Registry on Left Main Coronary Artery Bifurcation Percutaneous Intervention

The slowly accruing evidence on the treatment of patients with left main coronary artery (LMCA) disease drove evolution in guidelines, that currently establish equivalent safety and efficacy for percutaneous coronary intervention (PCI) as compared to surgery, with a class of recommendation that is subjected to the extension and complexity of concomitant coronary artery disease, as assessed by the SYNTAX score. The severity of LMCA disease, although extremely relevant due to the extent of the supplied myocardium, is often difficult to assess with traditional angiography, due to lack of appropriate angiographic views, absence of a true "reference" segment, interaction with the intubating catheter. Intravascular techniques with either imaging or functional assessment have been variously tested, although with a disturbing rate of discordant results; moreover, they are frequently underused for a number of reasons, including the additional time needed to assess both left anterior descending (LAD) and left circumflex (LCx) arteries, technical challenges, costs and the small risk associated with maneuvering such devices. Fractional flow reserve (FFR) measured from the coronary angiogram (FFRangio) alone recently documented a high diagnostic accuracy compared with pressure-wire derived FFR. As for the anatomical localization, the majority of LMCA lesions occur at the bifurcation, where PCI results are less favourable. The distal LMCA differs from the other bifurcations in several characteristics: a) a notable mismatch between the LMCA and the left anterior descending (LAD) artery, hampering the selection of an adequately sized stent, b) the presence of a trifurcation, with a large ramus arising from LMCA in about 10% of cases, c) the presence of left or co-dominant circulation, with the LMCA supplying all or nearly all left ventricular myocardium in about 15% of cases. Therefore, although the European Bifurcation Club (EBC) recommends a provisional side branch approach in