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Posts Tagged ‘drug eluting stents’

Which is the “Numero uno”  cause  for  acute stent thrombosis  in real world  Cath labs ?

  1. Hypersensitivity  reaction  to metals
  2. Poor deployment of stent
  3. Inadequate  Anti-platelet  regimen
  4. Drug eluting stent

Answer :  2 .(Indisputably  correct )

It is estimated  at-least 4 out of 10 stents  we implant  is  sub-optimally  deployed .Only a fraction of them go for complication .Coronary endothelium silently  tolerates our  aggression .

How to  prevent this ?

  • Meticulous pre procedure analysis of lesion
  • Preparing the lesion if toughness is anticipated
  • Personal  mind application in stent size  selection
  • A slow , steady  non aggressive PCI
  • Liberal  pre and post dilatations
  • Judious use of IVUS and OCT ( Mind  you a  prolonged  IVUS procedure  can occasionally convert a good deployment into bad one !)
  • A  good quality anti-platelet regimen.

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Radiation injury to coronary artery  is rarely given a thought , in spite of   prolonged fluro-scopic time  during  many complex angioplasties.While the cardiologists are fully protected the patient’s heart takes on the brunt of the attack.

What happens to the coronary endothelium -metal interface when X -rays pass through it ?

It is well known the radiation delivered to a tissue is many times  amplified if a metal interface is present. Further , the metals can produce heat on exposure to radiation . This absorption and heat varies with different metals .

The radiation injury to coronary endothelium  could be  significantly higher with DES , as the polymer in it absorbs more radiation than the bare metal stent. This could be responsible for late complications of DES.

The above  concept (unproven though !) is  proposed  by  http://circ.ahajournals.org/cgi/content/full/104/5/e23 .In this study Gold coated coronary stents were found to be less safe than conventional stent

It may take many years to know the truths  about  radiation injury caused by  of coronary stents  .

But always remember , unproven concepts are  not synonymous with wrong concepts !

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The world of  medical science is  moving in a alarming speed.In any field , speed is always dangerous ! That’s why we have speed breakers , traffic police , speed cameras , etc etc . The medical world  is flooded with new devices, drugs , procedures . Though the mankind is benefited with many of them , a equal number could do the opposite.

How to identify which is causing benefit and which doing harm ?

It is a horrible fact , this is the most difficult exercise  for the  medical academia   . . . Still worse , harm will masquerade as benefit ! Further ,  beneficial concepts are  often buried alive if  it lacks  glamor  or  commercial value (Eg: The Digoxins,)

Lay public (as well as )  the physicians   are fed with half-baked ( Often quarter baked !) medical information .Many  of the medical journals,  guidelines , sponsored  seminars  ,  some times  even text books do a clandestine  campaign  . Even after a completion of major trial,  real truths rarely  come out . Funnily ,  they call them aptly , as blinded study ! Who is blinding whom is a different issue .

So ,  in  this  new millennium , thousands of innovations are on the pipeline. These pipes are often  infested with trivial , duplicate or even  harmful  concepts waiting for a grand release into human domain.

Take the story of coronary stents

In 1977 , Gruntzig mastered the  opening  of  the obstructed coronary  arteries with a simple balloon without any add ons . That patient is still alive  without  angina  . In the next 30 years we have ridiculed (Rather , we were compelled  to ridicule it ! * Read the related article  Is  there a role for  plain balloon angioplasty ?

Technology made  it  possible to introduce a  gamut of intra coronary  devices .We used (?abused ) all sort of anticancer drugs within the tender human coronary arteries .In 2002 , we claimed to  have climbed the summit and conquered  the restenosis with DES. And in 2010 , every one knows  what is happening to DES .

The malaise is  deep rooted  in every specialty . Next  came the  Stem cell fiasco ? and more  recently huge  conflicts of interest exposed  in the  vaccines  against H1NI

Final message

Who is going to regulate the menace ?  Hmm . . . . then  . . . Who will regulate the regulators ?

Is there a way out for our patients ?  or  they  have to suffer with it  along with the disease . The later is  more realistic option !

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Drug eluting stents are liberally used  worldover .

It is very unfortunate ,while the jury is still confused about the role of DES  “even”  in chronic coronary syndrome ,

There has been widespread use of DES in  the   potentially hazardous    thrombotic milieu  of STEMI  . It is well known  the DES ( polymer and drug)   has a dangerous liaison  with the thrombus.

Even as the evidence base was about to accumulate against the DES in STEMI , there was  an undue haste in the use of  this stent in STEMI .

Now in 2010 the results are out the DEDICATION trial

  • The culprit is out
  • The truth exposed
  • DES kills more life than bare metal stents   during primary PCI

Read this article  ,just released in Atlanta 2010

http://www.cardiosource.com/clinicaltrials/trial.asp?trialID=1618

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Drug eluting stents have  taken the cardiology community by storm . Millions of drug eluting stents are implanted every year. Sudden stent occlusion without  any warning has been the major threat of DES. Dependence of these patients , on meticulous dual anitplatelet  therapy is another  important caveat .This  issue  gets further complicated as we recognise “ clopidogrel  resistance” in many of this population . This , in effect  pushes these DES  patients  back into higher risk category.

So the cardiology community   cannot afford to  shy  away from answering  the following  vital questions !

How safe is DES  in the long run ? Are we really convinced ?  Is it acceptable to leave a DES patient’s life at the mercy of clopidogrel  which has it’s own idiosyncratic behavior ?



While this debate is getting hot , this new year(  2010) ,  there is  further bad news for DES .

Read this article from  European heart journal 2010

http://eurheartj.oxfordjournals.org/cgi/content/abstract/ehn553

A new complication  termed  ” Late stent malapposition” has been found  to occur  more frequently  in DES  than in other stents !

Stent malapposition could be technical in many , but when it  occurs late , it is  clearly  something to do with stent content  or it’s behavior with the vessel wall .

Some consider it as a partial  late  stent rejection due to late hypersensitivity reaction to the drug and the polymer .

Read a related blog : And now  drug abuse inside the  human  coronary artery

Final message

Drug eluting stents, ( Which  I think ,   has been  released  prematurely  into the  human domain !)  will face a strict scrutiny in the coming years and a turbulent time is expected.

Future perfect ? All the following statements can be true in isolation !

  • Even , plain balloon angioplasty (POBA) can be appropriate or  preferred over stents in many lesions.
  • Bare metal  stents are often better than DES .
  • Biodegradable  stents could prove  better than DES
  • And finally , medical management  ( if  effective and feasible  )  could be better than best stent

Reference

http://www.invasivecardiology.com/articles/Late-Acquired-Stent-Malapposition-after-Sirolimus-Eluting-Stent-Implantation-Full-title-bel

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Coronary stents have revolutionised the management of CAD. Stents are metallic scaffolding devices that help keep the atherosclerotic plaque  plastered within the coronary arterial wall.Thus it gained the name angioplasty. Stents have aradial strength that  exerts a constant force on  the plaque . Since metals are unfriendly partners for coronary artery , we need to have minimum metal within the coronary artery.The stent struts weave around the lumen generally the stento/ artery area ratio should be as less as possible (15%).

But this has a trade off .The uncovered area of plaque tend to project into the lumen .This is many times not significant.But can be a problem if the plaque is very soft and bulk of the lipid core may reenter the lumen.this event is called plaque prolapse.

plaque-prolapse

What is the time taken for plaque to prolapse ?

Generally it is late event.But it can happen immediately after the procedure also.

Which type of lesions are more likely to have plaque prolapse ?

Eccentric and complex lesions especially with overhanging edges are prone for prolapse

What is the sequale ?

It can be benign.If there is a erosion due to stent struts can precipitate an ACS.It progresses into instent restnosis in many.

What is the angiographic appearnce ?

Angiographically it often appears as luminal  irregularity withi stented segment .

Many times , it may appear as a filling defect also.

Is there any specific issues in plaque prolapse in drug eluting stents ?

Coornary artery is not drugged uniformly by the drug eluting stents.In fact contact  lines of metalic struts  , through it’s micropore oozes the drug with polymer.Pathological studies have revelaed non homogenous drug penetration and resultant irregularity on the plaque surface.This could amplify the plaque penetration preferentially in few areas.

How to manage plaque prolapse ?

It should be managed as any other instent restenosis.Plaque resection with atherectomy devices has not solved the problem to the desired levels.A second stent is the most common approach advocated by the cardiologists.(Whic is not ideal though !)

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Drug eluting stents : A slap on the face of Evidence based cardiology . . .

Click the BMJ link or read below

 

venkat-bmj

It is often said science is sacred and unfortunately we forget ,  science is not a heavenly creation and it is the creation of scientist of varying grades of integrity fueled by the vested interest of medical industry . It has been a almost a daily affair , some of the devices and drugs are recalled or found to be unsafe on patients.

Now the big cat has come out .The Drug eluting stent has fallen from Hero to Zero in a short span of 5 years. It was projected to have zero percent restenosis in 2002 . And now we realize it is Zero percent truth.

What has started as anecdotal reports of late stent thrombosis has indeed become an epidemic in all DES patients. The five studies that has been published in the NEJM this month (March 2007) has convincingly proved how unsafe these stents are in most of the coronary population .

Millions of patients in whom this stent was implanted will carry an impending stent thrombosis and possibly an SCD . Who is to take care of them ?

The DES story is a clear cut case of getting premature approval for a dangerous form of treatment inside human coronary arteries.

It is amazing how the scientist’s eyes are shut by the illusion of knowledge and lure of wealth. How foolish they were to think drug which was administered via the stent will selectively prevent vascularisation and leave the normal endothelium intact . Now they realized , one should not suppress the endothelial growth around the stent and got the fundamental point wrong. Which was the key reason for the astonishing episodes of late stent thrombosis. When we play with biology of nature we have to be little more careful .God has created man and his heart for over a million years . One can not alter it by a 6 month follow up study of DES .

When ICDs were exposed last year , of similar disastrous outcome they were recalled and explanted . How are we going to unstent the millions of coronary arteries ?

Somewhere along the line the medical professionals have lost the battle against the Wall street and NASDAQ . Or how else we can explain repetition of similar events.

The wages for the modern technology , the patients have to pay a heavy price.

Let us all hope common man with common sense will reign supreme over the sixth sense of the uncommon man . . .

“Ignorance is better than illusion of knowledge”

Dr Venkatesan Sangareddi MD , Assistant Professor of cardiology , Madras medical college Chennai, India

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