Acute myocardial infarction due to left circumflex artery occlusion and significance of ST-segment elevation

Acute occlusion of the left circumflex (LC) artery can be difficult to diagnose. The aim of the present study was to assess the incidence of LC occlusion in patients with acute myocardial infarction (AMI) requiring percutaneous coronary intervention (PCI), the frequency of ST-segment versus non-ST-segment elevation presentation among them, and to correlate the electrocardiographic findings with the outcomes. The clinical characteristics and outcomes of consecutive patients from November 2001 through December 2007 with AMI within 7 days before PCI of a single acutely occluded culprit vessel were included in the present analysis. Of the 1,500 patients, the culprit lesion was located in the right coronary artery, left anterior descending artery, or LC artery in 44.7%, 35.8%, and 19.5% of patients, respectively. Of the 1,500 patients, 72% presented with ST-segment elevation AMI, but only 43% were patients with a LC lesion (n = 127). PCI was significantly less likely (80%, 83%, and 70% for right coronary, left anterior descending, and LC artery, respectively; p < 0.001) to be performed within 24 hours for LC occlusions than for occlusions in the other territories. Among those with a non-ST-segment elevation AMI, the highest post-PCI troponin levels were in patients with a LC artery occlusion (median 1.4, 1.3, and 2.5 ng/ml; p < 0.001). No significant difference was found in the in-hospital mortality (4.4%, 7.4%, and 6.5%; p = 0.66) or major adverse cardiovascular event (9.2%, 13.9%, and 11.6%; p = 0.53) rates for right, left anterior descending, and LC occlusions, respectively. In conclusion, our results have demonstrated that in clinical practice, the LC artery is the least frequent culprit vessel among patients treated invasively for AMI. Patients with LC occlusion are less likely to present with ST-segment elevation AMI and have emergency PCI. The study results suggest that detection of these patients has been suboptimal, highlighting the need to improve the diagnostic approach toward the detection of an acutely occluded LC artery.