title: Left bundle branch block without concordant ST changes is rarely associated with acute coronary occlusion.
abstract: BACKGROUND
  The Sgarbossa score has been used to identify acute myocardial infarction on ECG in the presence of LBBB but has relied on elevated CK-MB for validation rather than angiographic evidence of vessel occlusion.
  
  
  METHODS
  We determined (a) the presence or absence of Sgarbossa criteria with concordant (S-con) or discordant (S-dis) ST changes, (b) the presence of acute coronary occlusion or likely recent occlusion on angiography and (c) the biochemical evidence of myocardial infarction (Troponin T >0.10 μg/L, Troponin I >1.0 μg/L) in patients field-triaged with suspected AMI and LBBB.
  
  
  RESULTS
  Between April 2004 and March 2009, 102 patients had field ECGs transmitted by paramedics for triage--8 with S-con, 26 with S-dis and 68 with LBBB alone. Acute coronary occlusion was present in 8/8 with S-con but none of the S-dis or LBBB alone patients, and in all 8 S-con patients reperfusion resulted in resolution of S-con changes. Likely culprit lesions with TIMI 3 flow were found in 3 S-dis patients but stenting did not result in resolution of S-dis. LBBB did not resolve in any patient. Troponin was elevated in 26 patients--11 with occlusion or likely culprit lesions, 15 with non-ischaemic causes.
  
  
  CONCLUSIONS
  In the absence of S-con, LBBB is not associated with acute coronary occlusion and should not be used as criteria for reperfusion therapy in myocardial infarction.
authors.affiliation: Department of Cardiology, Royal North Shore Hospital, Sydney, Australia.
authors.forename: Ross
authors.initials: R
authors.lastname: McMahon
authors.forename: Way
authors.initials: W
authors.lastname: Siow
authors.forename: Ravinay
authors.initials: R
authors.lastname: Bhindi
authors.forename: Soon Y
authors.initials: SY
authors.lastname: Soo Hoo
authors.forename: Gemma
authors.initials: G
authors.lastname: Figtree
authors.forename: Peter S
authors.initials: PS
authors.lastname: Hansen
authors.forename: Gregory I C
authors.initials: GI
authors.lastname: Nelson
authors.forename: Helge H
authors.initials: HH
authors.lastname: Rasmussen
authors.forename: Michael R
authors.initials: MR
authors.lastname: Ward
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D015331:Cohort Studies; D054059:Coronary Occlusion / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography