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Posts Tagged ‘acute coronary syndrome’

NSTEMI constitutes a very heterogeneous population .The cardiac risk can vary between very low to very high . In contrast , STEMI patients carry a high risk for electro mechanical complication including sudden death .They all need immediate treatment either with thrombolysis or PCI to open up the blood vessel and salvage the myocardium.

The above concept , may be true in many situations , but what we fail to recognize is that , STEMI also is a heterogeneous clinico pathological with varying risks and outcome !
Let us see briefly , why this is very important in the management of STEMI

Management of STEMI has undergone great change over the past 50 years and it is the standing example of evidence based coronary care in the modern era ! The mortality , in the early era was around 30-40% . The advent of coronary care units, defibrillators, reduced the mortality to around 10-15% in 1960 /70s . Early use of heparin , aspirin further improved the outcome .The inhospital mortality was greatly reduced to a level of 7-8% in the thrombolytic era. And , then came the interventional approach, namely primary PCI , which is now considered the best form of reperfusion when done early by an experienced team.

Inspite of this wealth of evidence for the superiority of PCI , it is only a fraction of STEMI patients get primary PCI even in some of the well equipped centers ( Could be as low as 15 %)

Why ? this paradox

Primary PCI has struggled to establish itself as a global therapeutic concept for STEMI , even after 20 years of it’s introduction (PAMI trial) . If we attribute , lack of infrastructure , expertise are responsible for this low utility of primary PCI , we are mistaken ! There are so many institutions , at least in developing world , reluctant to do primary PCI for varied reasons.( Affordability , support system , odd hours ,and finally perceived fear of untoward complication !)

Primary PCI may be a great treatment modality , but it comes with a inherent risk related to the procedure.

In fact the early hazard could exceed the potential benefit in many of the low risk STEMI patients !

All STEMI’s are not same , so all does not require same treatment !

Common sense and logic would tell us any medical condition should be risk stratified before applying the management protocol. This will enable us to avoid applying “high risk – high benefit” treatments in low risk patients . It is a great surprise, the cardiology community has extensively researched to risk stratify NSTEMI/UA , it has rarely considered risk stratification of STEMI before starting the treatment.

In this context , it should be emphasized most of the clinical trails on primary PCI do not address the clinical relevance and the differential outcomes in various subsets of STEMI .

Consider the following two cases.

Two young men with STEMI , both present within 3 hours after onset of symptoms

  1. ST elevation in V1 -V6 , 1 , AVL , Low blood pressure , with severe chest pain.
  2. ST elevation in 2 ,3, AVF , hemodynamically stable , with minimal or no discomfort .

In the above example, a small inferior MI by a distal RCA occlusion , and a proximal LAD lesion jeopardising entire anterior wall , both are categorized as STEMI !
Do you want to advocate same treatment for both ? or Will you risk stratify the STEMI and treat individually ? (As we do in NSTEMI !)

Current guidelines , would suggest PCI for both situations. But , logistic , and real world experience would clearly favor thrombolysis for the second patient .
Does that mean, the second patient is getting an inferior modality of treatment ?

Not at all . In fact there is a strong case for PCI being inferior in these patients as the risk of the procedure may far outweigh the benefit especially if it is done on a random basis by not so well experienced cath lab team.
(Note : Streptokinase or TPA does not vary it’s action , whether given by an ambulance drive or a staff nurse or even a cardiologist ! .In contrast , the infrastructure and expertise have the greatest impact on the success and failure of PCI )
Final message

So , it is argued the world cardiology societies(ACC/ESC etc) need to risk stratify STEMI (Like we do in NSTEMI ) into low risk, intermediate risk and high risk categories and advice primary PCI only for high risk patients.

Reference

https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/226907

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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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                             Glucose is the molecule of life   ,burnt every second inside the body at the energy store house called mitochondria. Heart , the most active organ in the body  gets  bulk  of it’s energy supply  from fatty acids,  glucose and a little from keto acids. Under anerobic conditions this energy substrates shifts towards glucose .

                             We are  rarely inclined to think  that heart  can ever suffer from hypoglycemia ! But hypoglycemia can have distinct direct and indirect effects on heart.  In fact indirect effects due to activation of adrenergic activation is more obvious.An episode of hypoglycemia can precipitate an arrhythmia . Glucose potassium insulin infusion

 

 

 

Final message

Hypoglycemia , can be a trigger of ACS .This aspect is poorly recognised and studied.

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