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Posts Tagged ‘des’

                                                    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

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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

 

Questions that need to be answered

  • What is the long term effects of drugging a coronary artery ?
  • Is no reflow or slow flow  more common after DES , because of the adverse drug reaction in the distal vascular bed ?
  • If a patient  with  DES  undergoes a CABG later what  would be  the impact of the  drug on the graft ? Will the functional vasodilatation   affected ?

Final message

                                  A drug , to get a legal clearance it has to undergo  hundreds of rigorous tests . Finally it is cleared for that  specific indication for which it is tested  .Just because a drug is cleared for one purpose ( Paclitaxel for malignancy ) it does not mean it is safe to use for any other  purpose for which it is deemed to be useful . Exactly the  opposite is happening   in the  the field of interventional cardiology . No body wondered to think what would be the effect of these drugs on the normal coronary endothelial cells and vasculature.Is it not a crime ,  without analysing this particular issue  , dozens of drug eluting stents have been released in the market . And now,  sounds of crying  foul is heard world wide !

Let us thank  , the so called negative forces in cardiology  for making this an  issue . In science ,  the watch dogs should bark  at  times of danger not wag the tail !

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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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Stents are mechanical  devices like  a  spring ,  used to  keep an artery open after a PTCA or PCI.

des-why4

                                Bare metal stents(BMS) were found to have restenois rate of about 25%.  So it was perceived a stent should have it’s own protective coat , so that it won’t get restenosed.For this the researchers thought  anti cancer drugs are ideal as they block cell proliferation and thus neovascualrisation and restenosis.Alas, they were found dismally wrong ,  after all , neointiaml proliferation is only a part of the problem of restenosis  and simple blocking of cell growth is insufficient . The issue doesn’t stop with that, the anti cancer drugs incorporated within the stent simply can not differentiate normal from abnormal cells and

DES effectively blocks the normal endothelisation over the stents and make this highly vulnerable for acute stent thrombosis .

This complication is unique to DES and can result in SCD.Further ,during the last 6 years of DES , we recognised the restenosis rate has increased form the much hyped O % to almost 15% and it’s still growing . These  complications  has made a huge question mark over the future of drug eluting stents !

des-coverage

The concept of DES may not die , but which drug it should elute should be answered ! This  again is  going to be a long battle. So it is currently   adviced,  based  on common sense ( With due respects to  those RCTs  funded by industry )

Whenever you encounter a block within the coronary artery* Ask the following  questions in sequence  ,

  • Whether we can leave it alone  with medical therapy  ,  if the answer is no , proceed  to the next step !
  • Is there a possibility for plain balloon angioplasty in a given vessel (POBA, Yes !  the concept is not dead yet !)
  • If you decide a stent is required , Will  the  bare metal  do the job ?
  • In multivessel CAD  , Did the issue of increased metal load on the  long term outcome was considered ?
  • If lesions appear complex,  should we  not strongly consider CABG as an option ?

However  if we  have the habit of  ask ing the following  question  you are likely to deviate from scientific approach  

Is it possible to put a stent  across  the block ?

Yes , will be the answer most of the time ,and the patient will invariably get one or more stents  and carry a life long  stent related problems.

*The rule does not apply in Acute coronary syndromes

Also read this letter  posted by the author published in  British medical journal

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There are numerous complex grading for bifurcation lesions available.

The one proposed by Medina is simple and most useful.

In this grading three segments

  • Proximal main vessel
  • Distal main vessel
  • Branch vessel

Are given a code 0, and 1 if  lesion is present or absent .

This grading gives simple and fast method to label a bifurcatiuon lesion and to asssess the response to PCI. The only issue here is the individual  lesions are not graded , for example branch vessel ostium just involved about 20 % is not addressed . Further TIMI flow in these vessels may also be incorporated

How medina grading can be used to assess effectiveness of

angioplasty  ?

A patient with 1.1.1  after the treatment should revert back to 0.0.0.  if converted into 0.0.(.5) may indicate a residual side branch lesion  .5 shall indicate 50% residual lesion, .3 , 30% etc

 

What is the best management strategy for bifurcation lesions?

The topic has been discussed extensively for over a decade in various forums.

Though the lesions and intervention techniques  appear complex the basic concept is simple.

Following is the 8 point algorithm

1. Assess the bifurcation lesion accurately.

2. Apply the general rule and ask the first question whether PCI is neccessary at all ? if decided for PCI

3. Stent the main vessel.Protect the side branch.  

4. Dilate the side branch with a balloon.(KIss or through the struts) 

5. Very rarely,  if the side vessel is more significant and large  stent it and balloon the main vessel.

6. Use drug eluting stents with caution .

7. Resist the temptation of using two stents unless the situation demands and is absolutely required.

8. Never attempt to do bifurcation angioplasty during ACS as apart of primary angioplasty.( Unless you’re extremely competent, even then aim of primary PCI is to salvage myocarium quickly , not to provide TIMI 3 flow in non IRA vessel.)

Dr.S.Venkatesan.Madras medical college.Chennai.

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