title: Elevated CK-MB with a normal troponin does not predict 30-day adverse cardiac events in emergency department chest pain observation unit patients.
abstract: BACKGROUND
  Prior studies indicate that an elevated creatinine kinase (CK)-MB imparts poor prognosis in patients with acute coronary syndrome despite a normal troponin. Its prognosis in the undifferentiated chest pain observation unit (CPU) population remains undefined.
  
  
  OBJECTIVE
  To compare rates and predictors of 30-day adverse cardiac events in 2 cohorts (CK ±/MB+ vs. normal [CK ±/MB-]) in low-moderate-risk CPU patients.
  
  
  METHODS
  Consecutive CPU patients were followed in a retrospective cohort study for primary outcome (acute coronary syndrome, percutaneous transluminal coronary angioplasty, coronary artery bypass graft, abnormal stress test, cardiac hospitalization, or death within 30 days) by using standardized chart reviews and national death registry. Exclusions were: those aged 30 years or younger, positive troponin, ischemic electrocardiogram, hemodynamic instability, heart failure, or dialysis.
  
  
  RESULTS
  Between January 2006 and April 2009, 2979 patients were eligible, of which 350 excluded and 2629 analyzed. MB+ compared with normal patients were more likely to be: older (mean, 53.4 ± 14 vs. 51.5 ± 12 years; P = 0.04); male (71% vs. 40%; P = 0.01); renal insufficient (5% vs. 2%; P = 0.01); hypertensive (50% vs. 44%; P = 0.04); dyslipidemic (44% vs. 33%; P = 0.01) obese (55% vs. 43%; P = 0.01); and with known coronary artery disease (14% vs. 5%; P < 0.01). Composite adverse events were 213 (8%) and did not significantly differ for either initial MB+ vs. normal (9.1%, 8.0%; odds ratio, 1.1, 0.7-1.9) or serial MB+ vs. normal (7.5%, 7.4%; odds ratio, 1.0, 0.5-1.8). In a multiple logistic regression model, male sex, diabetes, and prior CAD predicted adverse events, whereas CK-MB along with race, hypertension, smoking, dyslipidemia, family history, and obesity did not.
  
  
  CONCLUSIONS
  Elevated CK-MB does not add value to serial troponin testing in low-moderate-risk CPU patients.
authors: From the Departments of *Emergency Medicine and ‡Internal Medicine, Section of Cardiovascular Medicine, Yale University School of Medicine, New Haven, CT; †Department of Emergency Medicine, Baylor School of Medicine, Houston, TX; §Brown University School of Medicine, Providence, RI; and ¶Yale Center for Analytical Sciences, New Haven, CT.
authors: Basmah
authors: B
authors: Safdar
authors: Sarah K
authors: SK
authors: Bezek
authors: Albert J
authors: AJ
authors: Sinusas
authors: Raymond R
authors: RR
authors: Russell
authors: Matthew R
authors: MR
authors: Klein
authors: James D
authors: JD
authors: Dziura
authors: Gail
authors: G
authors: D'Onofrio
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood* / Q000175:diagnosis; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood*; D002637:Chest Pain / Q000097:blood / Q000175:diagnosis*; D015331:Cohort Studies; D052279:Creatine Kinase, MB Form / Q000097:blood*; D004636:Emergency Service, Hospital; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D014336:Troponin / Q000097:blood*
chemical_list: D015415:Biomarkers; D014336:Troponin; D052279:Creatine Kinase, MB Form