Percutaneous coronary intervention as an alternative to bypass surgery for unprotected LMCA stenosis

Hemodynamically significant left main coronary artery (LMCA) stenosis is found in approximately 4% of diagnostic coronary angiograms and is known as unprotected LMCA stenosis if the left coronary artery and left circumflex artery have no patent previous grafts. Previous randomized studies have demonstrated a significant reduction in mortality when revascularization by coronary artery bypass graft (CABG) surgery was undertaken compared with medical treatment. Therefore, current practice guidelines do not recommend percutaneous coronary intervention (PCI) for such a lesion, owing to the proven benefit of surgery and high rates of restenosis with the use of bare metal stents. However, with the advent of drug-eluting stents (DES), the long-term outcomes of PCI with DES to treat unprotected LMCA stenoses have been reported to be acceptable. Therefore, apart from the current guidelines, PCI for unprotected LMCA stenosis in many countries is often undertaken in individuals who are at very high risk of CABG or refuse to undergo a sternotomy. Future randomized studies comparing CABG versus PCI using DES for treatment of unprotected LMCA stenosis would be a great advance in the clinical knowledge of adopting appropriate treatments.