title: Value of ST-segment depression in lead V4R in predicting proximal against distal left circumflex artery occlusion in acute inferoposterior myocardial infarction.
abstract: BACKGROUND
  Lead V(4R) faces the right ventricular free wall; it also reflects ischemia in the posterolateral wall lying opposite and manifests as ST-segment depression.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the usefulness of V(4R) ST-segment depression in distinguishing proximal from distal left circumflex artery occlusion in acute inferoposterior wall myocardial infarction.
  
  
  METHODS
  We retrospectively analyzed 239 patients who had first acute inferoposterior myocardial infarction, were admitted within 6 h from onset of symptom, and had coronary angiography performed within 4 weeks. Patients who had bundle-branch block or concomitant significant stenoses in the proximal and distal segments of the same vessel or of both vessels were excluded. The electrocardiographic and angiographic findings were reviewed by two independent groups of investigators.
  
  
  RESULTS
  V(4R) ST-segment depression > or =1.0 mm was found in 8 of 46 patients (17.4%) with left circumflex artery occlusion but none (0%) with right coronary artery occlusion. Among the group with left circumflex artery occlusion, the mean magnitude of V(4R) ST-segment depression was greater in proximal than distal occlusion (0.82 +/- 0.65 vs. 0.03 +/- 0.12 mm, p < 0.0001). V(4R)ST-segment depression > or =1.0 mm was found in 8 of 14 patients (57.1%) with proximal occlusion but none (0%) in 32 patients with distal occlusion. The sensitivity and specificity to predict proximal occlusion were 57.1 and 100%, respectively.
  
  
  CONCLUSIONS
  V(4R) ST-segment depression > or =1.0 mm was not useful for differentiating left circumflex and right coronary artery occlusion because of its low sensitivity. It is a fairly sensitive and very specific sign of proximal left circumflex artery occlusion.
authors.affiliation: Cardiac Medical Unit, Grantham Hospital Hong Kong, 125 Wong Chuk Hang Road, Hong Kong. jimmanh2002@yahoo.com
authors.forename: Man-Hong
authors.initials: MH
authors.lastname: Jim
authors.forename: Hee-Hwa
authors.initials: HH
authors.lastname: Ho
authors.forename: Chung-Wah
authors.initials: CW
authors.lastname: Siu
authors.forename: Raymond
authors.initials: R
authors.lastname: Miu
authors.forename: Carmen Wing-Sze
authors.initials: CW
authors.lastname: Chan
authors.forename: Stephen Wai-Luen
authors.initials: SW
authors.lastname: Lee
authors.forename: Chu-Pak
authors.initials: CP
authors.lastname: Lau
mesh_terms: D000368:Aged; D017023:Coronary Angiography; D003327:Coronary Disease / Q000175:diagnosis* / Q000209:etiology; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology*; D011237:Predictive Value of Tests