lies just behind the left breast may appear to have reduced perfusion when
there may be no blockage at all.  The images from the stress test are interpreted
by physicians and it's possible for two physicians to disagree on the same images.
In your case, I cannot determine whether you need a repeat stress test or any
other tests.  However, I suggest that you see your physician again and express
your concerns about the ambiguity regarding the results of your stress test and
what the follow-up plans are.  I hope you find this information useful.
Information provided in the heart forum is for general purposes only.  Specific
diagnoses and therapies can only be provided by your physician.

[upen374]

A related discussion, interpretation of stress thalium test which I have gone through atleast 4 times, antiography three times and anigioplasty once. Can the blockages occur time and again? was started.