Percutaneous coronary intervention (PCI) to the left main coronary artery (LM) presents important technical challenges that are both lesion and site specific. Available technology has improved and so has our understanding of how to optimise short and long term outcome, but nevertheless intervention to this area demands special consideration. Critical analysis of the literature can only be performed in conjunction with clear awareness of the limitations of the studies. Factors include: paucity of randomised trials comparing stent with surgery for LM lesions; the heterogeneous nature of most reported patient populations, so that papers often include a mixture of lesion types (ostial, body or bifurcation) or high and low risk patients; a lack of consistency of PCI technique, so that many series report a mix of plain old balloon angioplasty (POBA)/stent/debulking or combinations of these. Interpretation of existing literature is therefore necessarily complex and imprecise. Furthermore, as is common in the realm of PCI, the speed of change of both equipment and technique make much of what is “established” potentially irrelevant to “state of the art” practice: the impact of drug eluting stents (DES), newer bifurcation techniques, and concomitant pharmacological treatment being obvious examples. Nevertheless, the most recent guidelines on revascularisation from both the European Society of Cardiology and American Heart Association/American College of Cardiology still recommend coronary artery bypass graft surgery (CABG) for the majority of patients with unprotected LM disease.^1,2 It is in this context that the available data on LM PCI must be reviewed.

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The initial angiographic success rates for contemporary (that is, using stents) series of LM PCI are universally high. In elective series, reported procedural success is consistently above 90% and in the majority is close to 100%, even in series including bifurcation disease.³ By contrast, patients presenting with acute coronary syndromes caused …