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Learning objectives To understand the evolution in the strategies for the treatment of left main stem (LMS) disease in light of the three principal trials relating to this topic: SYNTAX, Nordic-Baltic-British Left Main Revascularisation (NOBLE) and Evaluation of Xience Versus CABG for Effectiveness of Left Main Revascularization (EXCEL).
To understand the similarities and differences in the SYNTAX, NOBLE and EXCEL trials.
To understand the relevant role of the Heart Team in the decision process for the best treatment strategy for LMS disease.
Introduction
Obstructive atheroma of the left main stem (LMS) is relatively unusual as it is present in only 4% of diagnostic coronary angiograms. 1 Historically, disease of the LMS has been treated with particular respect as the LMS provides blood supply to at least two-thirds of the left ventricle, 2 since prognosis after diagnosis of LMS obstruction is poor without treatment and because percutaneous coronary intervention (PCI) to the LMS usually involves a major bifurcation with higher calcific and fibrotic components than atherosclerosis elsewhere in the coronary tree. 3 4 These historical data and technical challenges resulted in coronary bypass grafting (CABG) being the standard treatment of LMS narrowing especially because of the excellent results achieved using the left internal mammary artery graft to the left anterior descending artery. 5
Encouraging outcomes when treating the LMS with PCI in patients unsuitable for surgery and technical advances in the predictability of PCI outcome have generated interest and reconsideration of the relative merits of PCI and CABG. Four small preliminary studies 6-9 were performed, but provocative data from the randomised Synergy between PCI with Taxus and Cardiac Surgery (SYNTAX) trial substudy 9 provided sufficient circumstantial evidence for the initiation of two international multicentre randomised comparative trials of surgery versus PCI for LMS disease: Evaluation of Xience Versus CABG for Effectiveness of Left Main Revascularization (EXCEL) 10 and Nordic-Baltic-British Left Main Revascularisation (NOBLE). 11 Both trials reported their primary endpoints in late 2016, and in this review we analyse current management of LMS disease and how this may change after the publication of these two landmark trials.
Management of significant left main stem disease before 2016
Identifying the optimal management for patients with LMS disease has many facets, but framing the clinical scenario requiring treatment is...