Posts Tagged ‘guidelines’

Fundamental principle  of  human biological system is to live in harmony with nature and environment.Each cell  has a unique reaction  when it comes into contact with  external  material. This reaction can be acute or chronic  ,   local or systemic. The most severe form of allergy is called anaphylaxis  that can result in instantaneous loss of life. There  is a whole gamut of disorders  that  resulted  in a  separate  speciality called allergic medicine .

Further ,the transplantation  science have   taught us  an  organ or cell can be rejected at any point of time after implantation (Hyperacute -chronic) .With advancement of science we have started implanting a variety of devices  with complex metallurgy ,inside human body, metal clips, prosthesis, valves, wires, etc .How the body handles them .The consequences can be a mild reaction to major ones occasionally.

Consider ,a local allergy due to a orthopedic prosthesis  in one of the leg bones  is far less serious than a metal within a coronary artery  irritating the intima .

Remember hypersensitivity reactions can be severe . This lady reacted  like this to a sandal slipper -A  fiery red  infiltration

contact dermatits stent allergy pci coronary

Imagine  if a stented coronary artery react like this what would be the possible consequence ?

In susceptible  individuals  , can a metal cause

  • Intimal hyperemia
  • Intimal induration
  • Intimo-medial edema  following stent deployment

pci stent coronary angiogram thrombosis des

Why drug eluting stents are more prone for hypersensitivity ?

The answer is simple , while metal allergy is a comparatively rare phenomenon, the drugs we  coat and the polymers used are  many fold likely to result in hypersensitivity reaction.

While  the world is worried  more  about penicillin , sulpha allergy which occurs in 1 in 100000 ,  we tend to ignore the metal and drug  reactions within  the tender coronary arteries.

stent des rejection virmani  pci

What is  the clinical expression of  stent hypersensitivity ?

It is  often a coronary event in the acute phase and restenosis in chronic phase.

How much of acute stent thrombosis is related to stent allergy mediated reaction ?

The exact incidence  will  never be known. It could be high. Whenever a sudden unexpected early stent occlusion can be a suspect .

Is stent allergy a local reaction or systemic reaction ?

It is most often local .The drugs the stent elute can elicit a systemic reaction occasionally.

So what can be done to prevent this complication ?

Drug companies in it’s  package regularly  include the warning  message ! What does it imply to have a caution  on the covers ? .This warning simply represent about our ignorance in this issue. We presume it is a minor problem.

pci stent thrombosis stent allergy metal

Questions unanswered

  1. How does a cardiac patient knows whether he is hypersensitive to stainless steel or nickel ?
  2. Is it practical to have a stent allergic test in every patient before PCI ?
  3. Is routine administration of corticosteroids for few days after PCI an answer ?


R.Virmani , circulation 2004


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Answer: Do  coronary angiogram  for all patients  who had suffered from an acute myocardial infarction* ( Forget about all those mulitpage ACC/AHA  guidelines !).

For an  interventional cardiologist ,  it is often  considered a crime to  follow a conservative  approach !

*Caution This one line guideline is not based on scientific fact  but reality based . Ideally one should identify  high risk subsets among the patients who had an AMI .Patients who had complications during the MI get immediate CAG. Others need  a focused LV function asessment ,  pre discharge  sub maximal excercise stress test or perfusion studies .But this concept has been  virtually replaced by pre discharge coronary angiogram for all ,  in many  of the centres in the world.

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S. Venkatesan,  Madras Medical College. Chennai


If  a  major therapeutic procedure is adviced based on simply by experience or expert opinion  how can we say evidence based medicine is practiced !


                                    Evidence based cardiology  is  the  buzz word  in global cardiovascular  health care  organizations. All diagnostic  and therapeutic  interventions are  undergoing  rigorous randomized  trials  for  proof of  efficacy  and  safety. ACC/AHA   have published  management guidelines and it  has been accepted  as de-facto standard of clinical cardiology practice world wide.  In these guidelines  class  1  indication  is defined as Conditions for which there is evidence for and/or general agreement that the procedure is useful and effective. These indications are supported by three levels of evidence.(A,B,C) .It has been observed,   many of the recommendations  in  class 1  were supported by only level  C  evidence. (Expert consensus or  agreement  ). We  analysed how much of todays guidelines is  agreement based  and  how much is evidence based. The  latest  practice  guidelines  of  ACC/AHA   for  Acute myocardial infarction , Unstable Angina and Non–ST-Segment Elevation Myocardial Infarction , chronic  stable angina  ,coronary angiography  were analysed. The  no  of  class 1  indications  were counted  in each set of guidelines  and  each  of the indication were  sub grouped with reference to the  levels of  evidence  to which it was supported. There  were a total  of 210  class 1  indications.



Class  1

Level A

Class   1

Level  B

Class  1

Level  C

P value

1A vs 1C






UA  (66)




















 13.9%   of class 1  indications were based on  level  A evidence.  42.4%  of class 1 indication were based  on Level C  ( agreement  of experts).Though evidence based cardiology   is   considered  to  define  the  standards in  Cardiology  practice  in reality  we lack evidence in most of the situations. 

                                       We  conclude  that  consensus or  agreement  based cardiology  practice is the dominant theme in current   ACC/AHA 

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