Outcomes of primary percutaneous coronary intervention in acute myocardial infarction due to unprotected left main thrombosis: The Asia‐Pacific Left Main ST‐Elevation Registry (ASTER)

INTRODUCTION: Prior studies of ULM STEMI have been confined to small cohorts. Recent registry data with larger patient cohorts have shown contrasting results. We aim to study the outcomes of patients with unprotected left main (ULM) ST-elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI). METHODS: The Asia-pacific left main ST-Elevation Registry (ASTER) is a multicenter retrospective registry involving 4 sites in Singapore, South Korea, and the United States. The registry included patients presenting with STEMI due to an ULM coronary artery culprit lesion who underwent emergency PCI. The primary outcome was in-hospital mortality. Secondary outcomes included major adverse cardiovascular events. RESULTS: A total of 67 patients (mean age 64.2 ± 12.8 years, 53 [79.1%] males) were included. The distal left main bifurcation was most commonly involved (85%, n = 57). Fifty one (76%) patients had TIMI 3 flow post-PCI. The in-hospital mortality rate was 47.8% (n = 32); 61% (n = 41) had cardiac failure, 4% (n = 3) had emergency coronary artery bypass grafting, 1% (n = 1) had a re-infarction, 3% (n = 2) had stroke and 55% (n = 37) had malignant ventricular arrhythmias. On multivariate analysis, predictors of in-hospital mortality included older age (odds ratio (OR) 1.085 (95% confidence interval (CI) 1.002-1.175), P = 0.044), diabetes mellitus (OR 10.882 (95%CI 11.074-110.287), P = 0.043) and absence of post-PCI TIMI 3 flow (OR 71.429 (95%CI 2.985-1000), P = 0.008). CONCLUSIONS: STEMI from culprit unprotected left main coronary artery stenosis is associated with significant mortality and morbidity. Emergency PCI provides an important treatment option in this high-risk group, but in-hospital mortality remains high.