title: Unraveling the spectrum of left bundle branch block in acute myocardial infarction: insights from the Assessment of the Safety and Efficacy of a New Thrombolytic (ASSENT 2 and 3) trials.
abstract: BACKGROUND
  Left bundle branch block (LBBB) complicates the diagnosis of acute myocardial infarction (AMI). The Sgarbossa criteria were developed from GUSTO I to surmount this diagnostic challenge but have not been prospectively validated in a large population with presumed AMI. We evaluated their utility in the diagnosis and risk stratification of AMI patients in ASSENT 2 & 3.
  
  
  METHODS
  Baseline electrocardiograms (ECG) of LBBB patients were scored using Sgarbossa's criteria (0-10) by 2 readers blinded to the CK/CK-MB data and clinical outcomes; 267 (1.2%) patients had LBBB on their baseline ECG.
  
  
  RESULTS
  Among 253 LBBB patients with available peak CK/CK-MB data, 158 (62.5%) had peak CK/CK-MB levels > 2x ULN, thereby qualifying for the diagnosis of AMI. A Sgarbossa score of 3 was shown in 48.7% of LBBB patients with elevated CK/CK-MB versus in 12.6% of those without a CK/CK-MB rise (P < .001). Patients with higher Sgarbossa scores, ie, 3, had a higher mortality compared with those with a score < 3, (23.5% vs 7.7% at 30 days P < .001; and 33.7% vs 20.2% at 1 year, P < .001, respectively).
  
  
  CONCLUSIONS
  Our findings validate the utility of Sgarbossa criteria for diagnosing AMI in the setting of LBBB. These criteria provide a simple and practical diagnostic approach to risk stratify this diagnostically challenging high-risk group and optimize risk-benefit of acute therapy.
authors.affiliation: University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Hussam
authors.initials: H
authors.lastname: Al-Faleh
authors.forename: Yuling
authors.initials: Y
authors.lastname: Fu
authors.forename: Galen
authors.initials: G
authors.lastname: Wagner
authors.forename: Shaun
authors.initials: S
authors.lastname: Goodman
authors.forename: Elena
authors.initials: E
authors.lastname: Sgarbossa
authors.forename: Christopher
authors.initials: C
authors.lastname: Granger
authors.forename: Frans
authors.initials: F
authors.lastname: Van de Werf
authors.forename: Lars
authors.initials: L
authors.lastname: Wallentin
authors.forename: Paul W
authors.initials: PW
authors.lastname: Armstrong
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000150:complications*; D002986:Clinical Trials as Topic; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000175:diagnosis*; D011379:Prognosis; D018570:Risk Assessment