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What is being rescued in rescue angioplasty ?

Posted Oct 18 2009 10:02pm

Rescue angioplasty as a concept in PCI is advocated for the past  two decades. Rescue angioplasty  continues to enjoy the  controversy over the years. A procedure which fails to shrug off the controversy for so long   inspite of multiple studies ,  would indicate there is something seriously wrong in the  procedure  or in the conceptualization.

The fundamental question   that  is often  and not answered properly is :

What is being rescued in R angioplasty ?

Is it the

  • Patient’s life ?
  • Myocardium  ?
  • Rescues ischemic myocytes
  • Infarct related  artery ?

*Or it simply rescues physician  from the legal issue arising out of  labeling his patient as  failed thrombolysis

The term rescue generally implies  tackling an  impending crisis .The threat is either  to the patient’s life or to the myocardium or both.

In STEMI when the initial reperfusion strategy fails (Usually thrombolysis)  R -angioplasty is considered. Here the aim is  to  rapidly  rescue  and salvage  myocardium . The problem  here is   , contrary to our expectation   the population of failed thrombolysis is not a homogenous one .In one end of the spectrum ,  is a patient with  persistent ST elevation ,   totally comfortable and pain free and  hemodynamically stable.The other end is , deteriorating blood pressure , tachycardia , progressive angina and impending cardiogenic shock. Considering the above situations it is very simple to guess who will  require the rescue  and  who will benefit more. In fact,  R -angioplasty  in   patients with  asymptomatic  failed thrombolysis  without ongoing  ischemia defies logic and conveys no meaning !  .This is especially true if the patient has crossed 12 hours of time since the first symptom.

In deteriorating patients R- PCI has a role where one can potentially  arrest the progression of cardiogenic shock  or even reverse it.

A third  group  among failed thrombolysis have  predominate  angina  with  hemodynamic stabilty. This group will benefit from R angioplasty  irrespective of time window , as the pain is often due to a critical non IRA lesion .Technically again we can’t call this PCI as rescue as nothing is done to salvage the myocardium . (Of course one wish to call it so ,  as the  patient is rescued from angina !)

A tricky issue is to know where does the pain come from in a post MI patient ?

It should be realised a post MI patient can have variety of source of chest pain. There has been instances where a persistent  pericardial pain has resulted in emergency  R-PCI !

The critical question that  has not  been  answered by cardiologists is

How long a STEMI pain last and when doespost infarct angina begin in a  susceptible patient .

In other words how do differentiate present(Index event)  infarct angina from post infarct angina ?

Studies on pain signal transmission (medullated type c)  would suggest a dull aching retrosternal pain may occur in a substantial number of  patients  following STEMI .These pain signals come from  necrosed cells and not from  ischemic cells. This pain ceases after complete  ischemic destruction of nerve endings . The threshold , duration and central perception of this pain is highly variable.

One can imagine the importance of the above issue ,  as   there is a potential  to  misdiagnose recurrent post MI angina   for the relatively benign infarct related pain. Though experience have suggested a 12 hour cut off to define post MI angina ,  it is too empirical .

Final message

  • Rescue angioplasty remains as a  disputed entity in vast majority of  post MI population .
  • It is most useful when  it is done in  impending cardiogenic shock .Note the word. Impending not established cardiogenic shock. (After prompt recognition of failed thrombolyis within  overall time window <6h  ideally ,  but may be done  to up to 12h)
  • There is no role for routine rescue in all failed thrombolysis patients , for the simple reason there may not be any clinical or  live myocardial  targets for rescue.
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