title: Ability of myoglobin to predict mortality in patients admitted for exclusion of myocardial infarction.
abstract: BACKGROUND
  Myoglobin can be used as an early marker to diagnose myocardial infarction (MI); and although nonspecific for myocardial necrosis, it seems to be a strong mortality predictor. Because myoglobin elevations are often present in patients with renal insufficiency, it is possible that the predictive value of myoglobin is secondary to identifying patients with renal insufficiency.
  
  
  METHODS
  Consecutive patients admitted for MI exclusion without ST elevation on the initial electrocardiogram underwent serial assessment of cardiac markers (creatine kinase [CK], CK-myocardial band [MB], and troponin I [TnI]). Myoglobin was assessed at the time of admission and/or 3 hours later. Renal insufficiency was defined as a creatinine clearance <60 mL/min. Multivariate analysis was performed to identify predictors of 30-day and 1-year all-cause mortality.
  
  
  RESULTS
  A total of 3461 patients were included in the analysis. Overall 30-day and 1-year mortality was 2.4% and 9.7%. Myoglobin was elevated in 675 (20%), CK-MB in 421 (12%), and TnI in 517 (15%). Among the 993 patients with renal insufficiency, myoglobin was elevated in 43%, CK-MB in 17%, and TnI in 21%. Independent predictors of 30-day and 1-year mortality were similar and included age > or =65 years, prior MI, and an ischemic electrocardiogram, whereas myoglobin was the strongest multivariate predictor (odds ratio [OR] 2.8, 95% confidence interval [CI] 2.1-3.7), including those with renal insufficiency (OR 2.3, 95% CI 1.6-3.4). Troponin I had borderline predictive value (P = .08, OR 1.4, 95% CI 0.96-2.0), whereas CK-MB was not predictive in either group.
  
  
  CONCLUSIONS
  Despite the absence of cardiac specificity, an elevated myoglobin strongly predicts mortality, even in patients with renal insufficiency.
authors.affiliation: Cardiology Division, Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA 23298-0051, USA. mckontos@vcu.edu
authors.forename: Michael C
authors.initials: MC
authors.lastname: Kontos
authors.forename: Rajat
authors.initials: R
authors.lastname: Garg
authors.forename: F Philip
authors.initials: FP
authors.lastname: Anderson
authors.forename: Charlotte S
authors.initials: CS
authors.lastname: Roberts
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Ornato
authors.forename: James L
authors.initials: JL
authors.lastname: Tatum
authors.forename: Robert L
authors.initials: RL
authors.lastname: Jesse
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D052279:Creatine Kinase, MB Form / Q000097:blood; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis / Q000401:mortality*; D009211:Myoglobin / Q000097:blood*; D011379:Prognosis; D051437:Renal Insufficiency / Q000097:blood / Q000150:complications; D019210:Troponin I / Q000097:blood
chemical_list: D015415:Biomarkers; D009211:Myoglobin; D019210:Troponin I; D052279:Creatine Kinase, MB Form