Posts Tagged ‘st depression’

The most common ECG dilemmas one encounters is to differentiate between the ST segment depression and T wave inversion due to LVH from that of primary ischemia.

Very often  , the entity is misdiagnosed . The implication can be serious , and adding further complexity is exercise stress testing is alos prone for errors in these group of patients as false negative or positive results are very common due to basline  ST/T changes.So it needs a CAG to confirm or rule out CAD in many .

Still the clinical acumen with the help of ECG can help us to a great extent !

A rough and approximate way to identify primary ischemia is given below.

Though these  humble ECG features may not be specific to diagnose CAD . One  need to remember even a normal coronary angiogram is  not synonymous with normal coronary arteries !

Read this blog on limitations of CAG .

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                                Acute coronary syndrome (ACS) is currently classified as STEMI and NSTEMI.This classification came into vogue  primarily to  triage patients for thrombolysis eligibility , as ST elevation is the  only criteria for thrombolysis.The  earlier term  non q MI  is largely used  to denote the  present day NSTEMI. In the past q  MI was referring to transmural MI non q MI  to non transmural  pathologically.(Of course , now we know  the relationship between q waves and transmurality is not good )

So when can we still use term non q MI ?

These terminologies of STEMI and NSTEMI are made on admission  at the emergency room.  ACS being a dynamic entity these  patients can  have rapidly changing  ST shifts , from depression to elevation and vice versa. Fresh T wave changes can also occur .Q waves  may or may not develop ,  depending upon the damage sustained to the myocardium and the efficacy of thrombolysis / PCI. So it should be emphasised here STEMI,  NSTEMI ,  q  MI ,  non q MI are the  descriptions of the  same group of patients in different time frames. The common mode of  evolution  of  STEMI  is  to q MI and NSTEMI  into non q MI. Cross overs can occur.



 The problem here is NSTEMI getting converted into STEMI  is quiet common and has no nomenclature issues . But  when   STEMI down grades  into NSTEMI  there is apparent  nomenclature incompatibility .This category of  patients have  no other labelling option other than “A STEMI evolving into non q MI”. Because one can’t label  STEMI  evolving into NSTEMI as  many of  them  will  have a residual ST elevation as well.

What is the final message ?

The term non q MI is still relevant and is used at discharge , in a patient with STEMI when he or she evolves without a q wave .In the setting of unstable angina , NSTEMI has largely replaced  the term  non q MI either on admission or at discharge.

Before I close

                 The important point to remember here  is NSTEMI getting converted into STEMI  is an adverse outcome and  in fact, it is  a complication and the patient should get an immediate  thrombolysis or PCI , while a STEMI getting converted into non Q MI is generally a  major therapeutic success.( Effective salvaging and preventing q waves )


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