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Posts Tagged ‘failed thrombolysis’

Less than a century ago an easy chair  was enough to manage this most important medical emergency of mankind. Of course, at that time mortality of STEMI was estimated to be around 30%.We have since pushed the in-hospital death rate down to less than 10 %  and its around 5-8% currently.(*The lifeless chairs were able to save 70 lives is a different story!)

Heparin , thrombolytic agents, critical coronary care has helped us to achieve this , of course It must be admitted primary PCI also played a small role (at best 1 % ) in our fight against this number one killer.

Now, why not combine  both lysis and PCI ?

The concept of PIA (Pharmaco Invasive approach) came into vogue  primarily for two reasons.

1.If thrombolysis and  pPCI are powerful strategies by individual merits why not combine both and achieve double the benefit ?

2. Since pPCI is going to be a logistical nightmare in most points of care and we can’t afford to lose time . So, let us lyse first and consider PCI later !

Unfortunately medical science is not math .One plus one in medicine is rarely two !

Though , it looks attractive , Pharmaco invasive approach  has its own troubles.Fortunately , most of them are man-made, few are beyond our knowledge though.

Following general rules  may help us

  • STEMI  should ideally managed by early thrombolysis (or PCI) in all deserving patients.
  • Don’t wait for PCI if you think , there will be delay or reduced expertise and poor track record of the center in this modality.
  • Pharmaco invasive  therapy is not a default in all STEMI .Do good quality , monitored  lysis , (Not necessarily new generation thrombolytic .(I prefer one hour sustained thrombolytic regimen , not the hit or miss bolus) .As a learned cardiologist we need to assess individual patients according to the type and risk of MI.Its not wise to blindly follow the guidelines ,because these guidelines , though based on evidence never answers a query in a single patient perspective !

The key “branch points”  in decision making  after lysis

  • Invasive strategy  should begin within one hour if the patient has failed  thrombolysis and has developed any mechanical issues.( Mind you, LVF requires good medical stabilization .Rushing  such patients to cath lab without application of mind can be disastrous )
  • If the Initial  lysis is excellent and the patient is asymptomatic  one need not proceed with invasive limb at all.(A significant chunk of apparently failed lysis by ECG are asymptomatic and comfortable , these are patients require delicate assessment regarding further intervention. )
  • If the MI is large and the clinical  stability is “not confirmed” one may  proceed urgently within 24 h.
  • In any case there is no role for invasive approach after 24 hours* Unless fresh ischemia  suspected to come from IRA or  non IRA.
  • Having  said that, there are many centers that do a diagnostic  angiogram alone just prior to discharge  (48-72h) for risk stratification and then take a genuine call for a possible PCI or  CABG. In my opinion it appears a sensible strategy , though a non invasive stress  test pre/post discharge can even avoid that  coronary angiogram !

One issue with Rescue PIA

Though by current definition  PIA is to be done  3-24 hours , don’t wait for the 4th hour if you have recognized a failed thrombolysis earlier than three hours.( Ofcourse , as the gap between P and I gets too narrowed it may  carry some adverse  effects witnessed in routine facilitated PCI -Refer FINESSE study ) Similarly,there need not be a blanket ban on PCI beyond 24 hours if residual ischemia is active.

Final message

PIA is a dynamic  coronary  re -perfusion strategy . Nothing is fixed in science. . The optimal gap between Pharmaco and invasive strategy  can be anywhere between  1 hour to “Infinitely deferred” depending upon individual risk perception and wisdom of the treating cardiologist.

 

 

 

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           Do not ever under estimate  the importance of  TIMI 1 flow .  It can save a  major chunk of myocardium !   A late TIMI 3  flow   . . . is far inferior . . .  to  an early TIMI 1 flow . * Even a trickle  of  flow (Ooze )   can keep the myocardium  alive .  This point we have realised very late. Thus came the   pharmaco Invasive strategy for  all STEMI  who have no immediate access to cath lab ! (please note 90 % of STEMI belong to this group )

pharmaco invasive strategy for stemi002

For a high resolution Image  click below

pharmaco invasive strategy in stemi

* Even a trickle (Ooze )   blood flow can keep the myocardium  alive .

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Failed thrombolysis is a well debated concept, while failed primary PCI is a conveniently neglected phenomenon .

How to assess successful reperfusion following PCI or thrombolysis?

I do not know how many  of us know this vital fact !

Coronary angiogram is squarely beaten by the humble  ECG in assessing the effectiveness of myocardial  reperfusion . This is not hard to understand as  coronary angiogram *  can  tell us only  about epicardial  patency ,  while ECG  sends vital perfusion  data from within the  myocytes ! Which do you  think is superior ?

And now  interventional cardiologist have realised this fact . they  measure the ST segment  regression instantly once the primary  PCI is  completed . How ?  An ECG is recorded from  right inside the infarct  related artery .

*Of course myocardial blush score , TIMI frame count are poor alternatives !

This paper just published in CCI is  a fascinating revelation .

http://onlinelibrary.wiley.com/doi/10.1002/ccd.23455/abstract

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Which is  the most important factor that determines thrombolysis failure in STEMI  ?

  1. Thrombus load .
  2. Drug efficiency
  3. Time delay
  4. Presence of a mechanical lesion
  5. Hemodynamic instability

Answer : 3 .(Though all 5 factors operate )

Failed thrmbolysis occur in about 40-50% after streptokinase and slightly less with TPA   and TNK-TPA . Delayed arrival and late thrombolysis are  most common cause of failed thrombolysis. As the time flies , the  myocardium gets damaged and the intra coronary  thrombus gets organised .Both these processes make delayed thrombolysis a futile exercise.

               Not all STEMI patients have large thrombus burden. There need to be a critical load of thrombus for thrombolytic to be effective

Some may have a major mechanical lesion in the form of plaque fissure, prolapse and it simply blocks the coronary artery mechanically like a boulder on the road  . The poor  streptokinse  or the rich Tenekteplace !  nothing can move this boulder .The only option here is emergency PCI .

How will you know when the patient  arrives in ER with STEMI whether his/ her coronary artery is blocked with soft thrombus or hard mechanical boulder ?

It is impossible to know.That’s why primary PCI has a huge advantage.  But still thrombolysis is useful as some amount of thrombus will be there in all patients with STEMI.Lysing this will provide at least a  trickle of  blood flow that will jeep the myocardium viable and enable us to take for early PCI.

Final message

The commonest cause for thrombolytic failure is the time of administration and the degree of underlying mechanical lesion  . So  it does not make sense  to blame  streptokinase always !

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We know prompt reperfusion of infarct related artery( IRA) by any means  constitute the specific management of  STEMI .However, It needs  to be emphasized ,  treatment process of STEMI  is not over after  primary  PCI or thrombolysis .Early hours after a PCI or thrombolysis  is vital as well .The ill-fated coronary arteries are as  vulnerable as before.  In the setting of multi-vessel CAD  (Which usually is the case) the unpredictability is still more.

Image courtesy New york times , January 5 , 2009

When a patient complaints of chest pain  24 hours after a STEMI . Think about any of the possibilities and act accordingly.

  1. Infarct related pain ( Dull aching pain from residual neural signals from infarct zone,  till type C  un-medullated  nerve endings  die of hypoxia )
  2. Post infarct angina –From IRA zone (Residual ischemia)
  3. Post infarct angina-From Non IRA zone(New Remote ischemia)
  4. Re-Infarction
  5. Infarct expansion/ Extension /mechanical stretch
  6. Pericarditis
  7. Intra coronary dissection adjoining  a plaque (Plaque fissures  are same as dissections if they extend into media ! But plaque fissures are painless since they lack nerve endings  )
  8. Myocardial tear /Rupture (Generates  severe pain , usually transmit to back , patient often become violent and poorly respond  even to narcotics)
  9. Post resuscitation/DC shock / chest wall contusion . ( I know at least one patient  who was rushed to cath lab for a  suspected  acute stent thrombosis  ,  it was indeed   a rib fracture during an  earlier resuscitation at ER  on his arrival !)
  10. Finally ,when the  pain is refractory and atypical   non cardiac chest pain which might have been pre existing to be considered as remote possibility .

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How early one can shift a patient for rescue PCI after failed thrombolysis ?

  1.  Wait for at-least 24  hours.
  2. A minimum  cool off period of 2 hours is required.
  3. It is never an issue . Rush the patient  immediately to cath lab
  4. The question does not arise  . Often times ,  rescue PCI is a dead concept  as  sufficient damage has happened !

Answer

The irony of  medical science  lies in our belief that every medical query  has a specific answer ! In reality it is rarely true.   In this instance , any of  the above can be a correct response.

A patient with  failed thrombolysis can belong to any of the  64 possible combinations*  based on  time of  thrombolysis , extent of  MI,  associated complications, co- morbid conditions , presence of symptoms . (For example there is  a sub groups of patient with  failed thrombolysis still  asymptomatic  and comfortable )

The issues for rescue PCI  do not  arise  in a   sinking STEMI (Cardiogenic shock ) , or  STEMI with persistent angina. There  is  no  management issues in  these patients  .They need to be rushed to cath lab. Unfortunately  in  impending  LVF or manifest LVF (But not in shock )  decision making is tough , as doing a PCI in patients  with basal crackles  and hypoxia is a real challenge .These are the patients who are likely  to hit hard  from the hazards of the procedure .Extreme caution is required.

I have seen  significant cohort  of  asymptomatic hypotensive patients getting converted into   drug resistant, IABP dependent refractory shock after PCI  ,  making every one look  pathetic  !  The  only solace for the interventionist  is  the gratification  of  stenting the  IRA !

This  happens  , in spite  of having  multi national trained  in house critical care anesthetics and  dual core processing IABP  . Realise  what we need is delicate decision making ,  So use extreme diligence in selecting patients with impeding shock .

Your medical management can  provide  more teeth to stabilise your patient than a PCI .If you are doubt discuss with your learned colleagues .  ( If you  do not  ask for evidence for  this statement , probably  it would confirm  you  as  an  experienced   cardiologist  !)

Real issues pushed to the sidelines ?

While the real issue  in the timing of rescue PCI  may be  different , the discussion traditionally  revolves around   hemo-rheological aspects . We know  the lytics and PCI do not combine well for two reasons.

  • Pro-coagulant nature of lytic state .
  • Excess bleeding risk at puncture site.

Now ,  we have evidence to say fibrin specific lytics  TPA, TNKTPA has less of this issue . ( NORDISTEMI)

Patients who receive  fibrin specific lytics  can  safely  be  taken for rescue PCI  in case it is needed without any increased risk .

Bleeding complication  has dramatically reduced as radial procedures are done often even in emergency setting.

Vascular occlusive devices  have added to our comfort.

* The definition of failed  thrombolysis by  itself is not standardized . Is it symptom guided ?  or ECG / enzyme / echo guided  ? A patient with  infarct  related chest pain (dull aching )  after thromolysis can be labeled as post infarct refractory angina and rushed for emergency angiogram .(This is due to our ignorance  about  the  residual pain signals  through  type c pain fibres  for up to 24 hours )

Final message

The indication and  timing of rescue PCI is  primarily  related   to the  overall   patient profile  rather than the bleeding or pro-coagulant issues .

Although   pro-coagulant  lytic state is based on weak scientific  foundation , it  is a blessing in disguise  as it  can  act  as a deterrent  in restricting  inappropriate rescue PCI !

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