Improving the Diagnosis of Culprit Left Circumflex Occlusion With Acute Myocardial Infarction in Patients With a Nondiagnostic 12‐Lead ECG at Presentation: A Retrospective Cohort Study

BACKGROUND: Left circumflex culprit is often missed by the standard 12‐lead ECG. Extended lead systems (body surface potential map [BSPM]) should improve the diagnosis of culprit left circumflex stenosis with myocardial infarction. METHODS AND RESULTS: Retrospective analysis of a hospital research registry (August 2000–August 2010) comprising consecutive patients with (1) ischemic‐type chest pain at rest; (2) 12‐lead ECG and 80‐lead BSPM at first medical contact; and (3) cardiac troponin‐T 12 hours after symptom onset and/or creatine kinase MB fraction, were undertaken. Enrolled in the cohort were patients with culprit left circumflex stenosis (thrombolysis in myocardial infarction flow grade 0/1) at angiography. Acute myocardial infarction AMI was defined as cardiac troponin‐T ≥0.1 μg/L and/or creatine kinase MB fraction >2 upper limits of normal. Enrolled were 482 patients: 168 had exclusion criteria. Of the remaining 314 (age 64±11 years; 62% male), 254 (81%) had AMI: of these, 231 had BSPM STE—sensitivity 0.91, specificity 0.72, positive predictive value 0.93, negative predictive value 0.65, and c‐statistic 0.803 for AMI (P<0.001). Of those with BSPM STE and AMI (n=231), STE was most frequently detected in the posterior (n=111, 48%), lateral (n=53, 23%), inferior (n=39, 17%), and right ventricular (n=21, 9%) territories. CONCLUSIONS: Among patients with 12‐lead ECG non‐ST‐segment–elevation myocardial infarction and culprit left circumflex stenosis, initial BSPM identifies ST‐segment elevation beyond the territory of the 12‐lead ECG. Greater use of the BSPM may result in earlier identification of AMI, which may lead to more rapid reperfusion.