Aikawa T, Yamaji K, Nagai T, et al. - Researchers intended to determine if there is an association between institutional and operator volume and in‐hospital outcomes in patients undergoing percutaneous coronary intervention (PCI) for unprotected left main coronary artery disease using generalized linear mixed‐effects model. Using data from the Japanese nationwide J‐PCI Registry (National PCI Data Registry) between January 2014 and December 2017, they analyzed characteristics and clinical outcomes of 24,320 patients undergoing PCI for unprotected left main coronary artery disease at 1,102 hospitals by 7,244 operators. Institutional PCI volume was correlated with better in‐hospital outcomes in patients undergoing PCI for unprotected left main coronary artery disease, rather than operator‐based.