title: Significance of anterior Q waves in left anterior fascicular block--a clinical and noninvasive assessment.
abstract: BACKGROUND
  Electrocardiographic (ECG) Q waves in V leads (V2 or V3) pose a diagnostic challenge in the presence of left anterior fascicular block (LAFB). Benign Q waves in the absence of coronary artery disease (CAD) primarily due to LAFB have been described. This study evaluates Q waves in the presence of LAFB.
  
  
  OBJECTIVE
  Anterior Q waves in the presence of LAFB may not be indicative of myocardial infarction (MI).
  
  
  METHODS
  From 1990 to 1997, ECGs of 236 male patients with LAFB were analyzes for presence of Q waves in the V leads. Records were reviewed for evidence of CAD. Of 236 patients with LAFB, 61 (26%) had Q waves in the V leads. In this group, 31 patients were available for further analysis.
  
  
  RESULTS
  Of the 31 patients with Q waves in the V leads who were available for further study, LAFB was present in 22 patients (71%) and LAFB plus right bundle-branch block (RBBB) were present in 9 (29%). Of 20 patients with Q waves due to MI, 13 (65%) had LAFB and 7 (35%) had LAFB plus RBBB. Of 11 patients with benign Q waves, 9 (82%) and 2 (18%) had LAFB and LAFB plus RBBB, respectively. Benign Q waves were noted in 5.3% (11/206) patients with LAFB. The mean duration of Q waves and Q-wave location limited to V2 and/or V3 are 0.029 s and 64% versus 0.053 s and 15% in benign versus pathologic Q waves, respectively.
  
  
  CONCLUSIONS
  Patients with LAFB in the absence of MI may have Q waves in the V leads that are approximately 0.02 s in duration and restricted to one or two leads. This anomaly may represent a variation of conduction in the initial 0.02 s QRS vector due to LAFB.
authors.affiliation: Cardiology Section, Bay Pines VA Medical Center, Florida 33744, USA.
authors.forename: Udipi R
authors.initials: UR
authors.lastname: Shettigar
authors.forename: Anu
authors.initials: A
authors.lastname: Pannuri
authors.forename: George H
authors.initials: GH
authors.lastname: Barbier
authors.forename: Doreen O
authors.initials: DO
authors.lastname: Appunn
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016279:Atrial Function, Left; D002037:Bundle-Branch Block / Q000175:diagnosis* / Q000503:physiopathology*; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005189:False Positive Reactions; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000503:physiopathology*