title: The delayed activation wave in non-ST-elevation myocardial infarction.
abstract: BACKGROUND
  Little is known about the relationship between the electrocardiographic characteristics and the infarct related artery (IRA) in non-ST-elevation myocardial infarction (NSTEMI). We found a curious phenomenon in electrocardiograms of patients with acute occlusion of left circumflex artery in NSTEM: A notch or deflection was often present in the terminal QRS complex in leads II,III and aVF or I,aVL . The objective of this study was to determine whether the previously unreported ECG phenomenon that we have found in NSTEMI could identify the culprit artery in non-ST-elevation myocardial infarction.
  
  
  RESULTS
  Our study included 218 NSTEMI patients who presented to our institution and underwent coronary angiography within 24 hours of admission. For convenience, 'N' wave was defined as a notch or deflection in the terminal QRS complex of the surface ECG. The duration of QRS with N wave before PCI was more prolonged than the duration of QRS without N wave (121 ± 12 ms vs 106 ± 11 ms, P<0.01). In the LCX group, 66(77%) patients had N wave in leads II, III and aVF, whereas only 5(6%) patients in the LAD group and 9(18%) patients in the RCA group had such ECG feature (P<0.001). A greater proportion of patients in the LCX group also had N waves in leads I and aVL (P<0.001). N wave in leads II, III and aVF was associated with 77% sensitivity and 89% specificity, respectively. N wave in leads I and aVL was associated with 64% sensitivity and 96% specificity, respectively.
  
  
  CONCLUSIONS
  The abnormal waveform in terminal QRS complex in NSTEMI ,which is described above, is the delayed activation wave of left ventricular basal region which the left circumflex artery supplies. It is associated with a higher specificity and higher sensitivity for culprit LCX in non-ST-elevation myocardial infarction. The delayed activation wave is a new pattern of ischemia in ECG.
authors.affiliation: Department of Cardiology, Shengjing Hospital of China Medical University, Shenyang 110004, China. niuts@sj-hospital.org
authors.forename: Tiesheng
authors.initials: T
authors.lastname: Niu
authors.forename: Peng
authors.initials: P
authors.lastname: Fu
authors.forename: Chenhong
authors.initials: C
authors.lastname: Jia
authors.forename: Yaling
authors.initials: Y
authors.lastname: Dong
authors.forename: Chunyu
authors.initials: C
authors.lastname: Liang
authors.forename: Qian
authors.initials: Q
authors.lastname: Cao
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Yang
authors.forename: Rao
authors.initials: R
authors.lastname: Fu
authors.forename: Xingang
authors.initials: X
authors.lastname: Zhang
authors.forename: Zhaoqing
authors.initials: Z
authors.lastname: Sun
mesh_terms: D000368:Aged; D017023:Coronary Angiography; D054059:Coronary Occlusion / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D003331:Coronary Vessels / Q000473:pathology*; D004562:Electrocardiography / Q000592:standards*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000473:pathology*; D012680:Sensitivity and Specificity