Severe blockage 2 years after 'normal' thallium stress test?

[Neener44]

My mom had a "normal" thallium stress at the age of 59 and then about 2 years later at the age of 61 ended up in the hospital on the verge of having a major heart attack and a cath was done which found 80% to 100% blockage in five major arteries. She was rushed in for emergency bypass surgery and is doing okay now. My question is, how could this have been missed on the thallium stress test? She had been having chest pain and pain in her left arm and had these symptoms during the test as well, yet they told her she was okay.

Thanks for this great forum and happy holidays to all.
Janeen

[CCF-M.D.-RCJ]

Janeen,

Thanks for the post, and sorry to read of your Mom's troubles.

Firstly, Thallium tests are about 80-85% sensitive for detecting CAD.  That still means that approximately 15/100 people with CAD who have a Thallium test will have a "negative" test.

Secondly, if your Mom had disease in almost all of her arteries, which sounds like what you describe, then she could have a condition called "balanced ischemia".  Thallium tests work by comparing one area of the heart with the others.  So if one area has a relative lack of blood flow, but the others don't, that area can be identified by the comparison.  On the other hand, if all the areas of the heart have a lack of blood flow, a comparison of one area with another will look similiar, thus leading to mis-diagnosis.

Other potential reasons exist, but are much less likely.

Your Mom's case illustrates why test results have to be incorporated with the entire clinical picture, and even then underdiagnosis can occur.

Hope that helps.

[Neener44]

Thanks so much for the explanation. You're awesome!
Janeen