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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