Acute Left Circumflex Coronary Artery Occlusion　― Diagnostic Problems of Initial Electrocardiographic Changes ―

Background: Acute coronary syndrome (ACS) with occlusion of the left circumflex coronary artery (LCX) poses diagnostic problems that may lead to a delay in reperfusion. Methods and Results: From a group of 1,269 consecutive patients with ACS, 138 patients with ACS due to LCX occlusion were analyzed for clinical, electrocardiographic, and angiographic presentations, as well as door-to-balloon (DTB) time. Electrocardiographic changes were classified into 4 patterns: ST-segment elevation in inferior/lateral leads (ST-E); ST-segment depression in V1–V4 (ST-D); no significant ST changes (No-ST); and others. The No-ST group was associated with a longer DTB time (P<0.0001) compared with the ST-E and ST-D groups. Compared with the No-ST and ST-E groups, the ST-D group presented with a more advanced Killip class (P=0.003), greater peak creatine phosphokinase (P=0.007) and peak creatine kinase-MB (P=0.006), more frequent proximal LCX occlusion (P=0.007), and worse 1-year outcomes (P=0.0034). Conclusions: One-third of ACS patients with LCX occlusion showed no ST-segment changes, resulting in significantly longer DTB time. Improving diagnostic accuracy is challenging but critical to avoid delayed reperfusion in these patients without electrocardiographic changes.