primary pci | Dr.S.Venkatesan MD

Posts Tagged ‘primary pci’

Coronary hemodynamics in 100% occlusion ?

Posted in Cardiology - Clinical, Cardiology -Interventional -PCI, cardiology -Therapeutics, Cardiology -unresolved questions, cardiology- coronary care, Uncategorized, tagged 100% lad, 100% rca, chronic total occlusion, coronary artery, coronary collateral circulation, courage study, cto, des, europcr online, jacc, nejm, nstemi, oat study, open artery hypothesis, pci, plain balloon angioplasty, primary pci, ptca, scai, stemi, stents, tctmd, thrombolysis, toat study on July 15, 2009| 8 Comments »

Total coronary artery occlusion is a common finding in CAD especially in chronic stable angina. Normal coronary blood flow is 5 % of cardiac output that amounts to 250-300ml/mt.At an average heart rate of 70/mt , each beat injects about 5cc blood into the coronary circulation.This is shared between two coronary arteries. This means , only few CC (2-3cc) of blood enters each coronary artery with each cardiac cycle .

When one of coronary artery is totally occluded what happens to the coronary

blood flow ?

A.Total coronary blood flow can be be maintained normal at rest as it forms only about 5% of cardiac output (or it is only slightly reduced )

B. It is believed , the unobstructed coronary artery could receive the blood meant for the contralateral coronary artery. This possibly explains the increased coronary artery diameter in the non obstructed artery.

C. It’s nature’s wish , that the contralateral coronary artery shall share 50% of it’s blood through collaterals if available.

D.If collaterals are not formed it , the unobstructed coronary artery may be over perfused with double the amount of blood flow.

E. Some times , the collaterals steal much more than what the obstructed coronary artery deserves and make the feeding coronary artery ischemic. This is many times observed in total RCA occlusion with well formed collaterals from LAD/LCX.

F.The collateral flow in CTO also depend on whether flow is directed from LAD system to RCA or from RCA -LAD system. The LAD is better placed to assist RCA than vice versa.This is for two reasons.1.LAD blood flow is higher than RCA so it can share it.2.The driving pressure is more from LAD -RCA , as RCA can receive blood flow even during diastole .

F.During exertion , the coronary hemodynamics become further complex.The collateral’s are traditionally thought to be less than adequate during times of exercise.But it is more of a perception than solid scientific data.This rule may be applicable in only certain group of patients. We know CTO patients with very good exercise tolerance who have documented collateral’s.

G.Collaterals can be either visible or invisible by CAG. The strength of collateral circulation is not in it’s visibility but it’s capacity to dilate and respond to neuro humoral mediators at times of demand. Currently , there is lot to be desired regarding our knowledge about the physiology of visible collaterals , no need to mention about invisible collaterals !

Final message

The above statements are based on logics and observations .

Is it not a irony in cardiac literature , where thousands of articles are coming out every month to tackle totally occluded coronary artery(CTOs) , there is very little data regarding the coronary hemodynamics in chronic total occlusion . How does a patient with CTO can manage a active life with only one functioning coronary artery ?

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“Benefit of doubt” and the “risk of doubt” in cardiac care”

Posted in Cardiology - Clinical, tagged acs, annals of internal medicine, clinical dicision making, coroanry care, des, ebm, ethics, evidence based medicine, jama, nejm, nstemi, pci, primary pci, stemi, thrombolysis on June 19, 2009| Leave a Comment »

When a doctor is confronted by serious doubt , what will be the outcome for the patient ?

Can doubting be beneficial for a patient ? . It seems so , according to EBM which stresses about statistical outcome at every turn of events in a patient who is critically ill .

Is something , always better than nothing ? Our limbic system tends to think so . It may not be true. But in dire situations , many things (Proven , unproven) need to be tried however doubtful it ‘s efficacy may be .This is akin to an emergency in an airplane. Even here there need to be a logic.

Then ,this question arises . How do we make sure , we have a dire situation on hand ?

This is the key issue , in the decision making for the critically ill patients . It needs experience , only experience ! Though the principle of uncertainty is the fundamental rule in medicine , EBM aims to bring some degree of certainty in medical therapeutics.

Benefits of doubting in coronary care unit.

In a sinking patient with cardiogenic shock , try the maximum treatment . Even if , the patient is in severe shock , take him to the cath lab , try open the coronary artery . Give the benefit of doubt to him even though the chances of reviving him is less than 10%.

Risk of doubting in Coronary care unit.

A.Elderly STEMI with SHT,(Arriving late , with an unknown time window after an MI ) To thrombolyse or not ? . There is no benefit of doubt here. Do not thrombolyse. Here , apply the benefit of doubt against thrombolysis .

B. Chest pain with LBBB (Thought to be new onset LBBB ) don’t ever rush to thrombolyse. Wait for the enzyme result . Don’t try to thrombolyse your doubt , instead thrombolyse the confirmed thrombus !

C. Patient with persistent ST elevation following thrombolysis ,in an otherwise asymptomatic and stable patient. Don’t pass on ” your doubt ” of salvaging at least some myocardium by rescue PCI .Rescue should be done before death. You can not resuscitate dead myocytes.

Final message

The concept of giving the benefits of doubt to the patient is a widely prevalent practice in medicine .This concept is alive and popular , not because it has proved effective, but because of the primitive human perception and cognition , namely “Something is better than nothing ” !

Common sense and logic would suggest , whenever there is a benefit for doubting there would be a equal ( or even more ) unmeasured hazards and risks . This becomes especially true , when a physician makes a therapeutic move based on doubting than on conviction .

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Is there a low risk STEMI where primary PCI is contraindicated ?

Posted in cardiac drugs, Uncategorized, tagged acs, nstemi, p pci, primary pci, stemi, syntax, thrombolysis vs primary pci, tt vs p pci on June 14, 2009| Leave a Comment »

Primary PCI has proven to be the best option for management of STEMI . But it need to be done very early by a an experienced team in a good facility . (Note , it is not the individual expertise that matters ! Ronalodo alone can never guarantee a match win ! )

Any treatment , which has a great therapeutic potential also carries a hazard .

So , these treatment must be used with caution. Not every STEMI patient , has a high risk of death. In fact the mortality in some of the subsets of STEMI , can be less than 1%. If , a STEMI patient with a likely 1% mortality is going to get a procedure with 3-4% , risk it is bound to raise a validity question ?

What are the situations in STEMI , where primary PCI could be dangerous*?

* The term dangerous here means , Risk > Benefit .

Side vessel STEMI : STEMI in branch coronary arteries. Main vessel STEMI(LAD,RCA,LCX ) has higher risk than side vessel STEMI( Diagonals, OMs, Septal) .

Side vessel STEMI is not easy to diagnose in ECG , but an MI with ST elvation restricted to only 2 leads could be a side vessel STEMI.

The following could be some examples.

1 /AVL , High lateral
V2 V3 , Septal
3 AVF , PDA/RV/ Acute marginal
V5 V6 OMs/Ramus

A spontaneously evolving STEMI , with ST segment returning towards baseline and T wave getting inverted .This indicates IRA is either partially patent and the coronary blood flow is in the salvage mode. Here , thrombolysis is going to be very effective .

Final message

In the management of STEMI , primary PCI could be consciously avoided in some of the patients to improve the overall outcome .

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What is dfference between successful thrombolysis and successful reperfusion in STEMI ?

Posted in Cardiology - Clinical, cardiology -ECG, Cardiology -Interventional -PCI, cardiology -Therapeutics, Cardiology -unresolved questions, tagged aivr, myocardial reperfusion, no reflow, nstemi, primary pci, reperfusion, reteplase, stemi, streptokinsae, successful reperfusion, successful thrombolysis, tenekteplase, thrombolysis, tpa, what is successful thrombolysis on May 27, 2009| Leave a Comment »

Thrombolytic therapy , has been the specific treatment for STEMI for many decades. Primary PCI* is shown to be superior than thrombolysis if performed early by an experienced team in a dedicated facility. (*Conditions apply). It is estimated , currently only a a fraction STEMI population get primary PCI (<5%) in ideal conditions . Another fraction , get primary PCI by inexperienced cardiologists in low volume centres.

So , thrombolysis remains, and would continue to remain , the primary mode of therapy for STEMI in the present and near future !

How do you assess the successful thrombolysis ?

It should be recognised , there is a fundametal flaw in this question !

The aim of thrombolytic therapy is not to lyse the thrombus , but also to restore the coronary blood flow to the myocardium – also called reperfusion . One may wonder , why the term , thrombolysis should ‘t be used interchangeably with reperfusion.

A successful thrombolysis never guarantees a good reperfusion , for the simple reason , distal blood flow in an obstructed coronary artery is dependent on , many factors other than relief of obstruction.

Apart from the potency of drug, other important factors that determine successful lysis & reperfusion are . . .

Timing of opening of artery , if the thrombolysis is delayed , the distal myocardium is dead , and it won’t allow blood flow to enter the mycardium.
Microvascular integrity is as vital as epicardial vessels.
Distal microvascualture plugging by the thrombotic debri . This is called”no reflow “

So , we should primarily assess myocardial reperfusion rather than epicardial thrombolyis ! following thrombolysis .

What are the parameters available to assess successful reperfusion /thrombolyis?

Clinical : Relief from chest pain. Angina relief , though subjective is an indication for adequate reperfusion of ischemic myocardium.
ECG-ST segment regression > 50%
Cardiac enzymes: Early flushing of intra myocytic CPK into systemic circulation and hence early peaking of CPK MB (<1ohours instead of 24h)
Reperfusion arrhythmias(AIVR-Less specific) .Primary VF is now thought to be reperfusion related.
Infract related artery(IRA) patency by coronary angiogram
Distal TIMI flow/ myocardial blush score/ TIMI frame count

ECG ST regression , is a direct indicator myocardial reperfusion as the ST segment shifts towards baseline , implies of infarct current of injury . ST regression almost always correlate with good recovery of LV function in STEMI .

IRA patency , is an epicardial index , it does not give information about myocardial blood flow . But , a good distal TIMI flow generally indicates good reperfusion.This again , is not a fool proof index, as even many of the TIMI 3 flow patients have severely damaged myocardium by echocardiography .

Final message

For the above reasons, one should always make a distinction between successful lysis and successful reperfusion . Surprisingly , ECG is the gold standard for assessing successful reperfusion of myocardium , while CAG tell us about epicardial patency and possibly reperfusion also.

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Fallacies in emergency room :Why we are not risk stratifying STEMI on arrival , but do it promptly in NSTEMI ?

Posted in Cardiology -Interventional -PCI, cardiology -Therapeutics, Cardiology -unresolved questions, Cardiology-Coronary artery disese, tagged acc aha, acute coronary syndrome, angina, anterior mi, cardiogenic shock, coronary care unit, emergency triaging of chestpain, high risk nstemi, high risk stemi, inferior mi, is there a low risl stemi, jacc, LAD, left main, low risk nstemi, primary pci, RCA, stemi, thrombolysis, unstable angina, vulnerable plaque on May 21, 2009| 2 Comments »

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

ST elevation in V1 -V6 , 1 , AVL , Low blood pressure , with severe chest pain.
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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What is the most important criteria for doing a PCI in CAD ? The secret 6th criteria !

Posted in Uncategorized, tagged acc aha guidelines, acs, cabg, cath lab, chronic stable angina, cleaveland clinic, coronay revascularisation, courage trial, cypher stent, des, euoropct, flow limiting lesion, gruentzig, jacc, jama, left main disese, mayo clinic, nejm, nstemis, paclitaxel, pci, primary pci, proximal lad, ptca, ravel, scai, sirius, sirolimus, stemi, stent, stenting, syntax score, taxus, tct md, triple vesseldisease, wisdom trial on May 4, 2009| 1 Comment »

Scientifically , the indication for coronary revascularisation should be based on following

Patient’s symptom ( more specifically angina , dyspnea is less important !)
Prov0kable ischemia ( A significantly positive stress test )
Signifcant LV dysfunction with documented viable myocardium & residual ischemia
A revascularisation eligible coronary anatomy * TVD/Left main/Proximal LAD etc ( *Either 1, 2 or 3 should be present in addition )
All emergency PCI during STEMI /High risk NSTEMI

Practically ,

A CAD patient may fulfill “Any of the above 5 “ or “None of the above 5” , but , if a coronary obstruction was revealed by coronary angiogram and if he fulfils The 6th criteria , he becomes eligible for revascualrisation

6th criteria

If the patient has enough monetary resources (by self ) or by an insurance company to take care of PCI /CABG *

*The sixth criteria overrides all other criteria in many of the cath labs .Of course , there are few genuine ones still fighting hard , to keep the commerce out , from contaminating cardiology !

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What are the precautions to be taken during PCI when we encounter thrombus containing lesions ?

Posted in Cardiology -Interventional -PCI, cardiology -Therapeutics, tagged 2b 3a antagonists, acs, coronary dead space, coronary thrombosis, distal protection, drug eluting stent, expoert catheter, freed, ivus, pci, pci and thrombus, primary pci, ptca, stent approximation, tct md, thrombus and pci on March 22, 2009| Leave a Comment »

First and foremost is

Avoid the procedure if not really indicated.A lesion which has more thrombus load than a plaque and it is , subcritical and not limiting the flow , PCI may be inappropriate especially if the ACS is stabilised.

Adequate anticoagulation along with 2b 3a blockers should be used
Predilatation should be minimally used or to avoided.Direct stenting preferred.
In primary PCI suction devices (Export etc may be useful)
Distal protective devices are “hyped up devices” rarely useful in an occasional patient with good distal vessel diameter.
Pseudo stent approximati(fig 1) may occur. A Layer of thrombus may get plastered between stent and the vessel wall.In the post PCI phase , with intense anticoagulation and antiplatelet regimen this layer may get dissolved and stent may lose it’s grip and may dislodge or migrate.Another possibility is the dead space beneath the stent becomes a potential site for future thrombus and ACS.

Fig 1

To prevent this complication , high pressure inflations and Post procedure IVUS (Intra vascualr ultraound may be done to ascertain lack of thromus between stent/vessel wal interface)
Drug eluting stent evoked a special concern , when used in thrombotic milleu.This , has now been proven to be safe

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Critical cardiology : And now , drug abuse inside human coronary arteries !

Posted in Uncategorized, tagged acc.aha, acs, angioplasty, bmj, circulation, cypher, des, drug abuse, ethics, europcr, evidence based cardiology, long stent, medical auditing, nejm, nstemi guidelines, pci, primary pci, ptca, rescue pci, scai, sirius, sirolimus, stemi guidelines, stents, sub acute stent thrombosis, taxus, tctmd, thrombolysis on January 18, 2009| Leave a Comment »

Drugs are poisons , whenever it is administered without valid purpose. it can enter human body in many ways (Oral, intravenous, percutaneous etc ) And now we have another route namely intracoronary !

In quest for prevention of restenosis, many of the anti cancer drugs are now delivered directly inside the coronary arteries .These drugs are secreted like a sustained release tablet from the drug coated stents.These drugs are expected to prevent restenosis within the stented segment.But, after years of intense debate and research , we realised that , drugs eluted from the stent could damage the distal coronary vascular bed and coronary microcirculation.( And thus came the epidemic of acute stent thrombosis ! )

The tender and sensitive coronary microvasculature is constantly exposed to these powerful anticancer and immmunosuppresive drugs .It is a great surprise , no body thought of this dangerous drug -coronary artery interaction ! It required the genius of Renu virmani and others to point out this.

But still , the cardiology community by and large , fails to consider this an important issue.This is proven by the fact, usage of DES is still increasing and used mainly as an off label indication.

Read this land mark article from circulation

http://circ.ahajournals.org/cgi/content/full/115/8/1051?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=1&author1=renu+virmani&andorexacttitle=and&andorexacttitleabs=and&andorexactfulltext=and&searchid=1&FIRSTINDEX=0&sortspec=relevance&fdate=1/1/2007&tdate=12/31/2007&resourcetype=HWCIT