Angina is the classical clinical counterpart of myocardial Ischemia.
True Ischemia , by electro- physiological rules must elicit some sort of ST segment shift .(Usually ST depression rarely Elevation )
But . . . we know Ischemia and ST depression do not always go together ! Dissociation can occur in both ways.
ST depression without angina is more prevalent (often referred to as silent ischemia) , while angina without ST depression is less common but by no means rare .
We observe both these phenomenon during EST. The critical issue here is , any pain without ST depression during a EST , the physician is likely to reject it as non cardiac.
How wise it is , to ignore such chest pain ?
If a patient complaints true compressive , squeezing pain it should be taken as angina and EST should be stopped and labelled as positive even without ECG changes .
According to the much famed (De ) theory on ischemic cascade chest pain is supposed to come last. Time and again the rule of ischemic cascade goes awry in the bed side. Clandestine angina without any ECG evidence be more important clinical entity than we realize.
The argument against this , “If you start believing patient’s word more than ST depression then the very purpose of EST documentation is lost !
According to the now de-famed theory on ischemic cascade , chest pain is supposed to come last. Time and again the rule of ischemic cascade is found to go awry in the bed side .Clandestine angina without any ECG evidence be more important clinical entity than we realize.
Another clinical situation where we encounter ST segment : Angina dissociation is , during balloon inflation of PTCA.
Two explanations can be offered for Angina in the absence of ECG changes .
1 .Cancellation of ST vectors due to ischemia of two diagonally opposite areas of ischemia.
2. Electrical blind spots in 12 lead ECG. This is especially common with LCX ischemia where most of the electrical events are directed to back of the chest.Conventional leads can easily miss .