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.
A normally functioning circulatory system is vital for our survival . We have about 6000 ml of blood, circulating all over the body in an approximate time of 15-20 seconds.The pressure at which this blood moves across the body is called the blood pressure . Hypertension or simply , high blood pressure is an undesirable hemodynamic disturbance in human circulatory system.Systemic hypertension is the most common type of hypertension. The blood pressure is primarily dependent on the status of the blood vessel(vascular resistance) and cardiac contractility. This regulation is under many neural and hormonal factors.Further the blood pressure varies depending upon the blood vessel calibre, and the local milieu.There is a progressive drop in blood pressure from major arteries to the small arteries .The pressure drop is maximum across the arterioles to reach the venules .The venous circulation has the lowest pressure, it ends up at right atrium with a mean pressure of 0- 5mmhg.
Dr.S.Venkatesan MD 
