In this politically and scientifically uncertain world nothing is in black and white. How can you expect EST to behave differently ?
Even as we are fully aware of the limitations of EST , it does not make sense to categorize EST result into either positive or negative .
In fact , our estimate suggests a significant bulk of the patient would fall in the grey zone .
It is referred in various terms by the reporters of EST .
- Borderline positive
- Mildly positive
- Equivocal
- Inconclusive
What does all these terms mean to the patient ?
It mans only one thing . . .
Physician who reports the EST is unable to conclude whether his patient has significant CAD or not . It is a dignified way of expressing the limitations .
Many factors may play a role. (See the illustration above )
- Patient factors : Poor exercise stress levels and conditioning
- Lesion factors: Collateralised CAD, treated CAD can result in partial or mild changes.
- Machine factors :Caliberation errors.
- Interpreter : (Physician ) factors
Error in measurement of ST segment . What is borderline for one doctor may indeed be true positive for the other and vice versa .
How will be the EST in a revascularised or medically treated CAD ?
If revascularization is a complete success , stress test would revert back to normal or it can be a borderline as we have just mentioned.
To our surprise , it may remain positive in spite of apparently successful procedure.(Residual wall motion defects , scar mediated ?)
How to proceed after this borderline EST/TMT ?
Few options are available for the physician/patient
Talk with the patient again , assess the baseline risk of CAD if it is low ignore the TMT result and reassure.
- Repeat stress test after a month.
- Stress thallium
- Doubutamine stress
- CT angiogram
- Regular Cath angiogram* (May be the best , of course it also carries a risk of labeling the condition as mild CAD / non critical CAD etc )
For the patient the easiest option may be , self referral to a different cardiologist . (Also called second opinion )
Final message
There is indeed an entity called borderline EST . Do not dare to ignore it or else face the consequences .
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