Clinical Characteristics and In-Hospital Mortality According to Left Main and Non-Left Main Culprit Lesions　― Report From the Japan Acute Myocardial Infarction Registry (JAMIR) ―

Background: Acute coronary syndrome (ACS) due to an unprotected left main coronary artery (LMCA) lesion is a critical condition, but there are limited data available on in-hospital outcomes of percutaneous coronary intervention (PCI). Methods and Results: The Japan Acute Myocardial Infarction Registry is a nationwide, real-world database. The clinical data on 13,548 ACS patients hospitalized between January 2011 and December 2013 were retrospectively collected from 10 representative regional ACS registry groups. We compared the 404 patients (3.0%) with LMCA ACS with the remaining 13,144 patients with non-LMCA ACS. The LMCA group was characterized by older age, lower rate of ST-segment elevation myocardial infarction, and higher rate of advanced Killip class. In-hospital mortality was significantly higher in patients with LMCA ACS than in those with non-LMCA ACS (23.3% vs. 5.5%, respectively; P<0.001). Primary PCI for non-LMCA lesions was associated with lower in-hospital mortality (OR, 0.48; 95% CI: 0.34–0.66), but that for LMCA lesions was not (OR, 2.89; 95% CI: 1.13–7.40). Longer door-to-balloon time was associated with Killip class ≥2 and higher in-hospital mortality in the non-LMCA group but not in the LMCA group. Conclusions: Primary PCI in patients with LMCA ACS is still challenging; therefore, effective strategies are needed.