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 !
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 .