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How do you manage a left main disease with good exercise capacity ?

Posted Jan 11 2010 9:54am

The term  left main disease (LMD)  invariably  creates  a  near  panic  reaction in   many of the   contemporary cardiologists . It may be acceptable   in  a broader sense, but it need to be realised , there  is a significant group of patients  with  isolated  non critical  LMD . Many times , these patients can be managed effectively with  intensive medical management.

However , the  following rules may be applied in the management of non critical isolated LMD

  • In patients  who present with unstable angina  ,there is nothing called non critical LMD .Any degree of lesion (Even a 20%)  is significant .
  • Lesions with irregular margins, hanging eccentric  plaques are always critical irrespective of obstruction.
  • LMD involving LAD /LCX ostium need to be tackled as an  emergency .

What are the safe left main disease ?

  • Isolated tapering  left  main artery .
  • LMD  with <  50% lesion.
  • A left main patient who is pain-free on a tread mill > 10 METS
  • Left main with stable angina responding well to medical therapy
  • New onset left main disease in a patient with functional LIMA to LAD /LCX *

*This is sometimes called protected  LMD.  Protects what ? Protects the LAD ,   in case of  complication occurring during LM stenting . If the  function of  LIMA graft is good enough to  protect LAD , why should we attempt to open  the diseased LM in the first place ?  It is an unanswered question !

Why is it riskier  to  stent an  insignificant  LMD or stable  LMD ?

A  left main artery ,  engulfed with a  50%   stable plaque is less riskier to develop an  ACS than an  artificially  normalised  left main lumen with a stent. This is especially true for the  drug eluting stents which need life long  dual antiplatelet therapy as the drug which is supposed  to  prevent  the  restenosis ,  interferes  with  the normal endothelialisation over the stent .

In effect,   PCI   especially  with a DES for a hemodynamically insignificant lesion is fraught with a risk of converting a stable  lesion into  potentially vulnerable lesion !

Final message

A discerning  reader may ask , is it possible at all ? . . .to  have a   patient  with LMD  & enjoying  good exercise capacity ?

Yes , it  may be  rare , but not “non existent” .  Remember ,  one of   the common cause  for  rarity in medicine is ” non recognition of a  fact” or   otherwise  called ” Ignorance”

It is an irony , LMD is considered  by many as a  homogenous  entity ,  even as we  acknowledge  there is a  huge spectrum of lesions among left main disease . There is a distinct (although small !  )  subset of LMD * where medical treatment could be ideal and PCI  may even carry greater hazard.

*The most important caveat in assessing a LMD  lies  in the   50% criteria. Calipers  we use ( often visual )are never going to estimate the lesion correctly considering the importance of  Glagovian  phenomenon . As of now ,  we have no simple means to  measure the vulnerability of a left main plaque .Thermography, OCR/Raman spectroscopy/ RF intravascular ultrasound would probable redefine the indications for intervention in LMD.

Legal issue in LMD

Can we  defend in the  court of law, if a patient loses  his life,  who was adviced  medical management for LMD ?

Any thing can be defended in this funny world of  judiciary . A person who kills in broad day light,  hundreds of  innocent lives can argue  he has never seen a gun ! and he may even,  be  acquitted  for want of evidence  !

How can we   prove  with evidence , the  death in question  occurred  “only because ” he was  adviced medical management ?

No court on the earth can prove it !

So , an occasional life lost due to an unintentional  judgment  error can  easily be argued in favor of the noble profession . Scientific  guidelines are only recommendations .If a person with a  significant LMD  due to  a smooth stable plaque , who has  little  symptoms , carry on with his daily activities comfortably  , his  cardiologist has every right to advice him  medical management.  The doctor , can not be penalised , provided  , he has explained  to the patient ,  that  he is deviating from the official guideline only  for the benefit of   the patient’s  health and  he   has  fully understood the issue.

Read further , for  more controversy !

Land mark  randomised control trials (RCTs) are generally  done in specialised centres with high degree of expertise . They rarely represent the real world patients  seen in  the remote towns (or even  cities ) of the  developing countries  .We can not equate a PCI  done in an  angiographic core laboratory , say in Cleveland or Mayo clinic  ,  with that of  cath labs  ,  that  works  with par time staff and non dedicated cardiologists . So , in these situations  intensive medical therapy (which do not have a geographical variation in efficacy! ) would score over complex procedures .

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