Those who answered “Yes” , can leave this article . Those who answered “No” read further .
* Logic would tell us myocardial revascularisation should correct stress induced ischemia and it should disappear promptly . This does not happen in all cases real world ! That is why medicine is different from mathematical science .
Some of the reasons for persistence of stress positivity even after an apparently successful PCI are . . .
- Incomplete correction of ischemia. (Ideally to be referred as failed PCI )
- Error in Identifying culprit 9Angina related artery ) .Common feature of poorly worked up multivessel CAD.
- Re-stenosis /Re-occlusion
- Doing very early stress test without giving time for revascularisation to work *
- Rapid progression of non culprit lesions .(Sub -optimal medical management )
- Chronic N0-Reflow phenomenon surrounding area of infarct .(Especially in PCI of CTOs)
- Dyskinetic or grossly remodeled ventricular segments can result in non ischemic positive EST response (ST drag **)
- Associated systemic conditions especially Anemia/ SHT & LVH -(False positive )
- Many diabetic patients may continue to show stress ischemia due to small vessel disease.
- A patient with syndrome X characters can have incidental epicardial lesion as well . In such a patient EST will always be positive .
* Optimal time to do EST for assessing the efficacy of PCI/CABG is not established .Six months may be the reasonable point .If done within 2- 3 months it may end up in embarrassment for the Interventionist . (So only it is kept at 6 months , this also help us greatly as we can always blame it on poor life style control and progression of the disease !)
** No reference for this , a personal observation .We know Q leads following MI , will show ST elevation during stress test especially if the segments are dyskinetic . In leads diagonally opposite to q leads , ST depression is observed . This may not be a evidence for true ischemia . It probably represents ST drag due to mechanical stretch .
Dr.S.Venkatesan MD 