Percutaneous coronary intervention to treat unprotected left main: Common (un-answered) challenges.

Percutaneous coronary intervention (PCI) with drug-eluting stent (DES) implantation is a widely adopted strategy to obtain myocardial revascularization in patients with unprotected left main (LM) disease. Although thoroughly investigated across scientific literature, LM PCI offers patient-specific technical options and poses many operative challenges that cannot be fully addressed by the pub-lished studies. Therefore, we have summarized and discussed in this review possible options related to PCI in LM patients. First, functional and imaging assessment for LM is still evolving and requires increased dedication to identify patients requiring revascularization and to enhance the results in the case of PCI performance. Second, specific coronary atherosclerosis patterns of LM involvement (like an isolated ostial disease of one of its bifurcation branches, extensive disease jeopardizing both branches, etc.) pose specific challenges for DES implantation so that careful selection of technical options (stepwise provisional single stent, upfront 2-stent strategy, when and how apply "kissing ballooning") is required. Third, despite improvement of techniques, PCI-related ischemia might not be tolerated by some patients with LM disease so mechanical circulatory support devices may come into play.