Daly MJ, et al. - In this retrospective analysis, researchers investigated whether the diagnosis of culprit left circumflex stenosis with myocardial infarction was improved with the use of extended lead systems (body surface potential map [BSPM]). Using a hospital research registry (August 2000–August 2010), they identified patients with culprit left circumflex stenosis (thrombolysis in myocardial infarction flow grade 0/1) at angiography. Acute myocardial infarction (AMI) was present in 254 (81%) of 314 (age 64±11 years; 62% male) participants. For AMI, BSPM ST-segment elevation (STE)—sensitivity 0.91, specificity 0.72, positive predictive value 0.93, negative predictive value 0.65, and c-statistic 0.803 was detected among 231 participants. With initial BSPM in patients with 12-lead ECG non-ST-segment–elevation myocardial infarction and culprit left circumflex stenosis, the detection of ST-segment elevation beyond the territory of the 12-lead ECG was possible. AMI could be detected earlier with greater use of the BSPM, which could subsequently result in more rapid reperfusion.