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 mu g/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.