Why PCI in left main CAD is considered an inferior modality than CABG ?
CABG is superior to PCI for the simple reason it provides complete revascularisation virtually in all patients with LMCAD , while PCI is possible only in a fraction of patients with LMCAD.
If we take 100 patients with left main disease may be ten (At best !) would be suitable for PCI ! In other words PCI is contraindicated in vast majority of LMCAD by technical criteria alone , while there can never be a contraindication for CABG in patients with LMCAD.(Except when , comorbidity precludes surgery )
Why PCI in LMCAD difficult ?
It is dependent on technicalities
CABG does not tackle a lesion, it simply avoids it and by passes it ” No great brains required”
while PCI takes on the plaque frontally , in the dangerous terrain of left main artery itself !
so, much caution, planing , logistics are required . Further , if there is a complication there is a potential
for catastrophe as the only supply line is cut off . This is the reason , cardiologists were worried to try this on
unprotected left main. (Protected LMCAD refers to left main disease following CABG wherein atleast LAD or LCX is grafted )
Points to ponder in LMCAD
- PCI is suited for isolated discrete LM disease.In realty this is seen in less than 5-8 % CAD.
- LMCAD is very often associated with critical and multivessel distal CAD . So these patients will be candidates for CABG.
- Left main ostium or LAD ostial involvement makes PCI a tougher exercise
- Calcification is more common in LMCAD that again makes PCI difficult.
The following article in Feb 2009 is a major blow for proponents of PCI for left main
http://circ.ahajournals.org/cgi/content/extract/119/7/1013
Final message
- Conquering left main disease is an interventionist’s ultimate dream.
- But, before that they have to tackle the bifurcation lesions .This is of vital importance, because 2/3 rd of left main patients have some form of bifurcation lesions. Current techniques , hardware and outcomes are far below the idealistic solutions in bifurcation lesions.
- Till that time , CABG would remain the only choice for all , but for a small fraction of isolated left main disease where PCI may be possible.
Dr.S.Venkatesan MD 